Nat Hazards
DOI 10.1007/s11069-010-9539-0
ORIGINAL PAPER
Natural and man-made hazards in the Cayman Islands
D. A. Novelo-Casanova • Gerardo Suárez
Received: 4 November 2009 / Accepted: 7 April 2010
Springer Science+Business Media B.V. 2010
Abstract In this work, we analyze the various natural and man-made hazards that may
affect the Cayman Islands and determine the level of exposure of Grand Cayman to these
events. The magnitude, frequency, and probability of occurrence of the natural and manmade hazards that may potentially affect the islands are identified and ranked. The more
important natural hazard to which the Cayman Islands are exposed is clearly hurricanes. To
a lesser degree, the islands may be occasionally exposed to earthquakes and tsunamis.
Explosions or leaks of the Airport Texaco Fuel Depot and the fuel pipeline at Grand
Cayman are the most significant man-made hazards. The results of the hazard evaluation
indicate that there are four areas in Grand Cayman with various levels of exposure to
natural and man-made hazards: The North Sound, Little Sound, and Eastern West Bay
(Area 1) show a very high level of exposure; The Central Mangroves, Central Bodden
Town, Central George Town, and the West Bay (Area 2) have high level of exposure; The
Northwestern West Bay, Western Georgetown-Bodden Town, and East End-North Side
(Area 3) are under moderate levels of exposure. The remainder of the island shows low
exposure (Area 4).
Keywords Natural hazards Man-made hazards Vulnerability Grand Cayman Cayman Islands
1 Introduction
It is important to understand that disasters arising from hazards of natural origin are only
partially determined by the physical event itself. Reducing disaster risk requires the
assessment of the level of the hazard and the various types of vulnerabilities (economical,
social, environmental, etc.) of the affected society. When describing a hazard, it is
important to know the basic characteristics of hazardous events such as location, time,
D. A. Novelo-Casanova (&) G. Suárez
Instituto de Geofı́sica, Departamento de Sismologı́a, Universidad Nacional Autónoma de México,
04510 Mexico D.F., Mexico
e-mail: [email protected]
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intensity, and frequency (Smith 2001). Hazards are often grouped into three main categories, according to their causes: natural (earthquakes, hurricanes, etc.), technological
(explosions, release of toxic material, etc.), and anthropogenic (terrorist activity, crowd
related, etc.) (Schneiderbauer and Ehrlich 2006). However, hazards may have interrelated
causes, and the allocation of a hazard to one class is often difficult.
Thywissen (2006) states that every disaster starts with a hazard: known or unknown.
Independently of the origin of the hazard, they all have in common the potential to cause
the severe adverse effects that lie at the bottom of every emergency, disaster, and catastrophe. One important feature of a hazard is that it has the notion of probability or a
likelihood of occurrence. A hazard is a threat not the actual event. Any hazard can manifest
itself in an actual harmful event. In other words, if it can be measured in terms of real
damage or harm it is not longer a hazard but has become an event, disaster, or catastrophe.
Vulnerability is a function of the level of sensitivity or susceptibility of a system
(community, household, building, infrastructure, nation, etc.) to be damaged. Rashed and
Weeks (2003) pointed out that vulnerability is independent from any particular magnitude
of a specific natural event and depends only on the context in which it occurs. Thus,
vulnerability cannot be assessed in absolute terms. The performance of a determined
community should be assessed with reference to specific spatial and temporal scales.
Natural hazards are threatening events capable of producing damage to the physical and
social space where they take place not only at the moment of their occurrence, but on a
long-term basis due to their associated consequences. When these consequences have a
major impact on society and/or infrastructure, they become disasters (Alcantara-Ayala
2001). Hazards are the result of sudden changes in long-term behavior caused by minute
changes in the initial conditions (Scheidegger 1994).
In this work, we consider the following terms and concepts:
• Elements exposed: Elements such as people, buildings, and networks that are subject to
the impact of a specific hazard. Other elements that are also exposed include the
economy and the natural environment.
• Man-made hazard: A threat to a community having an element of human intent,
negligence, or error that involves a failure of a man-made system.
• Natural hazard: A specific natural phenomenon that may be capable of causing damage
to population or property characterized by a certain magnitude and likelihood of
occurrence. Common to all natural hazards is the uncertainty associated with the rate of
occurrence of a particular hazard, the magnitude, and the spatial extent of its impact.
• Vulnerability: We consider the definition provided by the Consultative Group for the
Reconstruction and Transformation of Central America (CGRTCA 1999) as part of an
analysis on the effects of Hurricane Mitch that occurred in 1998: ‘‘any condition of
susceptibility to external shocks that could threaten people’s lives and livelihoods,
natural resources, properties and infrastructure, economic productivity, and a region’s
prosperity’’. This description states that vulnerability is exacerbated in impoverished
areas due to weak infrastructure, a failure to implement prevention and preparedness
measures, and an inability to recover from a hazard event.
• Risk: The estimated impact that a hazard event would have on people, services,
facilities, structures, and assets in a community. It is defined by the following
expression (Crichton 1999):
Risk ¼ hazard elements exposed vulnerability
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ð1Þ
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Thus, ‘‘risk’’ is the probability of a loss, and this loss depends on three elements: hazard,
exposure, and vulnerability. If any of these three elements increases or decreases, then risk
increases or decreases, respectively’’ (Crichton 1999).
In order to analyze the hazards and the level of exposure of the Cayman Islands to
natural and man-made extreme events, we adapted a methodology similar to that developed by the North Carolina Department of Environment and Natural Resources and other
research partners during the study entitled ‘‘New Hanover County/Wilmington Project
Impact Partnership’’ (http://www.csc.noaa.gov/products/nchaz/htm/methov.htm 2001). In
another paper, we discuss the vulnerability of the critical facilities in the islands using the
same methodology.
Historical and recent data were collected and classified in order to identify and rank the
natural and man-made hazards. We identified four areas of high potential impact for the
main hazards in Grand Cayman and established a relative ranking of exposure to these
hazards in each of these areas. The different degrees of physical vulnerability for each
hazard are presented graphically with the aid of maps using a relative scoring system.
Spatial maps were generated showing the areas of different levels of exposure to multihazards. These maps are intended to be useful tools for emergency managers and policy
developers and to increase the overall awareness of decision-makers for disasters prevention and mitigation plans in the Cayman Islands. It is important to underline that this
study presents a first evaluation of the main natural and man-made hazards that may affect
the Cayman Islands. A full hazard analysis of the islands should include a complete and
quantitative hazards assessment modeling. However, our results constitute the basis of
future mitigation risk projects in the islands.
