MCEER/NCEER Response: The 921 Taiwan Earthquake

Abstract: In the early morning hours of September 21, 1999, a devastating earthquake struck the central region of Taiwan. This earthquake became known as the 921 earthquake or the “Ji-Ji” or “Chi-Chi” earthquake. The magnitude of the 921 earthquake was MS= 7.6 (Richter scale) or ML= 7.3 (the system used in Taiwan). There were 10 aftershocks greater than magnitude 6. Of these, an ML= 6.8 occurred about 30 hours and 120 hours after the main shock, respectively. An ML= 5.3 aftershock was recorded as long as 260 hours later causing collapses of already damaged structures. As of October 8, the death toll stands at more than 2,350. Over 8,700 people were injured, and dozens remain missing. Approximately 10,000 buildings/homes collapsed and over 7,000 more were damaged.