Earthquake Hazards and Risk

Scenario for Metro Manila and

Vicinity: the Need for Whole of

Society Preparedness

May 20, 2015

Renato U. Solidum, Jr.

Philippine Institute of Volcanology and Seismology

Department of Science and Technology

What Happened in Nepal?

2015 April 25 Nepal Earthquake

Time: 2015-04-25 06:11:26 (UTC), Saturday

Magnitude: 7.8

Depth: 15 km

* LAST MOVEMENT OF FAULT SEGMENT = 1344

Nearby Cities

34km (21mi) ESE of Lamjung, Nepal

77km (48mi) NW of Kathmandu, Nepal

Modified Mercalli Intensity

Perceived

Shaking

Extreme

Violent

Severe

Very Strong

Strong

Moderate

Light

Weak

Not Felt

USGS Estimated shaking Intensity from M 7.8 Earthquake

The Modified Mercalli Intensity

(MMI) scale depicts shaking

severity. The area nearest

Katmandu experienced very

strong to severe shaking.

Image courtesy of the US Geological Survey

Shaking Intensity

Magnitude 7.8 NEPAL Saturday, April 25, 2015 at 06:11:26 UTC

Because it is built in a basin underlain by lake

sediment, Kathmandu was particularly

vulnerable during this earthquake. The city is

located in a broad valley surrounded by the

Himalayas. This valley was formerly the site

of a lake within which river delta and lake

sediment accumulated to thickness of about

100 meters.

Magnitude 7.8 NEPAL Saturday, April 25, 2015 at 06:11:26 UTC

Simplified geologic cross-section of the Kathmandu Valley showing basin-fill sediments. Lakebed deposits are

labeled “lacustrine” whereas sediments deposited by rivers are labeled “fluvial”. After Sakai et al. Pleistocene

rapid uplift of the Himalayan frontal ranges recorded in the Kathmandu and Siwalik basins, Palaeogeography,

Palaeoclimatology, Palaeoecology, v. 241, p.1 6–27, 2006.

Summary of Hazards and Impact as of 12 May (Center for Disaster Management and Risk Reduction Technology)

• Well built structures received slight damage. Older buildings

suffered great damage. Ground shaking in epicentral area

corresponds to Intensity VIII.

• Many government, religious and private buildings destroyed.

~ 300,000 destroyed, 250,000 damaged.

• Many landslides blocking roads and causing infrastructure

damage, and limited liquefaction.

• Death toll 8151, 377 missing in Nepal. Around 100 fatalities

in Tibet, India and Bangladesh.

What is the Earthquake Scenario in

Metro Manila and nearby Provinces?

LATEST DAMAGING EARTHQUAKE

IN METRO MANILA

• M 7.3 Casiguran, Aurora

Earthquake, 02 August

1968

• Ruby Tower in Manila

collapsed – 268 killed, 260

injured

EARTHQUAKE GENERATORS IN

METRO MANILA AND VICINITY

THE VALLEY FAULT SYSTEM

• West Valley Fault

(WVF) movement

mainly horizontal

• WVF moved 4 times in

past 1400 years;

movement interval ~

400 years

• Last major earthquake

from Valley Fault in

1658

EARTHQUAKE-RELATED HAZARDS

Tsunami Fire

Ground Shaking Liquefaction

Landslide

Faulting (Ground)

Rupture

Fault

Valley Fault System • East Valley Fault

• 10 km (M6.2) • Municipalities of Rodriguez

and San Mateo, Rizal • West Valley Fault

• 100 km (M7.2) • Bulacan ((Doña Remedios

Trinidad, Norzagaray and San Jose Del Monte City)

• Rizal (Rodriguez) • Quezon City, Marikina City,

Makati City, Pasig City, Taguig City and Muntinlupa City

• Laguna (San Pedro City, Biñan City, Sta. Rosa City, Cabuyao City and Calamba City)

• Cavite (Carmona, General Mariano Alvarez and Silang)

The Valley Fault System (VFS) in Greater Metro

Manila Areas Atlas

• 33 map sheets • Metro Manila

• 1:5,000 (22 map sheets)

• Laguna and Cavite • 1:10,000 (10 map

sheets) • Bulacan and Rizal

• 1:50,000 (1 map sheet)

GROUND SHAKING IN GREATER METRO

MANILA (West Valley Fault Earthquake) (Risk Analysis Project, 2013: PHIVOLCS, GA supported by AusAID)

NCR

BULACAN

RIZAL

CAVITE

LAGUNA

BULACAN

NCR RIZAL

CAVITE

LAGUNA

M6.5 M7.2

INTENSITY VIII (VERY DESTRUCTIVE)

GROUND SHAKING

1995 Kobe Earthquake

BUILDING AND CASUALTY ESTIMATES (1) FOR METRO MANILA FROM A M7.2 WEST VALLEY FAULT EARTHQUAKE

Residential Building (1,325,896)

Damage Heavy -168,300 (12.7%) Partly - 339,800 (25.6%)

Public Buildings

Damage Heavy - 8-10% Partly - 20-25% 10-30 Storey Building

Damage Heavy - 11% Partly - 27%

30-60 Storey

Damage Heavy - 2% Partly - 12%

Population (9,932,560)

Casualty Dead 33,500 (0.3%)

Injured 113,600 (1.1%)