2 The Cayman Islands: geographic and geologic setting
Located in the western Caribbean Sea to the northwest of Jamaica, the Cayman Islands
(CI’s) are a British overseas territory comprised of three islands: Grand Cayman (GC),
Cayman Brac (CB), and Little Cayman (LC) (Fig. 1). These three islands occupy around
250 km2 of land area (Brunt and Davies 1994).
GC is approximately 35 km long and 13 km at the widest point wide. The highest
elevation is about 18 m above sea level, and the most striking geographical feature is the
North Sound, a shallow reef-protected lagoon with an area of about 56 km2. CB lies about
145 km northeast of GC. It is about 19 km long and a little over 1.6 km wide. LC is 8 km
west of CB and is 16 km long and 3 km at its widest point (Fig. 1). It is the flattest of the
three islands with its highest elevation being 12 m. To the west, an 11-km channel separates CB from LC (Brunt and Davies 1994).
The three islands are mostly flat and were formed by large coral heads, covering
submerged ice age peaks of western extensions of the Cuban Sierra Maestra range. The
highest point is The Bluff, a limestone outcrop 43 m in height on the eastern end of eastern
CB. The CI’s lowest elevation is the Caribbean Sea at sea level (Brunt and Davies 1994).
The Caymans are formed of two distinct formations of calcareous rock. The older limestone, called bluff limestone, was formed in the Oligocene–Miocene period, about
30 million years ago. This limestone forms the central core of each island. It is a dense
karstic limestone. Surrounding this bluff limestone core is a coastal limestone terrace
called ‘‘ironshore’’ which is a formation of consolidated coral, mollusk shells, and marl
with some limestone. It was formed about 120,000 years ago in the Pleistocene period
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20o N
19.4o N
WEST
BAY
LITTLE
SOUND
NORTH
SIDE
NORTH
SOUND
CENTRAL MANGROVES
GEORGE
TOWN
BODDEN
TOWN
EAST
END
19o N
SOUTH
SOUND
19.3o N
81.4o W
81.1o W
81o W
80o W
Fig. 1 The tectonic boundaries of the Caribbean Plate and the location of the Cayman Islands. The major
geologic faults in the northern Caribbean are shown. The Gonave plate is bounded by the Oriente fault to the
north that passes just south of the Cayman Islands, and the Walton fault to the south of it, passing through
Jamaica (after DeMets and Wiggins-Grandisson 2007)
(Folk et al. 1973). Due to the porous nature of the limestone rocks that are present along
with the absence of much relief of any kind, all of the Caymans lack rivers or streams (Folk
et al. 1973).
The Bluff Group is formed of the Brac Formation (Lower Oligocene), the Cayman
Formation (Middle-Upper Miocene), and the Pedro Castle Formation (Lower Pliocene).
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The Brac Formation, exposed only at the east end of Cayman Brac, is formed of limestones
and dolostones, whereas the overlying Cayman Formation is formed almost entirely of
finely crystalline dolostones. The uppermost Pedro Castle Formation is formed of limestones and dolostones. The original carbonate sediments, deposited on shallow banks in
water no more than 30-m deep, contained numerous corals, bivalves, gastropods, algae, and
foraminifera. Boundaries between these formations are unconformities that represent
periods of subaerial exposure and extensive karst development. The Brac Unconformity,
which separates the Brac Formation from the Cayman Formation, has at least 25 m of relief
on it. The Cayman Unconformity, which defines the upper boundary of the Cayman Formation, has at least 40 m of relief and many associated karst features. Diagenesis in the
Bluff Group has been extensive. Porosity is high with caves and fossil moldic porosity
dominating (Folk et al. 1973).
The Cayman Trough (CT) is a depression area on the seafloor of the Caribbean that
extends from the Belize margin to northern Jamaica (Fig. 1). At its deepest point, the CT is
over 7,500-m deep (Leroy et al. 2000). This margin consists of a 100–250 km wide
seismogenic zone of generally left-lateral, strike-slip deformation which covers over
2,000 km along the northern edge of the Caribbean Sea. This left-lateral strike-slip displacement is due to the eastward movement of the Caribbean plate relative to the adjacent
North American plate (Leroy et al. 2000). Geological and geophysical data from the region
suggest that the CT is underlain by oceanic crust accreted along a short north–south
spreading center located between the Oriente and Swan transform faults. Ultrasonic
seismic profiles of the CT revealed that the steep northern wall of the trench is virtually
sediment free (Rosencrantz and Mann 1991).
Based on plate reconstruction schemes estimates of the Caribbean-North America plate
motion rates, range from 1 to 2 cm/year (Rosencrantz and Mann 1991; De Mets et al. 1994).
Relative plate motion is taken up by strike-slip faulting along the northern boundary of the
Caribbean plate and ENE directed convergence along the eastern margin. A study by De
Mets et al. (2000) suggests that the motion between the Caribbean and the North America
plate is faster than predicted by the NUVEL-1A model averaging velocities of 1.8–2 cm/
year (Stein et al. 1988). Based on these results, we consider 2 cm/year as the average
velocity between the Caribbean and North American plates (Fig. 1). Recently, however, De
Mets and Wiggins-Grandison (2007) reported that the motion on the Oriente fault might be
as slow as 0.6 cm/year. The Oriente fault is the one immediately to the south of the CI’s. In
the interpretation of De Mets and Wiggins-Grandison (2007), a relatively small plate, called
the Gonave plate, lies between the Caribbean and the North American plate (Fig. 1).
The results of De Mets and Wiggins-Grandison (2007) suggest that most of the motion
between these two major tectonic plates is absorbed along the Walton fault, well to the
south of the CI’s (Fig. 1). They suggest that the Walton fault moves at an average rate of
1.3 cm/year. The deficit existing between the 2.0 cm/year of the Caribbean–North
American plate motion is apparently taken up by the Oriente Fault at a rate of approximately 0.6–1.1 cm/year. Thus, these authors argue that most of the motion of this plate
boundary has migrated to the southernmost Walton fault and little motion takes place today
on the Oriente Fault, immediately to the south of the CI’s.
3 Methodology
There are two primary components of the vulnerability assessment methodology used
here and developed by the North Caroline Department of Environment and Natural
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Resources (2001). The first is a tutorial, which defines a general process for conducting a
comprehensive community vulnerability assessment. The second component is the case
study in New Hanover County, North Caroline, USA, which illustrates the use of the
methodology in a specific community. This case study illustrates the use of geographic
information system (GIS) technology as a valuable resource for conducting hazards-related
analysis. A major feature of this product is a section focusing on the use of spatial data for
hazards planning. Several relevant GIS and remote sensing applications are introduced as
potential tools for supporting detailed hazards analysis.
