5/31/2022
REALITIES IN THE PHILIPPINES
o
o
o
o
RP’s geographical location
RP as an archipelagic country
Emerging global concerns
Limited resources
The Philippines is one of
the most disaster-prone
countries in the world !!!
Photos:www.google.com
2
1
5/31/2022
Types of Disasters (CRED)
1. Climatological – events caused by long-lived/meso to macro scale
processes (in the spectrum from intra-seasonal to multi decadal climate
variability i.e., extreme temperature, drought
Photos:www.google.com
3
Types of Disasters (CRED)
2. Biological – disaster caused by the exposure of living organism to germs
and toxic substances i.e., epidemic, insect infestation
Photos:www.google.com
4
2
5/31/2022
Types of Disasters (CRED)
3. Hydrological - events caused by deviations in the normal water cycle and/or
overflow of bodies of water caused by wind set-up e.g., flood
Flashflood during Typhoon
Pablo that wiped out entire
community, Compostela Valley,
2012
Photo:www.google.com
Photo:www.google.com
Severe Flooding During
Habagat, Manila, 2012
Heavy Rains Caused
Landslide, Cherry Hills,
Antipolo City, 1999
Photo:wslopez
5
Types of Disasters (CRED)
4. Meteorological – events caused by short-lived/small to meso scale
atmospheric processes (in the spectrum from minutes to days) e.g.,
typhoon
Typhoon Reming, Albay, 2006
Typhoon Milenyo, MM, 2006
Photo:dpwh tfbbi,2006
Photo:www.google.com
6
3
5/31/2022
Types of Disasters (CRED)
5. Geophysical – events originating from solid earth e.g., volcanic eruption,
earthquake
July 16, 1990 M7.8 EQ, Baguio City, 1990
Photo:www.google.com
Mt. Pinatubo Eruption, 1991
7
Geologic Setting
8
4
5/31/2022
Geologic Setting
The earth’s
outermost shell
consists of large
blocks called
tectonic plates,
which drift and
move with respect
to each other, at the
rate of several
centimeters/year.
Earth’s Interior
9
Major tectonic plates
Continental Tectonic Plates
Eurasian
North
American
Pacific
IndianAustralian
African
South
American
Antarti
c
(From Plummer et al 1997, as modified from W. Hamilton , USGS)
10
5
5/31/2022
Earthquake Facts
1. Largest EQ since 1900 – May 22, 1960 Valdivia M9.5 EQ, Chile
Hawaii
Photos from USGS
Japan
11
Earthquake Facts
2. Deadliest EQ since 1900 – December 2004 M 9.1 Sumatra EQ
- 283,106 deaths
Photo courtesy of Dr. Pennung Warnitchai, Asian Institute of Technology
12
6
5/31/2022
Earthquake Facts
3. Deadliest EQ ever recorded – January 23, 1556 Shaanxi EQ,
China with M> 8.0 - 830,000 deaths
Other Deadly EQ’s in China:
1976 M7.5 EQ - 250,000 deaths
1927 M7.9 EQ - 200,000 deaths
1920 M7.8 EQ - 200,000 deaths
13
Philippine Geological Setting
The Philippine Archipelago
occupies the western ring of the
Pacific Ocean (Western
Segment of the Pacific Ring of
Fire), a most active part of the
earth that is characterized by an
ocean-encircling belt of active
volcanoes and earthquake
generators (faults).
SQUEEZED!
Source: USGS
14
7
5/31/2022
15
Earthquake Activity in the Philippines
▪ 20 earthquakes recorded per day
▪ ~ 200 earthquakes felt per year
▪ ~ 90 destructive earthquakes in
400 years
▪ ~ 40 tsunamis in 400 years
Source: PHIVOLCS
16
8
5/31/2022
1990 M7.8 Luzon EQ
1968 M7.3 Casiguran EQ
1994 M7.9 Mindoro EQ
Damages due to past seismic events
1976 M7.9 S. Cotabato EQ
17
2012 M6.9 Negros EQ
2013 M7.2 Bohol EQ
2017 M6.5 Leyte EQ
Damages due to past seismic events
2017 M6.7 Surigao EQ
18
9
5/31/2022
Because the Philippines is located in a region
with very high seismicity , then we have a
very high SEISMIC RISK !!
