December 22, 2003 San
Simeon Earthquake
Rakesh K. Goel, PhD, PE
Professor, CE & ENVE
Cal Poly, San Luis Obispo, CA
Email: [email protected]
Acknowledgement
Sam Vigil, Cal Poly, SLO
„
Post-earthquake reconnaissance and Photos
Garret Hall, Cal Poly, SLO
Khalid Mosalam, UC Berkeley
Josh Marrow, SGH
Lew Rosenberg, SLO County Geologist
United State Geological Survey (USGS)
California Integrated Seismic Network (CISN)
The Tribune (San Luis Obispo, CA)
©R. K. Goel
San Simeon Earthquake
Slide No. 2
Outline
Seismology
Ground Motion
Performance of Structures
„
„
„
„
Paso Robles
Atascadero
Oceano
San Luis Obispo
Performance of Wineries
©R. K. Goel
San Simeon Earthquake
Slide No. 3
The Ground Shakes
A moderate earthquake of Magnitude 6.5 strikes the
Central Coast of California on December 22, 2003 at
11:15:56 AM local time
„ 2 confirmed dead
„ 40 injured in Paso Robles/Templeton area.
„ 1 building collapsed and more than 40 severely
damaged in Paso Robles Area
„ Atascadero City Hall damaged and closed for
operations.
„ Estimated loss to be equivalent of $200 millions
©R. K. Goel
San Simeon Earthquake
Slide No. 4
Seismological Aspects
©R. K. Goel
San Simeon Earthquake
Slide No. 5
Magnitude of an Earthquake
Local or Richter Scale, ML
„
„
Based on measurements on a Wood-Anderson seismometer
located 100 km from the epicenter
Not appropriate for measuring large earthquakes
Surface Wave Magnitude, Ms
„
„
Based on measurements of surface waves (Rayleigh)
Best for measuring shallow earthquakes at large epicentral
distance
Moment Magnitude, Mw
„
„
Based on seismic moment that depends on the rock rupture
strength, area of rupture, and amount of slip
Considered to be best for measuring large earthquakes
©R. K. Goel
San Simeon Earthquake
Slide No. 6
Relationship Between
Different Scales
The Richter (or
Local) scale
saturates at about 7
The Surface Wave
Magnitude saturates
at about 8
The Moment
Magnitude scale
does not saturate
©R. K. Goel
San Simeon Earthquake
Figure: Kramer, Prentice Hall,
1996
Slide No. 7
Magnitude of the Earthquake
Moment Magnitude of the San Simeon
earthquake estimated by USGS: Mw = 6.5
This magnitude is indicative of energy
released by rupture of the fault
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„
„
Indicates damage potential in the epicenter region
Does not mean that a region far from the
epicenter, e.g., San Luis Obispo City, also
experienced the same magnitude earthquake
Intensity scale (e.g., Modified Mercalli Scale is
more indicative of damage potential in different
areas.
©R. K. Goel
San Simeon Earthquake
Slide No. 8
Intensity Scale: Modified
Mercalli Scale
Indicates how much shaking was felt in any
location from same magnitude earthquake
Scale from I to XII
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„
I = not Felt
V = felt by everyone, objects overturned, no
structural damage
VII = considerable damage to poorly designed
(e.g., unreinforced masonry) construction
XII: total destruction
Different intensity scale noted for different
locations for the same earthquake
©R. K. Goel
San Simeon Earthquake
Slide No. 9
Intensity Scale for San Simeon
Earthquake
VII: Atascadero,
Cambria, Cayucos,
Los Osos, Morro Bay,
Nipomo, Oceano,
Paso Robles, San
Miguel, San Simeon,
and Templeton
VI: at Arroyo Grande,
Grover Beach,
Guadalupe, Pismo
Beach, San Luis
Obispo, Santa
Margarita and Santa
Maria
©R. K. Goel
San Simeon Earthquake
Information: USGS
Slide No. 10
Faults in central Coast
Seismic hazard to
central coast of
California
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HosGri Fault
Cambria Fault
Oceanic Fault
San Simeon Fault
Rinconada Fault
San Andreas Fault
Information: USGS
©R. K. Goel
San Simeon Earthquake
Slide No. 11
San Simeon Earthquake
Epicenter
11 km (6 miles) NE
(49°) from San Simeon
17 km (10 miles) N
(356°) from Cambria
20 km (13 miles) W
(260°) from Lake
Nacimiento
39 km (24 miles) WNW
(283°) from Paso
Robles
Depth of 6.7 km (4.7
miles)
©R. K. Goel
San Simeon Earthquake
Information: USGS
Slide No. 12
Epicenter
The epicenter is the
point on the earth's
surface vertically
above the
hypocenter (or
focus), point in the
crust where a
seismic rupture
begins.