The methodology was developed to assist communities in their efforts to reduce their
vulnerability to various hazards. It explains the process for analyzing physical, social,
economic, and environmental vulnerability at the community level. The foundation for this
tool was established by the findings of the H. John Heinz III Center for Science, Economic
and the Environment (1999). The methodology is a simple and straightforward approach
that lends itself to the quality and quantity of the available data (a full description of the
procedures can be found in: http://www.csc.noaa.gov/products/nchaz/htm/methov.htm).
Briefly, the steps involved in this methodology are as follows:
1.
2.
3.
4.
5.
6.
7.
Hazard Identification
Hazard Analysis
Critical Facility Analysis
Societal Analysis
Economic Analysis
Environmental Analysis
Mitigation Opportunity Analysis
Based on the goals of our study, which are to evaluate the level of exposure to natural
and man-made hazards of the CI’s, we considered only the first two steps. In Step 1,
hazards are identified by the systematization of all available information to determine the
main hazards that will be considered in the analysis. This can be either a comprehensive
list of hazards that pose some threat to the community or a more limited list of specific
hazards on which the community is interested. The hazards are characterized by its
probability of occurrence, size of area of impact, and the potential damage. For each
identified main hazard, we obtained a total score following Eq. 2 by assigning weights to
each factor depending on how critical that factor is:
Total score ¼ ðfrequency þ area of impactÞ potential damage magnitude
ð2Þ
The frequency, area of impact, and potential damage magnitude values are defined by a
scale of numbers ranging from 1 to 6, where: extremely low = 1 and very high = 6. The
ideal method for assigning score values to the various hazard threats would be a quantifiable probability assessment. Unfortunately, probability data are not consistent usually
among the different hazard types nor are they always available. As an alternative, this
methodology develops a relative priority matrix to use as a general guide for addressing the
different hazards. Designing such a matrix requires determining which factors are most
critical for a determined community and assigning weights accordingly. The purpose for
this step is to identify the hazards and their potential impacts. It is a subjective exercise
where the total scores alone do not have absolute statistical significance. The comparison
of scores, however, will provide relative rankings that guide the vulnerability assessment
process as well as the establishment of hazard mitigation priorities.
In Step 2, the exposure areas are determined for each hazard. The objective of this step
is to target priority areas for which a hazard evaluation is needed. The purpose is to identify
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geographically the areas that are most likely to be affected by a given hazard. Once the
areas exposed to the identified hazards are identified, a prioritization is developed using
local data sources. For each identified area, a relative level of exposure to the specific
hazard being addressed is established. These locations are considered as areas exposed to
different levels of hazard impacts. In many cases, it is possible to establish some relative
ranking within the exposure areas. For example, flood zones for 10- or 50-year floods
should be ranked higher than 100- or 500-year floods.
The different levels of exposure are then represented graphically using the relative
scoring system (higher scores for higher exposure areas). For example, hurricane storm
surge maps are usually created for five different categories of storms. Category 1 storms
are generally associated with the least severe winds and storm surge, while Category 5
storms are considered to be the most severe. In most cases, those areas subject to storm
surge in the lower category storms are also projected for inundation in all of the higher
categories. When developing a relative priority scoring system for storm surge inundation,
Category 1 storm surge areas would therefore have the highest risk of being flooded since
they are at risk of inundation in all storm events. The general concept is that locations with
no exposure to hazards will have a score of zero and each incremental increase in level of
exposure adds one point.
4 Data sources
The data for this study were collected via electronic means and from scientific sources in
the public domain. The Hazard Management Cayman Islands (HMCI) generously provided
part of this information. We interpreted and complemented our data with the use of the
following documentary sources (in alphabetical order):
• Cadastre Map of the Cayman Islands (Lands and Survey Department, Cayman Islands,
2007)
• Cayman Islands’ National Hurricane Plan 2006 (Emergency Operation Center, Cayman
Islands, 2006)
• Development Plan Map 2006 (Central Planning Authority, Cayman Islands, 2006)
• Map of flooding areas during Ivan Hurricane (Lands and Survey Department, Cayman
Islands, 2005)
• Map of Hurricane Ivan Preliminary Damage Assessment (Lands and Survey
Department, Cayman Islands, 2005)
• Map of location (latitude and longitude) of critical facilities (hospitals, schools,
shelters, fuel deposits, fuel and gas pipeline, government communications infrastructure, power stations, ports, water and sewage treatment plants, water storage plants,
airport, police and fire departments, critical government, and Red Cross installations)
(Hazard Management Cayman Islands, 2009)
• Petroleum Products Location Map (Lands and Survey Department, Cayman Islands,
2007)
• Preliminary Post-Ivan Environmental Impact Assessment Report (Department of
Environment, Cayman Islands, 2004)
• Series of Daily, Monthly, and Annual Precipitation of the Cayman Islands (Cayman
Islands National Meteorological Service, 2008)
• Terrain and Bathymetry Map, Grand Cayman, Cayman Islands (Lands and Survey
Department, Cayman Islands, 2007)
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• Topographic Map of the Cayman Islands (Lands and Survey Department, Cayman
Islands, 2007)
5 Hazard identification
5.1 Hurricanes
The year 2004 had an extraordinarily active hurricane season in the Caribbean basin.
Substantial damage was experienced with varying degrees of economic and social impact,
depending upon the resilience of the territories, their response capabilities and the size,
diversification and strength of their economies, societies and infrastructure (United Nations
Economic Commission for Latin American and the Caribbean, UN-ECLAC 2004). The
comprehensive assessments performed by the UN-ECLAC (2004) showed that in the CI’s
the impact, in terms of the annual GDP, was 138%.
During Hurricane Ivan, which impacted the CI’s on 12 September, 2004, GC experienced several storm surges that affected the North and South Sounds (Fig. 1; Young 2004).
Ivan also affected CB and LC with tropical storm winds. GC suffered the brunt of the storm
in all its intensity: windswept first from the southeast, in a northwesterly direction, and
with storm surges that flooded large portions of the coastal areas and deposited huge
amounts of sand over roads, houses, and infrastructure from East End to West Bay (Young
and Gibbs 2005). Ivan took the lives of two persons on GC, and it temporarily displaced a
significant part of the population. About 83% of the GC population was directly affected by
the wrath of this hurricane. The remaining 17% of the population was indirectly affected as
they sheltered or cared for those directly affected. The whole population experienced the
loss of electricity, water, and access to telecommunications for some period immediately
following the disaster. Entire Districts such as Bodden Town and the Eastern Districts
(Fig. 1) were isolated due to debris or road cuts, and individuals across the island were
isolated in their homes due to high water and debris (Young and Gibbs 2005).
