Transcript earthquakes
LESSONS LEARNED FROM PAST NOTABLE DISASTERS. TAIWAN PART I: EARTHQUAKES Walter Hays, Global Alliance for Disaster Reduction, Vienna, Virginia, USA NATURAL HAZARDS THAT PLACE TAIWAN’S COMMUNITIES AT RISK EARTHQUAKES GOAL: DISASTER RESILIENCE ENACT AND IMPLEMENT POLICIES HAVING HIGH BENEFIT/COST FOR COMMUNITY RESILIENCE TYPHOONS FLOODS LANDSLIDES ENVIRONMENTAL DEGRADATION GLOBAL CLIMATE CHANGE EARTHQUAKES EARTHQUAKES OCCUR FREQUENTLY IN TAIWAN AS A RESULT OF COMPLEX INTERACTIONS OF THE PHILIPPINE AND EURASIAN PLATES JI JI, TAIWAN EARTHQUAKE OCCURRENCE M 7.3 Shallow depth (about 2 km) 1:47 am SEPTEMBER 21, 1999 • This earthquake was a subduction zone earthquake caused by interaction of the Philippine plate with the Eurasian plate. THE CAUSATIVE FAULT • The quake was generated by slip on the Chelongpu fault. • The regional compression caused thrust faulting. • Over 60 km of surface faulting with lateral and vertical displacements reaching 9 m and 5 m, respectively, occurred in the center of the Island. EARTHQUAKE RISK •QUAKE HAZARDS •BLDG. INVENTORY •VULNERABILITY •LOCATION DATA BASES AND INFORMATION ACCEPTABLE RISK RISK UNACCEPTABLE RISK TAIWAN’S GOAL: EARTHQUAKE DISASTER RESILIENCE COMMUNITIES POLICY OPTIONS HAZARDS: GROUND SHAKING GROUND FAILURE SURFACE FAULTING TECTONIC DEFORMATION TSUNAMI RUN UP AFTERSHOCKS • PREPAREDNESS •PROTECTION •EARLY WARNING •EMERGENCY RESPONSE •RECOVERY and RECONSTRUCTION CAUSES OF DAMAGE INADEQUATE RESISTANCE TO HORIZONTAL GROUND SHAKING SOIL AMPLIFICATION PERMANENT DISPLACEMENT (SURFACE FAULTING & GROUND FAILURE) EARTHQUAKES “DISASTER LABORATORIES” IRREGULARITIES IN ELEVATION AND PLAN TSUNAMI WAVE RUNUP POOR DETAILING AND WEAK CONSTRUCTION MATERIALS FRAGILITY OF NON-STRUCTURAL ELEMENTS TOWARDS EARTHQUAKE DISASTER RESILIENCE RISK ASSESSMENT • VULNERABILITY • COST • EXPOSURE QUAKES • EVENT EXPECTED LOSS • BENEFIT •CONSEQUENCES POLICY ASSESSMENT POLICY ADOPTION LESSONS LEARNED FOR DISASTER RESILIENCE • ALL NOTABLE EARTHQUAKES • PREPAREDNESS PLANNING FOR THE INEVITABLE GROUND SHAKING IS ESSENTIAL FOR COMMUNITY RESILIENCE. PHYSICAL EFFECTS: GROUND SHAKING • Strong motion records showed that ground shaking was characterized by long-period energy related to the magnitude and local site conditions. • It was several times greater than the level prescribed in the building code. LESSONS LEARNED FOR DISASTER RESILIENCE • ALL NOTABLE EARTHQUAKES • PROTECTION OF BUILDINGS AND INFRASTRUCTURE IS ESSENTIAL FOR COMMUNITY RESILIENCE. BUILDING IMPACTS • 44,338 buildings collapsed, and an additional 41,336 houses and buildings were severely damaged. • Twenty 10- to 20-story residential buildings either collapsed or experienced significant damage, suggesting frequency-dependent site amplification. • Strong ground shaking from the main shock and its large aftershocks caused the collapse of mid-rise buildings in Taipei, the capitol, which is located about 140 km north of the epicenter in a deep alluvial basin. • Strong ground shaking, ground failure, and surface fault rupture caused power outages and severe damage to lifelines. • Some kinds of lifeline damage had NEVER been observed in previous earthquakes. • The loss of power had wide ranging effects, including disruption of Taiwan’s semiconductor fabrication facilities. • A 30-km-long surface fault rupture caused major destruction to schools, residences, dams, embankments and bridges located in or near the rupture zone. • Most of the bridges that suffered significant damage were located in the area bounded by two thrust faults that ruptured the surface. • Liquefaction caused damage in a residential neighborhood of Yuanlin located in Changhua County. •Extensive liquefaction-induced damage was also observed in parts of Taichung Harbor. LESSONS LEARNED FOR DISASTER RESILIENCE • ALL NATURAL HAZARDS • CAPACITY FOR INTELLIGENT EMERGENCY RESPONSE IS ESSENTIAL FOR COMMUNITY RESILIENCE. LESSONS LEARNED FOR DISASTER RESILIENCE • ALL NATURAL HAZARDS • CAPACITY FOR RECOVERY AND RECONSTRUCTION IS ESSENTIAL FOR COMMUNITY RESILIENCE. IMPACTS • The death toll reached 2,416. •11,446 were injured. • Economic losses reached $9.2 billion. • Short-term global stock market prices were influenced by impacts on the semi-conductor industry. BASED ON REPORTS BY USGS, EERI, ASCE/TCLEE, MCEER, TAIWAN AGENCIES, AND OTHERS