Photo courtesy of Engr. Lito Lanuza, Phivolcs
19
Seismic Risk Defined
Seismic Risk – probability that social or economic consequences of
earthquakes will equal or exceed specified values at a site, at several
sites, or in an area, during a specified exposure time. (EERI)
20
10
5/31/2022
Seismic Risk Defined
Seismic Risk – probability that social or economic consequences of
earthquakes will equal or exceed specified values at a site, at several
sites, or in an area, during a specified exposure time. (EERI)
Seismic Hazards
21
Seismic Risk Defined
Seismic Risk – probability that social or economic consequences of
earthquakes will equal or exceed specified values at a site, at several
sites, or in an area, during a specified exposure time. (EERI)
Seismic Hazards
Vulnerability
22
11
5/31/2022
Seismic Risk Defined
Seismic Risk – probability that social or economic consequences of
earthquakes will equal or exceed specified values at a site, at several
sites, or in an area, during a specified exposure time. (EERI)
Seismic Hazards
Vulnerability
Exposure
23
Seismic Risk Defined
Seismic Risk – probability that social or economic consequences of
earthquakes will equal or exceed specified values at a site, at several
sites, or in an area, during a specified exposure time. (EERI)
Seismic Hazards
Location
Vulnerability
Exposure
24
12
5/31/2022
Seismic Risk Defined
RISK FACTORS
Seismic Hazards
Vulnerability
Exposure
SEISMIC RISK
Location
Seismic Risk = f (Hazard, Vulnerability, Exposure, Location)
25
Hazards Defined
Hazard–physical phenomenon that may produce adverse
effects to human activities - life, health, property,
environment. It may be dormant or potential.
Seismic Hazards:
Geologic hazards: ground shaking, fault rupture,
landslides, liquefaction
Tsunami
Fire
26
13
5/31/2022
Effects of Seismic Hazards
1. Ground Shaking
27
• Ground Shaking Effects: Buildings Collapse
University of Baguio
Siesta Inn
Photos: DPWH-JICA Study
Team, 1990 M7.8 Luzon EQ
Nevada Hotel
Sky World Hotel, Baguio City,
(photo:google.com)
28
14
5/31/2022
• Ground Shaking Effects: Buildings Collapse
2013 M7.2 Bohol EQ
2017 M6.5 Leyte EQ
2017 M6.7 Surigao EQ
2012 M6.9 Negros EQ
Photos: ASEP
29
• Ground Shaking Effects: Sequential Earthquakes
The 2019 Cotabato
Earthquakes
source: phivolcs
30
15
5/31/2022
• Ground Shaking Effects: Sequential Earthquakes
The 2019 Cotabato Sequential Earthquakes
These series of earthquakes originated from the Cotabato Fault System with
epicenters within Tulunan, Cotabato.
Oct. 16, 2019 - 7:37 PM - M6.3 and a depth of 9.0 km
Oct. 29, 2019 - 9:04 AM - M6.6 and a depth of 7.0 km
Oct. 29, 2019 - 10:42 AM - M6.1 and a depth of 9.0 km
Oct. 31, 2019 - 9:11 AM - M6.5 and a depth of 8.0 km
Shallow earthquakes = 0 to 70 km
Intermediate earthquakes = 70 to 300 km
Deep earthquakes = 300 to 700 km
source: phivolcs
source: usgs
31
Ground Shaking Effects: Building Damage due to series of earthquakes
Ecoland 4000 –Davao City
before the M6.5 October 31,
2019 (photo:google.com)
Ecoland 4000 after the M6.5
October 31, 2019
(Photo: Mr Cardio Ped Don)
32
16
5/31/2022
Ground Shaking Effects: Building Damage due to series of earthquakes
Eva Hotel after the M6.3 Oct.
29, 2019 EQ (photo: Engr. G.
Magbutay)
Eva Hotel after the M6.5
October 31, 2019 EQ (photo:
Engr. G. Magbutay).