Hurricane Ivan produced major damage to roads, utilities, and property, especially in
the western part of GC and along the southern coast (Young and Gibbs 2005). Although the
CI’s have a high level of insurance and hence, a great capacity for rebuilding, the islands
faced a shortage of immediate resources and had an important impact on the government’s
budget and cash flow. Cruise ships, for example, were able to return seven weeks after the
storm (Young and Gibbs 2005). Most public shelters performed extremely well during
Ivan, and almost 4,000 people safely rode out the storm.
Ivan was an unusually strong hurricane, which produced high winds, storm surge
flooding, heavy rain, and strong wave action. The impact on GC was short of catastrophic.
Young (2004) showed that the meteorological conditions were certainly capable of causing
a major catastrophe, it was only because of the high standards of the infrastructure,
especially shelter accommodation and other critical infrastructure, that loss of life and
injuries in the islands were kept to relatively low numbers.
Hurricane Ivan is by no means the first high-intensity hurricane that the CI’s ever faced.
In terms of casualties, the two deaths attributed to Ivan are dwarfed by the reported death
toll of 109 deaths during the 1932 hurricane (Craton 2003). The 1903 hurricane had an
estimated total of 15 men lost at sea, aboard vessels attempting to weather the storm.
A hurricane that occurred in 1785 claimed great loss of life due to the collapse of houses in
the strong winds, sailors lost at sea, and people drowning in a reported tidal wave. In 1876,
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Fig. 2 Tropical systems passing
within 96 km of Cayman Islands
since 1853. Tropical storms (TS):
blue; Category 1 hurricane
(HC1): green; Category 2
hurricane (HC2): yellow;
Category 3 hurricane (HC3):
orange; Category 4 hurricane
(HC4): red; Category 5 hurricane
(HC5): pink. Modified from UNECLAC (2004)
all churches and most houses were reported to have been totally destroyed, while those still
standing were severely damaged and barely habitable (Craton 2003). Fig. 2 shows the
paths of tropical storms and hurricanes that passed within 96 km of the CI’s since 1853
(UN-ECLAC 2004). The number of tropical systems passing near the CI’s at 5-year
intervals, from 1851 to 2006, is shown in Fig. 3. Most storms occurred from 1930 to 1934
Fig. 3 Number of tropical systems near Cayman Islands at five-year intervals for the period 1851–2006
reaching hurricane strength. Tropical storms: white; Categories 1–2 hurricane: gray; Categories 3–5
hurricanes: black (from Caribbean Hurricane Network: www.stormcarib.com)
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and the most severe hurricanes were registered between 1915 and 1919. On average, the
CI’s are affected, brushed or hit by hurricanes every 2.23 years. The average number of
years between direct hurricane hits (usually within 64 km to include small hurricanes) is
once every 9.06 years.
The months of September, October, and November are typically the most active for
hurricanes in the islands. During these months, storms tend to form in the southern
Caribbean and move north, into or close to CI’s. During the 55 years from 1950 to 2004,
GC experienced seven tropical storms and seven hurricanes, and CB and LC six tropical
storms and five hurricanes. The most important hurricanes that have directly impacted the
CI’s in recent years, in addition to Ivan, are:
•
•
•
•
•
Gilbert, September 1988
Mitch, October 1998
Michelle, November 2001
Wilma, October 2005
Dean, August 2007
5.2 Storm surge and storm winds
The greatest potential for loss of life related to a hurricane is from the storm surge. Storm
surge consists of unusual volumes of water that are pushed toward the shore by the force of
the winds swirling around the storm. This advancing surge combined with the normal tides
creates the hurricane storm tide, which can increase the mean water level to heights
impacting roads, homes, and the critical infrastructure. In addition, wind-driven waves are
superimposed on the storm tide. This rise in water level can cause severe flooding in
coastal areas, particularly when the storm surge coincides with the normal high tides.
Storm surges combined with wave action are responsible for much of the damage usually
caused by hurricanes, especially in large, low-lying coastal settlements. In addition to
causing flooding and damage to coastal structures, storm surge may also precipitate
flooding further inland through the blockage of the outfalls of drainage systems.
During Hurricane Ivan, storm surges in GC flooded large portions of the coastal areas
and deposited huge amounts of sand over roads, houses, and infrastructure from East to
West Bay. Onshore winds produced storm surges of 2–3 m and wave heights in excess of
8 m (Young 2004). According to information from the local meteorological office, by
10 pm local time on 11 September, 2004, the center of Ivan was located 182 km SE of GC.
At that time, hurricane winds with a force of over 161 km/h were already being experienced on the island (Young 2004). At 5 am, next day, the storm surge from the North
Sound (Fig. 1) was peaking at 3 m. The hurricane made its closest approach at 10 am when
the hurricane’s eye passed 34 km SW of the GC with winds of 241 km/h and gusts of
354 km/h. Another storm surge affected South Sound (Fig. 1) when the eye of the hurricane moved northeast. Ivan was a slow moving hurricane, which increased the exposure of
the island to hurricane force winds as well as increased the total amount of rain.
Key observations from the wind profile data during Hurricane Ivan (12 September,
2004) are (Young 2004; for locations see Fig. 1):
• Category 4 winds were sustained over the George Town area for almost 4 h, peaking at
225–233 km/h between 9 and 11 am local time.
• Category 4 winds were sustained in the West Bay area for around 3 h, peaking at 209–
217 km/h between 10 and 11 am local time.
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• Category 3 winds were sustained over the East End area for 4 h, peaking at
193–201 km/h at around 9 am local time.
• Using a standard conversion factor, wind gusts likely reached 289 km/h over George
Town.
• Tropical storm force winds (63–117 km/h) started in East End at around 1 pm local
time on 11 September and ended around 5 am local time on 13 September, a total
period of 40 h.
• Hurricane force winds ([ 117 km/h) were sustained somewhere in GC for almost 18 h.
Young (2004), using the NOAA best track hurricane database from 1851 and a simple
wind field model, estimated the peak winds during storms passing close to GC. His results,
with an error of 10–15%, demonstrate that Hurricane Ivan has been the most intense storm
in terms of wind speed on GC. The other two hurricanes with estimated winds of over
160 km/h were Gilbert in 1988 (172 km/h) and the 1903 storm (193 km/h). Other 21
storms were estimated with winds of 105 km/h or greater.
Both storm surge flooding and wave action were strongly influenced by the evolution of
Ivan’s wind-field as it passed GC. The geometry of North Sound caused the storm surge
flooding through the Red Bay-Prospect neck and across the western peninsula (Young
2004). The main storm surge-flooding peak was recorded along South Sound, likely the
result of winds having swung to onshore in that area. The continued onshore winds at
South Sound prevented draining of flood waters until the late afternoon; backflow into
North Sound occurred somewhat earlier than that, although southerly winds prevented
draining of water over Seven Mile Beach late into the evening. Severe wave damage
occurred only in a few places where onshore winds and no shallow reef protection came
together (Young and Gibbs 2005).