Information: USGS
©R. K. Goel
San Simeon Earthquake
Slide No. 13
Fault at “Fault”
Exact location is
currently unknown
but northern portion
of Oceanic Fault is
the likely candidate
No surface rupture
found
Information: USGS
©R. K. Goel
San Simeon Earthquake
Slide No. 14
Prior Earthquake in Vicinity of
San Simeon
M5 to M6 (?) earthquake in 1853
M5.7 earthquake in 1906
ML6.2 in 1952
Current earthquake of Mw = 6.5 in 2003
Is there a pattern of significant event about
every 50 year?
©R. K. Goel
San Simeon Earthquake
Slide No. 15
Fault Types
Strike–Slip
„
Horizontal motion
between two plates
Normal
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„
Vertical motion with side
above the incline sliding
down
Due to tension between
two sides
Reverse or Thrust
„
„
Vertical motion with side
above the incline sliding
up
Due to compression
between two sides
©R. K. Goel
San Simeon Earthquake
Slide No. 16
Strike-Slip or Thrust
Motion between Pacific-North American
plate in California is primarily strike-slip
A few compression zones also exist
©R. K. Goel
San Simeon Earthquake
Slide No. 17
San Simeon Earthquake
The earthquake
occurred on a thrust
(or reverse) fault
zone
Thrust events build
the coastal
mountain ranges of
central coast of
California.
http://www3.uakron.edu/geography/lrb/physf97/lectures/platetect/sld031.htm
©R. K. Goel
San Simeon Earthquake
Slide No. 18
Recorded Motions
©R. K. Goel
San Simeon Earthquake
Slide No. 19
Recorded Accelerations
Station Name
Station Network
No./ID
Cambria – Hwy 1 Bridge
San Antonio Dam
Templeton – 1-story Hospital
Parkfield – Vineyard Canyon
Los Osos – Point Buchon
San Luis Obispo - Rec Ctr
37737
36258
36695
36441
36427
01083
CGS
CGS
CGS
CGS
CGS
USGS
Dist.
(km)
13
22
38
49
52
62
Horiz Apk (g)
Ground Struct.
.179
-.12
.22
.483
1.28
.09
-.09
-.165
--
Information: CISN
©R. K. Goel
San Simeon Earthquake
Slide No. 20
Motions in San Luis Obispo
Information: CISN
©R. K. Goel
San Simeon Earthquake
Slide No. 21
Motions in Templeton
Information: CISN
©R. K. Goel
San Simeon Earthquake
Slide No. 22
Directivity Effects
Motion in Templeton, which is 38 km from
the epicenter, are larger than in Cambria,
which is only 13 km from the epicenter?
