M 7.1 - 67 km ENE of Hualien City, Taiwan
- 2002-03-31 06:52:50 (UTC)
- 24.279°N 122.179°E
- 32.8 km depth
Interactive Map Regional Information Felt Report - Tell Us! 000000Responses Contribute to citizen science. Please tell us about your experience.
- ShakeMap
VImmi 
Estimated Intensity Map Origin - Review Status
- REVIEWED
- Magnitude
- 7.1 mwc
- Depth
- 32.8 km
- Time
- 2002-03-31 06:52:50 UTC
Moment Tensor Fault Plane Solution View Nearby Seismicity - Time Range
± Three Weeks - Search Radius
250.0 km - Magnitude Range
≥ 4.0
Contributors US
USGS National Earthquake Information Center, PDE
Tectonic Summary
The March 31, 2002, M 7.1 earthquake off the northeastern coast of Taiwan occurred as the result of shallow reverse faulting in a zone of transition along the boundary between the Eurasia plate and the Philippine Sea plate, at the most southwestern end of the Ryukyu subduction zone, and where subduction-dominated tectonics to the northeast progressively evolve towards more collision-dominated convergence in Taiwan. Focal mechanism solutions for the earthquake indicate that rupture occurred on an east-west-striking, moderately dipping, reverse fault. At the location of the earthquake, the Philippine Sea plate is moving northwest with respect to the Eurasia plate at a velocity of about 78 mm/yr.
In Taiwan, the type of lithosphere local to the plate boundary determines how the two major plates interact; oceanic lithosphere in the south causes the denser Eurasia plate to subduct beneath the Philippine Sea plate, while the buoyant continental lithosphere in the north resists subduction and a significant fraction of plate convergence is accommodated by intense compressional deformation of the Earth’s crust. To the east of Taiwan, seismicity is predominantly associated with the northward subduction of the Philippine Sea plate beneath Eurasia; the location, depth, and focal mechanism solutions for the March 31st earthquake are consistent with its occurrence on this subduction thrust interface.
This tectonically complex region has historically produced many other large earthquakes of M 7+. Over the preceding 40 years, the 200-km area surrounding the March 31st earthquake has experienced nine such events. The most recent was also the largest—a M 7.7 earthquake in September 1999 (the Chi-Chi earthquake) that resulted in at least 2,297 fatalities, caused damage estimated at $14 billion, and occurred on land 150 km southwest of the March 31st event.
Hayes et al. (2016) Tectonic summaries of magnitude 7 and greater earthquakes from 2000 to 2015, USGS Open-File Report 2016-1192. (5.2 MB PDF)
Summary Poster
