Hazard and Vulnerability of Moderate Seismicity Regions

Transcription

1 Hazard and Vulnerability of Moderate Seismicity Regions presented by Professor Tso-Chien PAN Dean, College of Engineering Director, 25 October 2010 DRM GDLN Session on Earthquake Vulnerability Reduction

2 Outline Why the focus on Asia General Framework for Seismic Risk Assessment Seismic Hazard Source: Regional Seismicity Site Effects: Soft Soil Amplification of Ground Motions Seismic Vulnerability Exposure: Built Environment Vulnerability: Lightly Reinforced Concrete Joints Summary

3 Why the focus on Asia Historically, Asia has suffered the most due to catastrophic events. Asia has the largest growth of real assets and urban centers on Earth. This has exacerbated the problems of seismic risk management. Climate Change issues will potentially impact Asia more than any other continent.

4 Historical Earthquake Loss ( ) Number of killed Rest of the World, 190,000 Number of affected Rest of the World, 32,000,000 Asia, 126,000,000 Asia, 920,000 Total = 1,110,000 Estimated Damage (USD Million) Rest of the World, 133,000 Total = 158,000,000 Asia, 315,000 Total = 448,000 Source: EM-DAT: The OFDA/CRED International Disaster Database Université Catholique de Louvain Brussels Belgium.

5 Rapid Growth Top 15 Mega-Cities (2009) 1. Tokyo Japan Asia 33,800, Seoul South Korea Asia 23,900, Mexico City Mexico North America 22,900, Delhi India Asia 22,400, Mumbai India Asia 22,300, New York USA North America 21,900, Sao Paulo Brazil South America 21,000, Manila Philippines Asia 19,200, Los Angeles USA North America 18,000, Shanghai China Asia 17,900, Osaka Japan Asia 16,700, Kolkata India Asia 16,000, Karachi Pakistan Asia 15,700, Guangzhou China Asia 15,300, Jakarta Indonesia Asia 15,100,000

6 General Framework for Seismic Risk Assessment EQ Source Modelling Path Directivity Site Soil Rock Building Response Risk Assessment & Loss Estimate: HAZUS, eg Hazards: Peak Ground Acceleration and/or Spectra Vulnerability: Buildings and Infrastructure

7 Framework for Seismic Risk Assessment Dec 2004 Penang Malay Peninsula Eurasian Plate Source: Magnitude 7.8 and 8.8 earthquakes Loss Assessment: Direct and Indirect Losses Latitude ( o ) 3 Sm Ni 0 Bt Pekanbaru 52 mm/yr Padang (N10 o E) Sb 13 Sep :35:26 Sp 12 Sep :49: Mar 2005 & NP SP Palembang 1861 Bengkulu 12 Sep :10:26 Scenario A En mm/yr Jakarta Scenarios B & C Java 60 mm/yr -9 (N17 o E) km Indian-Australian Plate Longitude ( o ) 1797 Medan Sumatra Sumatran Fault 1833 Path Kuala Lumpur Singapore Site Site Effects Exposures: Buildings & Infrastructure

8 The Earth s Crustal Plate

9 Southeast Asia Myanmar Laos Thailand Vietnam Cambodia Philippines Malaysia Brunei Singapore Indonesia

10 Latitude ( o ) Regional Tectonic Setting Sumatra Fault mm/yr (N10 o E) Sumatra Subduction 57 mm/yr Penang Indian-Australian Plate 60 mm/yr (N17 o E) Malay Peninsula Medan Kuala Lumpur km Pekan Baru Sumatra Singapore Palembang Longitude ( o ) Eurasian Plate Java Singapore is located in a stable region on the Eurasian Plate Sumatra subduction (± 650 km away): Shallow dipping Very high seismic potential Sumatra fault (± 450 km away): Right-lateral faulting Total length is 1,900 km Highly segmented

11 Features of Subduction subduction interface Oceanic fracture zone Sumatran fault Obliquity of subduction has led to formation of the Sumatra fault, within the volcanic arc. Splintering of the subducting oceanic plate occurs along faults within the downgoing slab.

12 Epicentres of Sumatra EQs with M 6.5 ( )

13 Padang, Sumatra Earthquake (Mw=6.3) Evacuation at Suntec City Towers and other high-rise buildings in the central business district area

14 Bengkulu-Mentawai Earthquake (Mw=8.4)

15 Bengkulu-Mentawai Earthquake (Mw=8.4,7.9,7.0) Historical and 2007 rupture areas

16 Giant Earthquakes Since 2000 Singapore

17 Kepulauan Mentawai EQ, Indonesia, M=7.5 ( :42:22 UTC)

18 Historical Seismicity Sumatra EQs Felt in Singapore ( )

19 Sumatran EQs Felt in Singapore per Decade As of 22 July 2010 Number of events

20 Singapore s Waterfront Skyline Classic Change in Exposure due to Urbanization What if the 1833 event recurs? Codes for EQ resistant design of buildings for long-distance EQs (circa 1960) (circa 2000)

21 Site Effects - Singapore Surface Geology

22 Buildings Responded to Sumatra Events before Bengkulu EQ

23 Buildings Responded to Bengkulu EQ

24 Development of Public Housing Home to a large % of population

25 Some Structural Systems Slab Block Point Block

26 Seismic Performance of Reinforced Concrete Columns Brittle Ductile

27 Seismic Performance: Beam Wide Column Joints

28 Seismic Performance: Lightly Reinforced Beam-Column Joints

29 Summary Hazard Assessment: Increased Seismic Activities Number of Sumatra events felt in Singapore Coinciding with high construction activities Vulnerability Assessment: Rapid Urbanization Increased number of buildings and taller buildings Site-Dependent Building Response Softer sites are more responsive to distant earthquakes Lightly Reinforced Concrete Beam-Column Joints Responding differently from RC joints designed for buildings in high-seismic regions

30 Thank you! Q&A

31 The 30 Sep 2009 Padang Earthquake Date: 2009/ 9/30 Centroid Time: 10:16:17.4 GMT Lat= Lon= Depth= 75.8 Half duration=14.5 Centroid time minus hypocenter time: 8.4 Moment Tensor: Expo= Mw = 7.5 mb = 7.6 Ms = 7.6 Scalar Moment = 2.64e+27 Fault plane: strike=72 dip=51 slip=136 Fault plane: strike=193 dip=58 slip=49

32 Christchurch, NZ, Earthquake, M=7.1, 4 Sept 2010 Occurred at a location away from the well known Fault Line: Alpine Fault Fault ruptured has remained dormant for 16,000 years. 7.1, 3 rd September 2010

33 Damage of Masonry Components