Tuesday, 2 April 2024, 1950 PDT
The whole island of Taiwan suffered the effects of a Magnitude 7.4 earthquake about three hours ago (0758 local Taiwan time on Wednesday, 3 April). The quake’s epicenter was 18km SSW of Hualien City (eastern Taiwan) at 34km depth. The L.A. Times reports there’s minimal tsunami risk to Guam, Hawaii, and the U.S. west coast. Japan is assessing tsnuami impacts on Okinawa.
earthquake.usgs.gov/… USGS earthquake event page, incl tectonic analysis and aftershock maps
https://www.latimes.com/world-nation/story/2024-04-02/a-strong-earthquake-rocks-entire-island-of-taiwan-collapsing-buildings-tsunami-alert-issued
www.chinatimes.com/… in Mandarin, but has links to many photos and videos
www.nytimes.com/… live updates and in-country comments from readers
wapo.st/… Washington Post gift link, live updates
www.cnbc.com/… CNBC
www.bbc.com/… BBC
www.theguardian.com/… The Guardian
mainichi.jp/… Japanese English language newspaper. Reports 7.7 Magnitude, tsunami warning downgraded.
USGS Tectonic Summary
The April 2, 2024, M 7.4 earthquake on the eastern coast of Taiwan occurred as the result of reverse faulting near the boundary between the Eurasia and Philippine Sea plates. The earthquake was followed by a M 6.5 aftershock 13 minutes later. The M 7.4 earthquake occurred in a zone of tectonic transition from eastward-oriented subduction of the Eurasia plate to westward-oriented subduction of the Philippine Sea plate. Focal mechanism solutions for the earthquake indicate that rupture occurred on a northeast-southwest-striking, moderately dipping, reverse fault. Given the location, depth, and mechanism of the earthquake, it is likely associated with faulting within the Eurasia plate, above the subduction zone interface. At the location of the earthquake, the Philippine Sea plate is moving northwest with respect to the Eurasian plate at a velocity of about 78 mm/yr.
While commonly plotted as points on maps, earthquakes of this size are more appropriately described as slip over a larger fault area. Reverse faulting events of the size of the April 2, 2024, earthquake are typically about 60 by 35 km in size (length x width).
This tectonically complex region has historically produced many other large earthquakes of M 7+. Over the preceding 50 years, six other M7+ earthquakes have occurred within 250 km of the April 2, 2024, earthquake. The largest of these was an 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 59 km east of the April 2, 2024, event. In 1920, a magnitude 8.2 earthquake, potentially associated with the subduction zone interface between the Philippine Sea and Eurasia plates, occurred immediately east of the April 2 earthquake.