Eva Hotel before Oct. 16, 2019
EQ (photo: google.com)
33
• Ground Shaking Effects: Bridges Collapse
Photo: ASEP
2017 M6.7 Surigao EQ
Photo: DPWH TFBBI
2012 M6.9 Negros
34
17
5/31/2022
• Ground Shaking Effects: Bridges Collapse
Photo: Phivolcs
Photo: ASEP
2013 M7.2 Bohol EQ
1990 M7.8 Luzon EQ
35
Collapsed of Hanshin Expressway, M6.9 Kobe EQ 1995 (source: google.com)
36
18
5/31/2022
Effects of Seismic Hazards
2. Ground (Fault) Rupture
Fault Trace in Inabanga, Bohol
Photo:wslopez
Photo:wslopez
2013 M7.2 Bohol EQ
Photo:phivolcs
37
Effects of Seismic Hazards
2. Ground (Fault) Rupture
1990 M7.8 Luzon EQ
38
19
5/31/2022
Ground (Fault) Rupture Effects: Damaged Roadways
1990 M7.8 Luzon EQ
Cagayan Valley Road in
San Jose, Nueva Ecija
photos: DPWH/Katahira
39
Ground (Fault) Rupture Effects: Direct Fault Displacement Damaging Houses
1999 Turkey EQ
From Structural Engineering Reconnaissance of the August 17, 1999, Kocaeli (Izmit), Turkey Earthquake, Pacific
Earthquake Engineering Research Center, Dec. 2000
40
20
5/31/2022
Ground Rupture Effects: Lateral Spreading
Lateral spreading of ground damaging
roadways
photo:DPWH TFBI
2012 M6.9 Negros
photo:ASEP
2013 M7.2 Bohol EQ
41
Effects of Seismic Hazards
3. Landslide : down slope movement of rocks, soil and other debris
commonly triggered by heavy rains or strong earthquake
Effects:
Slope failure-erosion
Burial
Road blockage
Landslides blocking roads, July
16, 1990 M7.8 Luzon EQ
(Kennon Road, Baguio City)
42
21
5/31/2022
Effects of Seismic Hazards:
Landslide/Rockslide/Slope Failure
Kennon Road, 1990 M7.8 EQ
Rockslide due to heavy rains,
Mogpog-Sta. Cruz Road,
Marinduque (photo frm. Reden
Maniquez)
Kennon Road, 2018
(Photo: google.com)
43
Effects of Seismic Hazards:
Landslide/Rockslide/Slope Failure
Photo: DPWH-JICA Study
Team, 1990 Luzon EQ
1990 M7.8 Luzon EQ (Baguio City)
2005 M7.6 Kashmir EQ, Pakistan
(source:google.com)
44
22
5/31/2022
Effects of Seismic Hazards
4. Liquefaction
45
Liquefaction Effects
1990 M7.8 Luzon EQ
(Dagupan City, Pangasinan)
46
23
5/31/2022
Liquefaction Effects : Subsidence /Leaning of Buildings
2013 M7.2 Bohol EQ
photos:ASEP
2017 M6.7 Surigao EQ
47
Liquefaction Effects : Toppling/ Subsidence /Leaning of Buildings
The picture is the most graphic
example and perhaps the most well
known pictorial record of
liquefaction induced damage to
Buildings.
This is in Niigata, Japan.
The Damage consist of:
Toppling
Subsidence
Most of these buildings were supported on Short Friction
Piles. When the surrounding ground liquefied, the piles lost
frictional support.
1964 M7.6 Niigata EQ, Japan
Leaning
Photo from: The Seismic Design Handbook, 2nd Ed.,
Farzad Naeim
48
24
5/31/2022
Effects of Seismic Hazards
5. Tsunami
49
Effects of Seismic Hazards: Tsunami
50
25
5/31/2022
Effects of Seismic Hazards: Tsunami
51
Effects of Seismic Hazards: Tsunami
2004 M9.1 Sumatra EQ
52
26
5/31/2022
Effects of Tsunami
2004 M9.1 Sumatra EQ
Completely destroyed building in
Kuk-Kak Beach, Khao Lak
Photos courtesy of Dr. Pennung Warnitchai,
Asian Institute of Technology
53
Effects of Tsunami
2011 M9.1 Tohoku EQ, Japan
Photos from google.com
54
27
5/31/2022
Tsunami vs. Storm Surge
Roxas Boulevard Seawall: Effect of Habagat
55
Effects of Seismic Hazards:
6. Fire/Explosions
1995 M6.9 Kobe EQ, Japan
6,965 buildings fire- damaged
175 locations
54 simultaneous fires
56
28
5/31/2022
Effects of Seismic Hazards: Fire/Explosions
1999 M7.6 Izmit EQ, Turkey
57
Factors That Influence Seismic Hazards:
Earthquake Damage Mechanism
Degree of Earthquake Damage Depends on:
1. Magnitude or Intensity of the Earthquake
Photo: EDM-EqTap
2013 M7.2 Bohol EQ
58
29
5/31/2022
59
What is Fault ?
