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

Images of “921”

Images of “921”