PROTOCOL IN RELEASING VOLCANO
INFORMATION
PHIVOLCS
Kanlaon Volcano
monitoring network
Prepared by
Esfeca T. del Mundo
Jaime S. Sincioco
Technical Advisers
Renato U. Solidum, Jr
Ernesto G. Corpuz
Ma. Mylene Martinez-Villegas
Production Staff
Ester Garrido
Angelito De Guzman
Richard Ballon
Ruben Lamela
First Printed: October 2003
Revised: June 2006
DEPARTMENT OF SCIENCE AND TECHNOLOGY
PHILIPPINE INSTITUTE OF VOLCANOLOGY AND SEISMOLOGY
PHIVOLCS Website:
www.phivolcs.dost.gov.ph
MONITORING ACTIVITY AT KANLAON
VOLCANO
Kanlaon Volcano is being monitored by three
permanent stations. The Canlaon City Observatory
is located 8.7 km ESE of the summit. Five and a
half kilometers south is the Cabagnaan Seismic
station while at the western side is the Guintubdan
Station. During crisis, additional seismic stations
are installed at Mananawin, Mambucal and Masulog
to augment these stations.
In addition to seismic and visual observations,
ground deformation surveys are conducted regularly
to
determine tilting and swelling of the volcanic
edifice. Electronic Distance Measurement (EDM)
lines are surveyed from Kanlaon Volcano
Observatory to upper and middle slopes of the
volcano and from Cabacungan to Cabagnaan. A
precise leveling line at Guintubdan is also
reoccupied every now and then. Ground Positioning
Satellite (GPS) stations are located at Guintubdan
and Canlaon City to measure ground movements.
Electronic tiltmeters are also installed on the slopes
of the volcano as another method to detect ground
deformation.
Of the 22 active volcanoes in the Philippines, the
Philippine Institute of Volcanology and Seismology
(PHIVOLCS) is closely monitoring six of them.
PHIVOLCS employs several techniques in
monitoring them.
benchmarks due to volcanic forces acting
underneath. Changes in vertical and horizontal
ground surface strains are usually related to magma
intrusion and these changes could be carefully
measured using precise leveling instruments.
VISUAL AND OTHER SENSORY
OBSERVATIONS
An inflating volcano edifice may also exhibit
other visually detectable signs such as steeped
slopes, frequent occurrences of rockfalls, landslides
and debris slides, formation of ground fissures,
drying up of water wells and springs and decreasing
lake levels (for crater lakes).
Volcanologists are always on the alert for
unusual events, changes and emanations that could
be seen, felt, heard or smelled from active crater of a
volcano and on its slopes. These events are changes
in color, height and volume of steam emission,
occurrences of crater glow, rumbling and explosive
sounds, rockfalls and landslides and sulfurous odors.
SEISMIC OBSERVATIONS
Seismic monitoring is one of the major tools in
predicting eruption. All volcano observatories in the
Philippines rely on an array of short-period
seismometers to keep track of the number of events
occurring daily. As magma rises and forces its way
through fissures, it causes ground vibrations which
are recorded by seismographs as volcanic
earthquakes. A volcano’s seismic network detects
earthquakes for accurate location and classification.
components into the existing strata. The ground and
the associated springs are also affected by magma
forcing its way to the surface. Thus, systematic
measurements of springs and water wells may reflect
some ground deformation related to volcanic
activity. Increase in emission rates of some gases in
volcanic plumes such as Sulfur Dioxide is also
measured
using
Correlation
Spectrometer
(COSPEC) to detect anomalous volcanic activity.
Remote COSPEC measurements are made with
the instrument mounted in a fixed winged aircraft
with the periscope positioned vertically outside the
aircraft or mounted at the back of a vehicle for land
traverse. The instrument is allowed to pass under
the plume to measure the gas content. If the width
of the volcanic plume is small, COSPEC is mounted
on a tripod and the periscope is positioned at angles
covering the entire plume.