„
Peak horizontal ground accelerations are 0.48g in
Templeton and 0.18g in Cambria
Larger motion in Templeton is due to
directivity effects
„
„
Fault rupture started at the epicenter and
progressed South-East towards Templeton
Larger accelerations occur in the direction of fault
rupture due to Doppler-Type effects
©R. K. Goel
San Simeon Earthquake
Slide No. 23
Comparison with Design Code
Information: CISN
©R. K. Goel
San Simeon Earthquake
Slide No. 24
Structural Performance
©R. K. Goel
San Simeon Earthquake
Slide No. 25
Locations of Major Cities
http://www.slocoupons.com/maps_1.htm
©R. K. Goel
San Simeon Earthquake
Slide No. 26
Structural Performance
Overview
Significant structural damage in Historic
Downtown district of Paso Robles
Significant nonstructural damage in
Templeton and Atascadero
Minor to moderate nonstructural/geotechnical
damage in Oceano
Minor nonstructural damage in San Luis
Obispo
©R. K. Goel
San Simeon Earthquake
Slide No. 27
Damage in Paso Robles
©R. K. Goel
San Simeon Earthquake
Slide No. 28
Damage in Paso Robles
Major damage in
three blocks of
historic downtown
district of Paso
Robles
„
Bounded by 12th and
13th streets in eastwest direction, and
Spring and Railroad
Streets in the northsouth direction
©R. K. Goel
San Simeon Earthquake
Slide No. 29
Damage in Paso Robles
Red-tagged buildings
on
„
„
12th street between
Spring and Pine
Streets
Park Street between
12th and 13th Streets
Yellow-tagged
buildings on
„
Other streets of the
three-block area
©R. K. Goel
San Simeon Earthquake
Slide No. 30
Observations on Damage
Pattern
Unreinforced masonry buildings suffered the
most damage
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Many such buildings are more than 100 years old
Not designed for seismic loads
Lack detailing to transfer seismic forces from
structure to the foundation
Unreinforced masonry buildings have been
known to be seismically vulnerable
„
State and local codes require retrofit but the
deadline was 2008 to 2018
©R. K. Goel
San Simeon Earthquake
Slide No. 31
Acorn Building
Located in historic
downtown Paso
Robles
Housed the
landmark Clock
Tower
Two Story
Unreinforced
Masonry building
Built in 1892
Photo: Paso Robles Chamber of
Commerce
©R. K. Goel
San Simeon Earthquake
Slide No. 32
Acorn Building: After
Photo: Rakesh Goel
©R. K. Goel
San Simeon Earthquake
Slide No. 33
Acorn Building
Roof was not tied
properly to the walls
East-west motion of the
roof imposed large
deformations on the
outer wall in second
story
Second story wall
collapsed
The roof slides to the
side, bends over the
first floor wall, and
crushes cars and two
victims
©R. K. Goel
Photo: The Tribune (1/24/03), SLO, CA
San Simeon Earthquake
Slide No. 34
Acorn Building
Photo: Rakesh Goel
Photo: Rakesh Goel
Photo: Josh Marrow
©R. K. Goel
San Simeon Earthquake
Slide No. 35
Marlow Interior Building
Located on corner of
12th and Park Street
Large open windows
on 12th and Park
Street sides of the
building
Solid walls with few
openings on other
two sides
©R. K. Goel
San Simeon Earthquake
Photo: Josh Marrow
Slide No. 36
Marlow Interior Building
Significant asymmetry
in building plan
„
Torsional motions during
shaking
Significant cracks in
walls facing the street
sides
„