5.3 Floods
Climate in the Caribbean basin can be classified as dry-winter tropical with significant subregional variations in annual totals, length of the rainy season, and timing of rainfall maxima
(Rudloff 1981). Flooding in this region has been the cause of death and of much property
damage in hurricanes. Clearly, location is critical during floods. Low-lying lands, riverbanks, and lands adjacent to gullies should be avoided if possible; otherwise, appropriate
drainage measures must be taken. ‘‘Tropical Waves’’ drift through the Caribbean in the
summer months, often depositing large amounts of rainfall before they dissipate.
Atmospheric hazards, especially excessive rainfalls, are the most important cause of
floods. These vary from the semi-predictable seasonal rains over wide geographical areas,
which give rise to the annual floods in tropical areas, to almost random convectional storms
giving flash flood over some small basins (Smith 2001). Rainfall is seasonal in the CI’s.
The season spans from mid-May to November, with May to June and September to
October typically being the wettest months. Usually, the dry season takes place on February and March. Rainfall is generally the result of tropical thunderstorms, which develop
in the summer months, or localized rain resulting from the evaporation of water in the
central mangroves of the main island. Occasional surges of cooler air from continental
North America, the leading edge of which is called a cold front, are the main winter system
affecting the CI’s from late October through early April. These systems are the major
producers of rainfall during the dry-winter months although precipitation is not quite as
long lasting or of the same amounts as that brought by the summertime systems (Brunt and
Davies 1994).
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The average annual rainfall in the CI’s is about 11.4 cm being October the month with
higher rain precipitation, and the driest months are March and April (Fig. 4a). Localized
rainfall usually results when the summer heat causes evaporation of water in the central
mangrove wetlands and rain clouds are formed. These clouds generally drift to the west,
depositing rain on the western side of the island. The wettest day on record is January 18,
2003, with 21.5 cm of rainfall (Fig. 4b).
Other islands in the Caribbean with mountains register excessive rainfalls compared
with the CI’s. For example, the Blue Mountains of eastern Jamaica record around 560 cm
of rainfall per year, whereas Kingston, on the southeastern coast, receives about 400 cm.
Bridgetown, the capital of Barbados, has an average annual rainfall of 127 cm, while
Fig. 4 Average annual rainfall in different periods in Cayman Islands: a Average annual rainfall from
1957–2008; b Largest rainfall amount during a 24-hour period per year from 1971 to 2008 (Data from the
Cayman Islands National Meteorological Service, 2008)
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Bathsheba on the central east coast reports 254 cm. Recording stations in the Northern
Range in Trinidad measure some 302 cm of rainfall per year. Thus, in comparison, the
registered rates of rainfall may indicate that flooding from rainfall can be considered a
minor hazard to GC (Fig. 4a and 4b). However, if a tropical depression settles over the
island, it can rain for days with flooding causing severe problems. Normally, heavy rain
only takes place for a few hours, occasionally affecting some low-lying areas in the islands
with moderate flooding. This is due to the fact that the soil of the island is mostly formed
by limestone outcroppings with little soil (see Sect. 2). Two types of limestone form most
of the surface: (1) bluff limestone and iron shore and (2) limestone with coral, mollusk
shell, and marl (Alonso-Zarza and Jones 2007). Because limestone is very porous, rain is
quickly absorbed by the soil avoiding high flooding.
Weather-related hazards are usually directly modified by human activities in and around
urban areas (Klein et al. 2003). These human activities may include: (1) changing sediment
supply due to changing land use, hydrological modification, or coastal protection and the
consequent influence on erosion and deposition; (2) land claim of intertidal areas and
deepening of channels for navigation, which often increase extreme water levels and hence
flood risk; and (3) increased subsidence due to groundwater withdrawal, which often
reduces land elevation. Because of its geographic location, GC is exposed to many
weather-related hazards. For these reasons, it is important for the population of GC to
minimize or control this type of human activities to maintain flooding from rainfall as a
minor hazard. In general, urbanization also increases the magnitude and frequency of
floods (Smith 2001).
Based on our discussion above and because of the present relatively low rates of average
and daily rainfall (Fig. 4) and the soil conditions of the island, we consider flooding from
rainfall as a minor hazard to GC and will not be taken into account in our analysis.
5.4 Earthquakes
Although there are some reports of earthquakes felt strongly in the CI’s in the past, there is
no evidence in the historical record of a major destructive earthquake occurring very close
to these islands in the last 300 years. However, an event of magnitude 6.8 occurred on
December 14, 2004, approximately 32 km to the south of Georgetown, GC. The earthquake did not cause damage on the island. It provides, however, a stark reminder that the
CI’s lie along an active geological fault (Fig. 1). One may assume that the lack of strong
events in the past 300 years means that seismic energy has accumulated on the Oriente
fault and it may be released in the form of a large earthquake. Based on the available list of
historical earthquakes, we estimated that the maximum magnitude of an earthquake on the
Oriente fault might be between Mw7.2 and 7.5. This assessment of potential large earthquakes on the Oriente fault is made on the basis of the magnitude observed for the three
largest events that have taken place along this plate boundary in the past 100 years: the
Guatemala earthquake of February 4, 2006 (Mw7.5) that occurred on the westernmost
segment of this plate boundary; the Honduras earthquake of May 28, 2009 (Mw7.3); and
the Haitian earthquake of January 12, 2010 (Mw7.0).
Wells and Coppersmith (1994) have made a compilation of displacements observed on
geologic faults during many large earthquakes in the world. This compilation has led them
to estimate relations of the displacement observed on faults showing different types of
motion. Assuming that the earthquakes on the Oriente Fault would be of strike-slip type
and in the range of magnitude 7.2–7.5, the relations of Wells and Coppersmith (1994)
indicate that the expected motion on the fault during an earthquake would be 2–3 m.
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Nat Hazards
Using the average rate of motion of 0.6–1.1 cm/year reported by De Mets and WigginsGrandison (2007) for the Oriente fault, an approximate estimate of the recurrence rates
might be obtained. The calculation of the repeat times is done by dividing the maximum
displacement expected during an earthquake, which reflects the accumulated plate motion
over time, by the rate of motion observed on the fault. The upper bound is given by the
slowest rate of motion and the largest earthquake. Thus, if the maximum magnitude
expected is 7.5, the motion for an earthquake of this type is 3 m (Wells and Coppersmith
1994). Assuming the rate of motion on the fault is 0.6 cm/year, the resulting recurrence
rate is approximately 500 years. On the other hand, if the magnitude of the expected
earthquake was 7.2, the motion of the fault would be expected to be approximately 2 m.