- A fracture along which the blocks of crust on either side have
moved relative to one another parallel to the fracture. (Source: ANSS Website)
top: normal fault
center: thrust fault
bottom: strike-slip fault
: direction of
earth’s crustal
stress
Fault movement
generates an
EARTHQUAKE .
*Frm: EDM-EqTAP
60
30
5/31/2022
Magnitude vs. Intensity
Magnitude is a measure of
the total energy released
during the earthquake.
100
watts
Example: 6.1 Richter Scale
(It is analogous to the
wattage of a light bulb.)
61
Magnitude vs. Intensity
Intensity is a description of the
shaking felt at a specific
location during the
earthquake.
Example: PEIS level V (It is
analogous to the intensity of
light from the bulb as
observed at a specific
location.)
EPICENTER
Intensity is inversely proportional
to focal distance.
62
31
5/31/2022
Degree of Earthquake Damage Depends on:
2. Distance From the Earthquake Source
1995 M6.9 Kobe EQ, Japan
63
2013 M7.2 Bohol EQ
Structure situated on top of fault may
suffer severe damage or it may collapse.
PHIVOLCS recommends 5 meter buffer
zones from both sides of fault.
Fault Trace in Catigbian, Bohol
64
32
5/31/2022
This four story building did not suffer damage although located just 2 meters
from the rupture zone – 1999 M7.6 Izmit EQ, Turkey
1.2 m horizontal offset ;
2.35 m vertical offset
From Structural Engineering Reconnaissance of the August 17, 1999, Kocaeli (Izmit), Turkey Earthquake, Pacific
Earthquake Engineering Research Center, Dec. 2000
65
Degree of Earthquake Damage Depends on:
3. Site Response (Site Effects)
Hard rock
Soft ground
Stiff ground
(Source: USGS)
Soft ground shakes more strongly than hard rock
→ Site effect
Loma Prieta, California earthquake in 1989
66
33
5/31/2022
Seismic Risk Defined
RISK FACTORS
Seismic Hazards
Vulnerability
Exposure
SEISMIC RISK
Location
Seismic Risk = f (Hazard, Vulnerability, Exposure, Location)
67
Reducing Seismic Risks by Reducing Vulnerabilities.
Seismic Risk = f (Hazard, Vulnerability, Exposure, Location)
o The effects of earthquake hazards, e.g., soil problems
like liquefaction, strong ground shaking, etc., are
adequately addressed in the National Structural Code
of the Philippines(NSCP).
68
34
5/31/2022
Reducing Seismic Risks by Reducing Vulnerabilities.
Seismic Risk = f (Hazard, Vulnerability, Exposure, Location)
o Also, vulnerability indicators of buildings are stated in
various chapters in the NSCP. Configuration problems
like plan and vertical irregularities are properly
addressed. Provisions on how to treat existing
buildings and avoidance of brittle-type failures and
excessive drift or lateral displacements are also
provided.
69
Reducing Seismic Risks by Reducing Vulnerabilities.
Seismic Risk = f (Hazard, Vulnerability, Exposure, Location)
o Moreover, the NSCP emphasizes that “Structures and
portions thereof shall, as a minimum, be designed and
constructed to resist the effects of seismic ground
motions”.
o The effects of the horizontal and vertical components
of the ground motion are emphasized.
Sufficient guidelines are provided to minimize the effects of seismic hazards and
addressed the vulnerabilities of buildings/structures
70
35
5/31/2022
Implicit Performance Objectives of Traditional Design Codes (SEAOC, 1960)
• Resist minor earthquake, which may occur several times
during the life of the structure, without damage to
structure or nonstructural contents (Frequent EQ).
• Resist moderate earthquake, which may occur one or
more times during the life of the structure, with limited
damage to non-structural components and no significant
damage to structure (Occasional EQ).
• Resist major earthquake without collapse of structure or
damage that would create life-safety hazard (Rare EQ).
