Earthquake Hazards and Risk Scenario for Metro Manila and Vicinity: the Need for Whole of Society Preparedness

Transcription

1 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

2 What Happened in Nepal?

3 2015 April 25 Nepal Earthquake Time: :11:26 (UTC), Saturday Magnitude: 7.8 Depth: 15 km Nearby Cities 34km (21mi) ESE of Lamjung, Nepal 77km (48mi) NW of Kathmandu, Nepal * LAST MOVEMENT OF FAULT SEGMENT = 1344

4 Magnitude 7.8 NEPAL Saturday, April 25, 2015 at 06:11:26 UTC The Modified Mercalli Intensity (MMI) scale depicts shaking severity. The area nearest Katmandu experienced very strong to severe shaking. Shaking Intensity Modified Mercalli Intensity Perceived Shaking Extreme Violent Severe Very Strong Strong Moderate Light Weak Not Felt Image courtesy of the US Geological Survey USGS Estimated shaking Intensity from M 7.8 Earthquake

5 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. 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 , 2006.

6 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.

7 What is the Earthquake Scenario in Metro Manila and nearby Provinces?

8 LATEST DAMAGING EARTHQUAKE IN METRO MANILA M 7.3 Casiguran, Aurora Earthquake, 02 August 1968 Ruby Tower in Manila collapsed 268 killed, 260 injured

9 EARTHQUAKE GENERATORS IN METRO MANILA AND VICINITY

10 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

11 EARTHQUAKE-RELATED HAZARDS Fault Faulting (Ground) Rupture Ground Shaking Liquefaction Tsunami Fire Landslide

12 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)

13 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)

14 GROUND SHAKING IN GREATER METRO MANILA (West Valley Fault Earthquake) (Risk Analysis Project, 2013: PHIVOLCS, GA supported by AusAID) BULACAN BULACAN NCR RIZAL NCR RIZAL CAVITE CAVITE LAGUNA LAGUNA M7.2 M6.5

15 INTENSITY VIII (VERY DESTRUCTIVE) GROUND SHAKING 1995 Kobe Earthquake

16 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 % Partly % Storey Building Damage Heavy - 11% Partly - 27% 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

17 BUILDING AND CASUALTY ESTIMATES (2) FOR METRO MANILA FROM A WEST VALLEY FAULT EARTHQUAKE 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, ,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 Total Economic Losses (millions of PhP) 2,269,000 1,773,000 Risk Analysis Project, 2013 PHIVOLCS, UP-ICE, GA (AusAID)

18 LIQUEFACTION Dagupan 1990 Subsidence of bridge column Dagupan 1990 Subsidence of building, roads Mindoro 1994 Fissuring of roads La Union, 1990 Damage to buried pipes, tanks

19 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 (READY for GMMA Project, 2013)

20 FIRE AFTER THE EARTHQUAKE M7.2 West Valley Fault Earthquake Navotas Malabon Manila Pasay Paranaque Las Pinas *MMEIRS, 2004 Valenzuela Quezon City Caloocan Makati Marikina Pasig San Juan Mandaluyong Pateros Taguig Muntinlupa Fire outbreak by electrical short circuit; toppling of lamps, candles Explosion of petroleum, gas tanks may cause spreading of fire Maximum Burnt Number 500-1, (MMEIRS, 2004)

21 POSSIBLE ISOLATION DUE TO EARTHQUAKE IMPACTS (West Valley Fault Scenario) West Fire, Building Damage North Bridge Damage South Bridge Damage East Building Damage, Bridge Damage (MMEIRS, 2004)

22 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

23 TSUNAMI HAZARD

24 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

25 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

26 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

27 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

28 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

29 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 socioeconomic systems

30 Let us learn from what happened in Nepal. WE ALL NEED TO ACT NOW. 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.

31 Earthquake & Tsunami (24/7): Tel. Numbers loc 124 / 125 Fax number Volcano (24/7): Tel. Numbers loc 127 Telefax number IEC materials: loc