Assuming the highest rate of motion (1.1 cm/year) in order to determine the lower bound
of the recurrence times, the resulting return period for these relatively smaller earthquakes
would be approximately 180 years. Thus, the return periods of earthquakes in the range of
magnitudes 7.2–7.5 in the Oriente fault would be approximately 180–500 years. These
figures, based on observed plate motion rates and expected maximum magnitudes, provide
a first-order estimate of the return periods of large earthquakes in the CI’s.
5.5 Tsunami
The main sources for tsunami in the Caribbean are earthquakes (generated at the boundaries of the Caribbean Plate or by intra-plate events). No evidence of tsunamis impacting
the CI’s exists since they were first permanently settled, 300 years ago. In the CI’s, due to
their geological characteristics, lack of rivers, and low topographic relief, there are no
sedimentary basins or large marginal deposits along the coast that may potentially slide if
they were to be made gravitationally unstable by the occurrence of a large earthquake or a
major storm, for example. Thus, local tsunamis originating from large landslides along the
coasts of the islands are highly unlikely. Potentially, the CI’s may be affected by tsunamis
generated in other parts of the Caribbean Sea and striking the coastlines of the islands. The
bathymetry of the islands, however, does not exhibit a continental shelf that shallows
gradually toward the coastline producing the amplification of tsunami waves, as it happens
on the continents. The CI’s coastline rises sharply from the ocean bottom, and this
bathymetry may not give rise to the rapid amplification of tsunami waves.
An analogy to the CI’s is the effect observed on Diego Garcia Island in the Indian
Ocean during the tsunami of December 26, 2004. Although the island was on the path of
the incoming tsunami waves, the island was essentially unaffected. Nonetheless, the coast
of Africa, several hundreds of kilometers downstream from Diego Garcia, suffered considerable damage due to the large tsunami wave generated along the coast. The reason for
this is that the island of Diego Garcia is a dormant volcano that rises sharply from the
ocean floor. The lack of a sloping continental shelf did not generate the large tsunami
waves observed on the continental shorelines.
Jones and Hunter (1992) identified large boulders that are as heavy as 10 tons along the
southern coast of GC. The boulders are derived from the Bluff Formation that forms the
rocky coastal terraces of present-day shore. The presence of sponge borings, encrusted
gastropods, and other marine flora and fauna indicates that the boulders must have been
submerged in seawater before being thrown inland. The authors dated with radiocarbon
techniques the coral of these boulders. This dating yields an age of 1,656 ± 32 years AD.
This age apparently reflects the time when these large boulders were removed from the
seafloor and thrust onshore over vertical distances of 18 m in some cases. The authors
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Nat Hazards
suggest that the most probable cause for the presence of these boulders is a local tsunami or
a major hurricane.
5.6 Landslides
As discussed above, the islands are generally flat lying with the highest point being 42 m.
Coastal cliffs are unlikely to exceed a few meters in this area of subdued topography. There
is not reported landslide activity not geological evidence for it in the CI’s. Occasional falls
of limestone blocks at low sea cliffs are possible, particularly in CB. Thus, landslides do
not represent a main hazard that is likely to have an economic or social impact in the
islands (McNally 1988; Richards 1975).
5.7 Volcanoes
Several of the islands of the Eastern Caribbean are volcanic in origin. However, there are
no active volcanoes on the CI’s. Also, the islands are far from the known active volcanoes
in the Caribbean area. The closest volcanoes are those in the Lesser Antilles and in Central
America. The long distance of the CI’s to active volcanoes indicates that volcanic hazard is
practically non-existent. Thus, we consider that no further evaluation is needed in this
respect.
5.8 Man-made hazards
Potential man-made hazards in the islands are (in alphabetical order):
•
•
•
•
•
•
•
•
•
Acid rain
Air pollution
Electronic threats
Environmental degradation
Fires
Infrastructure failure
Major airplane, cruise ships, medical and agricultural accidents
Mined and quarried land
Water pollution
There are no major industries or toxic chemicals in GC. Nonetheless, the fuel terminals
and fuel storage tank, as well as the fuel distribution pipeline, may constitute a potential
man-made hazard. The main fuel terminals and tanks as well as the fuel distribution line
could, under certain circumstances, exacerbate the impact of a hazard event by adding to
the danger. Fuel leaks may result through safety and relief valves, piping ruptures, fire,
equipment failures, overfills and overflows of storage tanks, and human error. In these
cases, the hazard posed by these facilities can be explosive, flammable, combustible, and
toxic, posing a potential risk to life, health, environment, or property that is located nearby.
Incidents with an involvement of structural or infrastructural system failures may consist of
technical, operational, or organizational failures.
Pipelines are transportation arteries carrying liquid and gaseous fuels. Pipelines are
buried and sometimes located above ground. Buried and exposed pipelines are vulnerable
to breaks and punctures caused by earth movement, material failure, operator error, construction defects, and tampering. If a pipeline fails during land movement, it can shear.
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Nat Hazards
When shearing takes place across abrasive materials or when the fuel comes in contact
with an ignition source, the sparks can cause the fuel to explode or burn.
6 Hazard analysis
From the results of the previous section, the following main hazards to CI’s are addressed
here:
•
•
•
•
Hurricane (flooding, storm surge)
Earthquake
Man-made hazard (fuel and gas terminals and fuel pipeline)
Tsunami
In the case of hurricanes, we consider flooding and storm surge as the main hazards for
the following reasons: (1) The two elements are the main causes of hurricane related
deaths; (2) Flooding from hurricanes can occur several miles from the coast impacting
communities and structures far inland; (3) Storm surges are responsible for much of the
damage usually caused by hurricanes, especially in large, low-lying coastal settlements;
(4) These two phenomena usually present themselves simultaneously.
Using Eq. 2, we developed a relative priority matrix as a general guide for addressing
the different hazards. The frequency, area of impact, and magnitude values of the potential
damage are defined by a scale of numbers ranging from 1 to 6:
Extremely low: 1
Very low: 2
Low: 3
Moderate: 4
High: 5
Very high: 6
Based on this scale, and considering the history of hazards in the CI’s and their past
impact discussed in the previous section, we assigned values of 6, 2, 2, and 1 for the
frequency of occurrence and of 6, 4, 1, and 2 for the area of impact due to hurricane,
earthquakes, man-made hazards, and tsunamis, respectively (Table 1). The values of 5, 4,
and 3 for the potential damage of hurricane, earthquake, and man-made hazards are also
justified from the history of past impacts. We assigned 2 to a tsunami’s potential damage
because most likely only the coastal zones of CI’s would be impacted.