Large demands on these
walls due to torsion
Photo: Sam Vigil
©R. K. Goel
San Simeon Earthquake
Slide No. 37
Marlow Interior Building
Photo: Sam Vigil
Photo: Sam Vigil
Photo: Sam Vigil
©R. K. Goel
San Simeon Earthquake
Slide No. 38
Bistro Laurent Building
Located on corner of
12th and Pine Streets
One story
unreinforced
masonry building
Retrofitted by tying
roof diaphragm to
the walls
©R. K. Goel
San Simeon Earthquake
Photo: Rakesh Goel
Slide No. 39
Bistro Laurent Building:
Retrofit Details
Photo: Rakesh Goel
©R. K. Goel
San Simeon Earthquake
Photo: Rakesh Goel
Slide No. 40
Bistro Laurent Building
Only minor to
moderate structural
damage
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No cracks in the
masonry walls
Few bricks from the
decorative parapet
separated
Building was only
yellow tagged
©R. K. Goel
San Simeon Earthquake
Photo: Rakesh Goel
Slide No. 41
Ali’s Persian Rug Building
Located on the
corner of Park and
13th Streets
Formerly housed
Bank of Italy
Three-story
unreinforced
masonry building
Built in 1918
©R. K. Goel
San Simeon Earthquake
Photo: Khalid Mosalam
Slide No. 42
Ali’s Persian Rug Building
Damage to unreinforced
masonry façade and
parapets
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No ties between façade
and the main wall
Bricks peeled due to outof-plane motion and
stresses imposed on the
joints due to drift
Building red-tagged
©R. K. Goel
San Simeon Earthquake
Photo: Khalid Mosalam
Slide No. 43
Ali’s Persian Rug Building
Photo: Sam Vigil
Photo: Sam Vigil
Photo: Sam Vigil
©R. K. Goel
San Simeon Earthquake
Slide No. 44
Ali’s Persian Rug Building:
Repair (1/18/04)
Photo: Rakesh Goel
Photo: Rakesh Goel
Photo: Rakesh Goel
©R. K. Goel
San Simeon Earthquake
Slide No. 45
Rustic Ranch Furniture Gallery
Unreinforced
masonry building
sandwiched between
two other buildings
No structural
damage apparent
except for broken
window glass
Photo: Rakesh Goel
©R. K. Goel
San Simeon Earthquake
Slide No. 46
Rustic Ranch Furniture Gallery
Photo: Rakesh Goel
Photo: Rakesh Goel
©R. K. Goel
San Simeon Earthquake
Slide No. 47
Paso Robles Inn
Observation tower did
not suffer damage
„
Brick façade supported
on space frame
One of the unreinforced
masonry building
housing quest quarters
was damaged
„
Significant cracks in walls
Moderate nonstructural
damage
„
Photo: Rakesh Goel
Broken window glass
©R. K. Goel
San Simeon Earthquake
Slide No. 48
Paso Robles Inn
Photo: Rakesh Goel
Photo: Sam Vigil
Photo: Rakesh Goel
©R. K. Goel
San Simeon Earthquake
Slide No. 49
Paso Robles Inn: Precaution
Photo: Rakesh Goel
Photo: Rakesh Goel
On 12/23/03
©R. K. Goel
On 1/18/04: Boarded-Up
San Simeon Earthquake
Slide No. 50
Carnegie Library
Photo: Rakesh Goel
Photo: Rakesh Goel
Photo: Rakesh Goel
©R. K. Goel
San Simeon Earthquake
Slide No. 51
City Hall Parking Lot: Rupture
of Sulfur Springs
Photo: Rakesh Goel
Photo: Rakesh Goel
Photo: Rakesh Goel
©R. K. Goel
San Simeon Earthquake
Slide No. 52
Sulfur Spring
Photo: Rakesh Goel
Photo: Rakesh Goel
On 1/18/04
Photo: Rakesh Goel
©R. K. Goel
San Simeon Earthquake
Slide No. 53
Damage in Atascadero
©R. K. Goel
San Simeon Earthquake
Slide No. 54
Atascadero City Hall
Reinforced concrete
space frame
Brick façade
Built in 1918 by
town founder E. G.