WARNING SYSTEM
PHIVOLCS monitoring team conducting EDM survey at
Kanlaon Volcano Observatory
A volcano Alert Level Scheme was designed for
use in information dissemination regarding the
condition of the volcano. The alert status is included
in volcano updates or bulletins issued to inform not
only the disaster coordinating agencies but also the
public.
Below is the Alert Level scheme for
Kanlaon Volcano.
Shortening of slope distance measured by EDM
(distance between instrument and reflector) may
indicate that the volcano edifice is inflating due to
magma intrusion. EDM survey is conducted more
frequently during crisis. A precise leveling survey
measures elevation changes between established
ALERT
No Alert/
Alert Level
Zero
(NORMAL)
Volcanic activity is at
its background level.
2
Elevated
Level of
Volcanic
Unrest
Elevated levels of any
of the following:
seismic, fumarolic
and/or other volcanic
activity. Repeated ash
ejections.
Seismic swarms,
tremor and high level
of other monitored
parameters. More
energetic and more
frequent steam/ash
ejection.
Intense unrest which
may be characterized
by frequent periods of
high frequency and
low frequency
volcanic quakes,
tremors, some felt;
vigorous steam/gas
discharge from crater.
Summit
incandescence, lava
dome.
Hazardous eruption in
progress with
billowing tall ashladen eruption clouds
and/or pyroclastic
flows/lava flows.
Lahars.
3
High Level of
Volcanic
Unrest
Temperature changes of identified hot spots, hot
springs, wells and crater lakes are regularly
monitored. Abrupt changes or increasing trends may
indicate an impending eruption.
Geochemical monitoring of active volcanoes
involves measuring the changes in chemical
composition of crater lakes, hot springs and
fumaroles. Such changes occur because magma that
intrudes the surrounding rock imparts chemical
Background level, no
unusual activity
Slightly elevated
levels of seismic,
fumarolic and/or other
volcanic activity.
Isolated steam bursts
or ash ejections.
THERMAL MEASUREMENTS
5
Alert Level 5
(LifeThreatening
ERUPTION)
GEOCHEMICAL MONITORING
CRITERIA
1
Slight Unrest
4
Eruption
Imminent
GROUND DEFORMATION
The rising magma beneath an active volcano
causes an upward push and produces swelling or
inflation of the volcanic edifice. This inflation can
be measured by Electronic Distance Meter (EDM),
water tube and electronic tiltmeters, precise leveling
instruments and by Global Positioning System
(GPS).
KANLAON VOLCANO ALERT SCHEME
Precise levelling survey conducted by PHIVOLCS
monitoring team at Guintubdan
Revised, 14 April 2005
INTERPRETATION/RECOMM
ENDATION
No eruption is indicated.
However, there are associated
risks when venturing within the
Permanent Danger Zone
(PDZ), defined as a circular
area with the crater at the
center and swept by a radius of
four (4) kilometers. The
volcanic hazards associated
with these risks could include
steam bursts or ash ejections
which may occur suddenly and
without perceptible precursors
or warning.
May lead to more steam and
ash ejections which affect the
crater and summit area only.
The source of activity is
shallow, near crater. No
magmatic activity is indicated.
No entry within the Four (4)
kilometer radius PDZ.
Probable ascent and intrusion
of magma. Events could lead
to hazardous eruption. No entry
within the Four (4) kilometer
radius PDZ.
Magmatic processes underway.
Events could lead to hazardous
eruption. Danger Zone
extended to at least SIX (6)
kilometers radius from the
active crater
Gas-charged magma is close to
or at crater surface. Hazardous
eruption is likely, possibly within
hours or days.
Danger Zone extended to TEN
(10) kilometers radius.
Hazardous eruption in
progress. Flowing or falling
materials encroach into
settlements.
If there is reason to believe that
explosive eruption shall
intensify, the Danger Zone may
be extended to 14 kilometers.