It should be emphasized that the results indicated on Table 1 are indicative of the
relative level of hazard across CI’s. Although qualitatively defined, the higher the total
scores, the greater the relative degree of ranking of the hazard.
Table 1 Relative ranking
matrix of hazards at Cayman
Islands
a
(Frequency ? area
impact) 9 potential damage
magnitude
123
Hazard
Frequency
Area of
impact
Potential
damage
Total
scorea
Hurricane
6
6
5
60
Earthquake
2
4
4
24
Man-made
2
1
3
9
Tsunami
1
2
2
6
Nat Hazards
Following Step 2 of our methodology, to outline the exposure areas at GC, we considered the characteristics of each main natural hazard listed in Table 1. We targeted these
areas by establishing relative rankings among them. The varying degrees of exposure areas
are represented both through a relative scoring system (higher scores for areas exposed to
high impact hazards) and graphically in a map. For example, qualitative flood maps were
created for five different categories of storms. Storms of Category 1 are generally associated with the least severe winds and floods, while Category 5 storms are considered to be
the most severe. Generally, areas subject to floods in the lower category storms are also
projected for inundation in all of the higher categories. Thus, in our relative priority scoring
system for inundation, storm floods areas of Category 1 would, therefore, have the highest
probability of being flooded since they are exposed to inundation in all storm events.
Table 2 shows the relative priority scoring system developed for different areas at GC.
To facilitate our interpretation, the results are also presented in the corresponding maps
(Fig. 5a–5c). The general concept is that locations with no exposure to hazards will have a
score of 0 and each incremental increase in exposure adds one point:
Table 2 Level of hazards for
different areas at Grand Cayman
Hazard
Area
Score Highest Lowest
Categories 1 and 2
1
5
Category 3
2
4
Categories 4 and 5
3
3
4
2
Categories 1 and 2
1
5
Category 3
2
4
Categories 4 and 5
3
3
Remainder of Grand Cayman 4
Island
2
Hurricane
Flooding (Fig. 5a)
Remainder of Grand Cayman
Island
5
2
5
2
Storm surge (Fig. 5b)
Earthquake
Entire Grand Cayman Island
1–4
1
1
1
Very low
Near to
ocean
1
1
0
Remainder of Grand Cayman
Island
4
0
Fuel and gas tanks
Adjacent
areas
1
1
0
Fuel pipeline
Adjacent
areas
1
13
5
Tsunami (Fig. 5c)
Man-made hazard
Remainder of Grand Cayman
Island
Total
0
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Nat Hazards
a
b
c
Fig. 5 Flood a and Storm surge areas b for different hurricane categories. The arrow indicates the direction
of approach of the hurricane; c Tsunami hazard areas for tsunamis coming from the Caribbean Sea
No risk: 0
Very low: 1
Low: 2
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Nat Hazards
Moderate: 3
High: 4
Very high: 5
Notice that under our considerations, for the entire GC the score of 1 in Table 2 is given
only for earthquake hazard since, with the knowledge we have today, there is potential for
this hazard to occur evenly distributed throughout the country. Some variations may exist
due to varying soil conditions in GC. In some cases, soft or thick soils induce much higher
accelerations of the ground than would normally be observed on hard rock. The information available and the scope of this study do not allow a more detailed seismic zoning
based on soil quality.
7 Results and discussion
Flood zones resulting from hurricanes were delineated according to hurricane categories on
the Saffir-Simpson scale (Categories 1 through 5). The exposure scores for flood hazards
were determined by: (1) Using the flood distribution areas during hurricane Ivan as
determined by the Lands and Survey Department of Cayman Islands (2005) and
(2) Identifying areas with high potential for flooding by analyzing the characteristics of
the topography of GC from a Digital Elevation Model (DEM) and using a GIS.
The score of 5 was given to the area outlined in Fig. 6a considering that: (1) Zones
where coastal flooding and wave action are the highest during Categories 1 and 2 hurricanes are also likely to be inundated during stronger events as well and (2) On average,
Categories 1 and 2 hurricanes hit the CI’s every 2.23 years (Young 2004). The second
highest score of 4 was applied to Category 3 flood areas (Fig. 6b) because hurricanes of
this size usually hit the islands once every 9.06 years (Young 2004). A score of 3 is given
to hurricane Categories 4 and 5 (Fig. 6c) that take place approximately every 100 years
(Young 2004). Areas located outside the floodplain but appearing on flood-prone soils are
rated with a score of 2. However, as Young (2004) indicated, two 100-year hurricanes can
occur in successive years; the fact that Ivan occurred in 2004 does not give GC a guarantee
of 99 years without a similarly sized storm.
The results displayed in Fig. 6c are comparable to the results obtained from field
observations by the Lands and Survey Department (2005). This institution showed that up
to 70% of GC was submerged by seawater and/or rainwater for significant periods during
and after hurricane Ivan. However, around 20% of this flooding was less than 60 cm. Note
that in Fig. 6c, we are combining the results for hurricanes with Categories 4 and 5. If we
consider a hurricane with Category 4 (results not shown here), only about 70% of GC is
flooded as reported by the Lands and Survey Department (2005).
Locations that are subject to storm surges from the lowest category storm events are
considered the most exposed areas for this type of phenomenon. The identified storm surge
areas at GC were mapped from: (1) The storm surge areas during hurricane Ivan reported
by Young (2004) and (2) The characteristics of the topography of GC analyzed from a
DEM and using a GIS. These zones represent locations that might expect to be impacted by
storm surge during future hurricane events. Because of the difficulty in making clear
boundaries, a 0.25-mile buffer was established around the identified surge inundation
zones.
Categories 1 and 2 hurricane storm surge inundation areas are given a score of 5
(Fig. 7a). Category 3 inundation areas are given a score of 4 (Fig. 7b), and Categories 4
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a
b
c
Fig. 6 Areas showing their level of exposure due to flooding for hurricanes: a categories 1 and 2;
b category 3; and c categories 4 and 5. The arrow indicates the direction of approach of the hurricane
and 5 inundation areas are assigned a score of 3 (Fig. 7c) because it is considered that these
kinds of events take place approximately every 100 years at CI’s (Young 2004). The
results of Fig. 7c are in agreement with observations made by Young (2004). This author
points out that the geometry of the North Sound caused the storm flooding through the Red
Bay-Prospect neck and across the western peninsula during hurricane Ivan. According to
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Nat Hazards
a
b
c
Fig. 7 Areas showing their level of exposure due to storm surge for hurricanes: a categories 1 and 2;
b category 3; and c categories 4 and 5. The arrow indicates the direction of approach of the hurricane
Young (2004), the southern parts of North Sound (Fig. 1) were first extensively flooded as
a result of the early northeasterly winds. Then, as the winds swung around to the east, water
began to inundate the western shore of North Sound and, in places, pushed across the
western peninsula to Seven Mile Beach. At the peak of the storm, easterly winds over
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Nat Hazards
western GC and southeasterly over eastern GC caused storm surge inundation from both
the western side of North Sound and from South Sound simultaneously. The highest
flooding due to storm surges was recorded along South Sound (Fig. 1). This fact is very
likely the result of winds having swung onshore in that area. Similar flooding has occurred
on a number of occasions in the history of GC (Young 2004).
