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Taiwan Earthquake, 9-21-99 - Vilasinee Kongsomboonvech. Earthquake situated in an active seismological region on “ring of fire” North - Philippine plate subducting under Eurasian plate South - Eurasian plate subducting under Philippine plate Taiwan is a collision zone
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Taiwan Earthquake, 9-21-99 - Vilasinee Kongsomboonvech • Earthquake situated in an active seismological region on “ring of fire” • North - Philippine plate subducting under Eurasian plate • South - Eurasian plate subducting under Philippine plate • Taiwan is a collision zone • Plates move about 7cm/year = mts rise 5mm/yr
Geological Background - Taiwan • More active seismically than most of California • ~15,000 EQ occur/yr • 51 faults score the island • Island size 250m x 90m = 9% of California • Taiwan’s population ~22,113,250 = 2/3 of California’s population
Chi-Chi “921” EQ • 9/21/1999 1:47am • 7.6 on the Richter scale • Subduction zone EQ exposed on land • “Unusual” because it was very shallow & usually occur out @ sea • NO PRIOR WARNING! • At least 2,297 killed - 8,700 injured -600,000 homeless
Chi-Chi “921” EQ • Within 30m of focus of main shock, six smaller aftershocks occurred registering @ 6+ on Richter’s scale • Total of 10,000 aftershocks • More powerful than the EQ that occurred in Turkey a month earlier that killed 14,000 people • No relationship - “bad coincidence”
Chi-Chi “921” EQ • Most damage to rural areas • Older units collapsed b/c not constructed to be EQ proof – some newer units collapsed due to corrupt use of $$$ • For a demo of EQ resistant building construction vs. non-resistant see:http://news.bbc.co.uk/olmedia/450000/images/_454259_earthquake_300.gif