Lewis
Partially retrofitted
©R. K. Goel
San Simeon Earthquake
Photo: Rakesh Goel
Slide No. 55
Atascadero City Hall
Photo: Lew Rosenberg
©R. K. Goel
San Simeon Earthquake
Slide No. 56
Atascadero City Hall
Brick façade peeled
off the rotunda
Moderate cracking in
interior partition
walls
City Hall has been
closed
Photo: Rakesh Goel
©R. K. Goel
San Simeon Earthquake
Slide No. 57
Atascadero City Hall
Retrofit prevented parapet collapse
Photo: Rakesh Goel
©R. K. Goel
San Simeon Earthquake
Slide No. 58
Atascadero City Hall
Hazard from falling bricks
Photo: Rakesh Goel
Photo: Sam Vigil
©R. K. Goel
San Simeon Earthquake
Slide No. 59
Atascadero City Hall
Typical nonstructural damage
Photo: Rakesh Goel
Photo: Rakesh Goel
©R. K. Goel
San Simeon Earthquake
Slide No. 60
Typical Damage to Contents
Photo: Rakesh Goel
Photo: Sam Vigil
©R. K. Goel
San Simeon Earthquake
Slide No. 61
Damage in Oceano
©R. K. Goel
San Simeon Earthquake
Slide No. 62
Damage in Oceano
Pavement damage at Oceano airport
Sink holes and damage to tanks at
Waste Water Treatment plant
Damage to houses close to the beach
„
Shifting off the foundation
More than 30 water main break
Street pavement damage
©R. K. Goel
San Simeon Earthquake
Slide No. 63
Damage in Oceano
Damage typical of lateral spreading/
loose sandy soils
Photo: Lew Rosenberg
Pavement Damage
©R. K. Goel
Photo: Lew Rosenberg
House Damage
San Simeon Earthquake
Slide No. 64
San Luis Obispo
©R. K. Goel
San Simeon Earthquake
Slide No. 65
San Luis Obispo (SLO)
More than 125 unreinforced-masonry
buildings in downtown area
About 25 have been seismically upgraded
No significant structural damage reported
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Accelerations were about 17%g in SLO compared
to perhaps more than 50%g in Paso Robles
Performance of unreinforced-masonry buildings in
SLO would not be significantly different than in
Paso Robles if the shaking in SLO had been
stronger
©R. K. Goel
San Simeon Earthquake
Slide No. 66
San Luis Obispo
Photo: Rakesh Goel
Historic Ah Louis Store
survived with minor damage
©R. K. Goel
Photo: Rakesh Goel
Mission San Luis Obispo de
Tolosa came out with only
a minor crack
San Simeon Earthquake
Slide No. 67
Damage to Templeton Area
Wineries
©R. K. Goel
San Simeon Earthquake
Slide No. 68
Damage to Wineries
Wineries along Hwy 46 west of Templeton
sustained heavy nonstructural damage
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damaged glasses and bottles of wine in tasting
facilities
broken bottles in the valuable wine libraries
ruptured stainless steel wine tanks
collapse of wine barrels stacked in pyramids and
on portable steel racks
rupture of wine barrels and loss of a substantial
amount of wine
©R. K. Goel
San Simeon Earthquake
Slide No. 69
Damage to Wineries
Photo:Josh Marrow
Photo:Josh Marrow
©R. K. Goel
San Simeon Earthquake
Photo:Josh Marrow
Slide No. 70
Damage to Wineries
Photo:Josh Marrow
Photo:Josh Marrow
Photo:Josh Marrow
©R. K. Goel
San Simeon Earthquake
Slide No. 71
Conclusion and Lessons
Unreinforced masonry (URM) buildings are
highly susceptible to seismic loading
„
„
Potential for collapse
Significant hazard from falling bricks from façade
Even basic seismic retrofit – tying floor/roof
diaphragm to walls – minimized the collapse
potential for URM building
„
„
San Simeon earthquake tested several retrofitted
buildings in Paso Robles
Most retrofitted buildings survived without major
damage
©R. K. Goel
San Simeon Earthquake
Slide No. 72
Conclusion and Lessons
Buildings on street corners performed poorly
„
„
Asymmetric in building plan due to large open
windows on street sides
Torsional motions impose larger demands on
lateral load resisting elements during earthquake
Buildings at the end of the block performed
poorly compared to similar buildings in midblock
„
„
End buildings gets kicked out by neighboring
building
Need special attention during retrofit
©R. K. Goel
San Simeon Earthquake
Slide No. 73