We consider that the seismic risk score is 1 throughout GC. This result is based on the
following considerations: (1) There is no evidence in the historical record of a major,
destructive earthquake occurring in the vicinity of the CI’s in the last 300 years and (2)
Taking into account our analysis of earthquakes presented in Sect. 5, the return period of
large earthquakes (magnitudes between 7.2 and 7.5) at CI’s is approximately in the range
of 180–500 years. These observations can be extrapolated to the CB and LC because
the geological fault where these large earthquakes may be generated lies parallel and to the
south of GC. Furthermore, there are no observations that would allow one to assess
the effect of local soil conditions in different parts of the islands. Deep and soft soils
usually normally produce larger accelerations and seismic intensities than those observed
at sites located on rock. Therefore, we consider that the three islands probably have the
same response to seismic waves.
As indicated in Fig. 5c, areas exposed to the impact for tsunamis were determined based
on distance from the coastline along the shore. Because of the low probability of the CI’s to
be impacted by a tsunami those areas inland of the coastline up to 0.2 miles are assigned a
score of 2 (low exposure). The remaining zones on the islands receive a rating of 1 (very
low exposure). As discussed above, we are considering that the CI’s may be affected by
tsunamis generated in other parts of the Caribbean Sea and striking the coastlines of the
islands. The bathymetry of the islands, however, does not exhibit a continental shelf that
shallows gradually toward the coastline producing the amplification of tsunami waves, as it
happens on the continents.
As pointed out before, the main fuel tanks, the Home Gas facilities, and the associated
pipelines constitute the main man-made hazards on GC. We assigned a score of 1 to zones
that may be impacted in the case of a major leak or an explosion. These areas are defined
as: (1) The circle centered on each of the five major storage tanks with 400 m radius and
(2) The area measured within 400 m distance from both sides of the distribution pipeline.
These zones of impact for man-made hazards at GC were based on studies of the affected
zones from explosions reported in similar circumstances (Arturson 1987; Sceptre Fundraising Team 2006).
Based on our previous discussion, GC can be divided basically into four areas with
different levels of exposure to natural and man-made hazards. These areas are (Fig. 8):
• Area 1: North Sound, Little Sound, and Eastern West Bay.
• Area 2: Central Mangroves, Central Bodden Town, Central George Town, and West
Bay.
• Area 3: Northwestern West Bay, Western Georgetown, Bodden Town, East End, and
the North Side.
• Area 4: Remainder of country.
Using a GIS, the relative individual scores for each area were added to create a total
score for that particular region (Table 3). From Table 2, we observe that the lowest and
highest potential risk scores are 5 and 13, respectively. These figures represent the maximum values for low and very high exposure zones. Under these conditions, our ranking to
establish the level of exposure for the four identified areas in GC is the following:
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Nat Hazards
Fig. 8 Areas showing the level of exposure to natural and man-made hazards at Grand Cayman resulting
from the analysis described in this paper
Table 3 Levels of exposure to natural hazards per area at Grand Cayman
Area
Hurricane
Earthquake Tsunami Manmade
Flooding Storm
hazard
surge
Total Level of
score exposure
Area 1: North Sound,
Little Sound, and Eastern
West Bay
5
5
1
0
0
11
Very High
Area 2: Central Mangroves,
Central Bodden Town, Central
George Town, and West Bay
4
4
1
1
0
10
High
Area 3: Northwestern West Bay, 3
Western Georgetown, Bodden
Town, and East End-North Side
2
1
1
1
8
Moderate
Area 4: Remainder of the island
1
1
1
0
5
Low
2
Low: 5–6
Moderate: 7–8
High: 9–10
Very high: C 11
Using these values, the qualitative level of exposure to natural hazards in the four
identified areas is established (Table 3, Fig. 8). The most exposed areas to natural and
man-made hazards at GC are the North Sound, Little Sound, Eastern West Bay, the Central
Mangroves, Central Bodden Town, Central George Town, and the West Bay regions. The
Northwestern West Bay, Western Georgetown, Bodden Town, East End, and the North
Side zones are considered to be areas with moderate exposure. The remainder of the
country has low exposure to hazards.
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Nat Hazards
8 Conclusions
Today, the economy of Cayman Islands is based upon two main pillars: financial services
and tourism. Determining the level of exposure of the islands to natural and man-made
hazards for development plans and land usage regulations is necessary. Mitigation projects
should be performed from a multi-hazard (hurricanes, earthquakes, tsunamis, and manmade hazards) perspective considering the different qualitative levels of physical vulnerability for the four exposed areas identified here:
• Area 1: North Sound, Little Sound, and Eastern West Bay: Very high vulnerability.
• Area 2: Central Mangroves, Central Bodden Town, Central George Town, and West
Bay: High vulnerability.
• Area 3: Northwestern West Bay, Western Georgetown, Bodden Town, East End, and
the North Side: Moderate vulnerability.
• Area 4: Remainder of country: Low vulnerability.
We consider that the hazard identification and ranking obtained here are the same for
GC, CB, and LC. The hazard risk areas that were identified for GC can be determined in the
same manner for CB and LC if the appropriate information is collected and structured. In
fact, as discussed above in the case of GC, the earthquake hazard risk would be the same
for the three islands. A natural continuation of this work would be a future quantitative risk
analysis of the Cayman Islands. The results presented here are meant to provide the basis
for this future quantitative assessment of risk.
Acknowledgments The authors are grateful to two anonymous reviewers for their thoughtful review of
this work and providing helpful comments. We also thank B. Carby for her feedback in the development of
this study. Special thanks are due to F. McCleary for his assistance and support during this work. J. Chacon
provided information on the meteorological hazards of the Cayman Islands. Our appreciation to the staff of
the Hazard Management Cayman Islands that made this study possible and who kindly provided their
expertise, time, and data. We thank the staff of the various departments and offices of the government of the
Cayman Islands who provided information, comments, and helpful discussions for the development of this
study. E. Zúñiga provided help for preparing the figures.
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