Three performance objectives but only one design earthquake. Performance objectives are
non quantifiable. (Rare EQ = 10%/50years)
71
Minimum Design Loads -Earthquake Loads (NSCP 7th Ed. 2015)
Sec. 208.5.3.2 Ground Motion
NSCP2015
Focus of
NSCP8th Ed.
72
36
5/31/2022
Minimum Design Loads -Earthquake Loads (NSCP 7th Ed. 2015)
For Linear Static Procedure (Sec. 208.5.2)
Maximum:
(Eq. 208-9)
(Eq. 208-8)
Minimum: (Eq. 208-10)
𝑉
Additional Minimum for Zone 4:
(Eq. 208-11)
73
Minimum Design Loads -Earthquake Loads (NSCP 7th Ed. 2015)
Seismic Map of the Philippines
The Philippines is divided into two
(2) Seismic Zones :
Seismic Zone 2 (Z=0.2)
Islands of Palawan, Sulu and TawiTawi
Seismic Zone 4 (Z=0.4)
Rest of the Philippine Islands
74
37
5/31/2022
Proposed Seismic Provisions of NSCP 8th Ed. based on ASCE 7-05
Seismic Provisions of ASCE 7-05 is being considered to be
adopted in the proposed NSCP 8th Edition
Issuance of the Philippine Earthquake Model
(PEM) of PHIVOLCS
ASEP Project SAM (Spectral Acceleration Maps)
75
Ground Motions
Codes generally produced design spectrum
For linear structural analysis, response spectrum is all you need- usually no
need for individual ground motions
Seismological Studies
Generalized Response Spectra
for Different Soil Types
Earthquake Engineering
Studies
Structural Engineering
Studies
Idealized Response Spectra
(NSCP 7th Ed 2015)
76
38
5/31/2022
Proposed Seismic Provisions of NSCP 8th Ed. based on ASCE 7-05
𝐶𝑆 =
For Linear Static Procedure:
𝑉 = 𝐶𝑆 𝑊
𝐶𝑆 =
𝑉
𝐶𝑆 =
𝑆𝐷𝑆
𝑅ൗ
𝐼𝑒
𝑆𝐷𝐼 𝑇𝐿
𝑇 2 𝑅ൗ𝐼
𝑒
maximum
𝑆𝐷𝐼
𝑇 𝑅ൗ𝐼
𝑒
maximum
𝐶𝑆 = 0.044𝑆𝐷𝑆 𝐼𝑒 ≥ 0.01
NSCP2015
minimum
77
Proposed Seismic Provisions of NSCP 8th Ed. based on ASCE 7-05
78
39
5/31/2022
NSCP 2015: Design Response Spectra
Design Response Spectra (NSCP2015/ASCE7-05)
Davao: Sa=2.9 S1=1.8
Spectral Acceleration
Benguet: Sa=2.7 S1=1.6
NSCP 2 km
NSCP 5 km
Marikina: Sa=1.7 S1=0.7
NSCP 10 km
ASCE7-05: Design Response Spectra
Period
Comparison of Response Spectra (NSCP2015 & ASCE7-05)
5% Damping, Soil Type D
79
To conclude…….
Seismic hazards are one of the natural hazards that the Philippines is
exposed to. This makes the country at risks of seismic events. Some of the
causes of collapse and/or damage of various structures during the past
earthquakes can be avoided by strictly following the recommended design
and construction provisions of the Codes. Existing old buildings and other
structures should also be assessed. Earthquake disasters cannot be
avoided but their effects can be minimized. Engineers and architects
design and build structures to withstand the tests of time. But safety can
only be assured through proper design, construction, maintenance, and
use. These are the responsibilities of all stakeholders – engineers, builders,
owners, government.
80
40
5/31/2022
To conclude…….
Understanding seismic hazards and the factors that influence these are our
guides to determine appropriate measures to mitigate the effects of such
hazards.
Four levels of intervention to modify, reduce, or prepare for the risks of
seismic event:
1. Halt the earthquake from occurring
2. Avoid areas of high seismicity or move to
seismically-inactive location
3. Predict occurrence of earthquake
4. Prepare for and/or reduce vulnerability
From: Earthquakes: An Architects
Guide to Nonstructural Seismic
Hazards by Henry J. Lagorio, University
of California-Berkeley, 1990
81
Earthquakes don’t kill people….
Buildings do…….
82
41
5/31/2022
Thank You for
your
Attention!!!
Photo:wslopez
83
42