Additional Deaths by Fire 18,000

Metro Manila Earthquake Impact Reduction Study, 2004 – JICA, PHIVOLCS, MMDA

BUILDING AND CASUALTY ESTIMATES (2) FOR METRO MANILA FROM A WEST VALLEY FAULT EARTHQUAKE

Risk Analysis Project, 2013 – PHIVOLCS, UP-ICE, GA (AusAID)

M7.2 M6.5

Total Floor Area in Complete 88,142,000 65,407,000

to Collapsed Damage (sqm)

Total Floor Area in Slight 172,924,000 162,799,000

to Extensive Damage (sqm)

Total Fatalities (Death) 31,000 23,000

Total Injuries Very Serious 14,000 10,000

Serious 112,000 85,171

Slight 385,000 302,000

Total Economic Losses (millions of PhP) 2,269,000 1,773,000

LIQUEFACTION

Subsidence of bridge column Subsidence of building, roads

Dagupan 1990

Fissuring of roads

Mindoro 1994

Dagupan 1990

La Union, 1990

Damage to buried pipes, tanks

(READY for GMMA Project, 2013)

LIQUEFACTION POTENTIAL M7.2 West Valley Fault Earthquake

Localities prone to liquefaction

a) water-saturated (shallow water table), low-lying

b) Have loose

(unconsolidated), sand or silt deposits

• river banks, abandoned

rivers, flood plains

• coastlines

• swamps

• reclaimed land

(MMEIRS, 2004)

FIRE AFTER THE EARTHQUAKE M7.2 West Valley Fault Earthquake

*MMEIRS, 2004

Pasig Manila

Marikina

Muntinlupa

Taguig

Pasay

Paranaque

Las Pinas

Quezon

City

Makati Mandaluyong

Navotas

Malabon Caloocan

Valenzuela

San Juan

Pateros Maximum Burnt Number

500 - 1,000

200 - 500

100 - 200

50 - 100

20 - 50

1 - 20

• Fire outbreak by

electrical short circuit;

toppling of lamps,

candles

• Explosion of

petroleum, gas tanks

may cause spreading

of fire

• West

• Fire, Building Damage

• North

• Bridge Damage

• South

• Bridge Damage

• East

• Building Damage, Bridge Damage

POSSIBLE

ISOLATION DUE

TO EARTHQUAKE

IMPACTS (West Valley Fault Scenario)

(MMEIRS, 2004)

TSUNAMI SCENARIO M8.3 Earthquake from Manila Trench

Estimated Tsunami

Height in Manila Bay:

• 3.5 meters (mean sea

level)

• 5.5 meters (+ 2m from

tide)

Arrival Time:

• > 1 hour

TSUNAMI HAZARD

GOALS FOR RISK REDUCTION IN

METRO MANILA (MMEIRS, 2004)

• Develop local and national governance and

business system resistant to strong earthquakes

• Improve resiliency of urban structures and

settlements

• Enhance current risk and emergency

management

• Enhance community disaster management

capacities

• Formulation of reconstruction system

• Promotion of research and technology

development

PRIORITY STRATEGIC APPROACH TO

CONTEND WITH STRONG EARTHQUAKE

Focus Concept

1 – Strengthen

Legal

Framework and

Institutional

Capacity for

Disaster

Management

• Enhance Legal Basis and

support

• Strengthen Institutional

Capacity for Mitigation,

Preparedness and Response

as well as Inter-Institutional

Coordination

PRIORITY STRATEGIC APPROACH TO

CONTEND WITH STRONG EARTHQUAKE

Focus Concept

2 – Build

Capacity for

Relief and

Recovery

• Enhance Emergency Health

and Medical Response

System

• Establish Emergency

Transportation System

• Secure sea ports, airports

• Secure water source and

supply

• Secure power and

communication systems

PRIORITY STRATEGIC APPROACH TO

CONTEND WITH STRONG EARTHQUAKE

Focus Concept

3 – Strengthen

Community

Preparedness

for Earthquakes

and Tsunamis

• Enhance self-reliance and

mutual help for efficient risk

management capacity

• Inculcate Disaster Mitigation

Culture among populace

PRIORITY STRATEGIC APPROACH TO

CONTEND WITH STRONG EARTHQUAKE

Focus Concept

4 – Reduce

Seismic

Dangers of

Residential

Structures

• Strengthen Buildings,

Structures

• Promote and Institute Fire

Safety

• Promote and support further

researches on seismic

hazards and better building

technology

PRIORITY STRATEGIC APPROACH TO

CONTEND WITH STRONG EARTHQUAKE

Focus Concept

5 – Enhance

National System

to Become

Resistant to

Impact of

Earthquakes

• Protect stability of

government function

• Ensure continuity of socio-

economic systems

KEY MESSAGES • Metro Manila and surrounding provinces are prone to

extreme natural events, such as strong earthquakes

and tsunamis. • A large earthquake from the West Valley Fault can

significantly affect Metro Manila and vicinity. A large

earthquake from the Manila Trench can generate a

tsunami that can affect the coastal areas of the

metropolis. • Disaster risk reduction and management efforts must

take into account appropriate science-based

scenarios.

• Let us learn from what happened in Nepal. WE ALL

NEED TO ACT NOW.

/PHIVOLCS

@phivolcs.dost

www.phivolcs.dost.gov.ph

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