Geological info for China Earthquake
May 18, 2008 by tifftai
In class, we’ve talked a little bit about the devastating earthquake in China. Looking at the map, there isn’t any obvious plate boundary near the epicenter. What caused the earthquake?
Here’s the summary from the USGS:
“The Sichuan earthquake of May 12, 2008, occurred as the result of motion on a northeast striking reverse fault or thrust fault on the northwestern margin of the Sichuan Basin. The earthquake’s epicenter and focal-mechanism are consistent with it having occurred as the result of movement on the Longmenshan fault or a tectonically related fault. The earthquake reflects tectonic stresses resulting from the convergence of crustal material slowly moving from the high Tibetan Plateau, to the west, against strong crust underlying the Sichuan Basin and southeastern China.
On a continental scale, the seismicity of central and eastern Asia is a result of northward convergence of the India plate against the Eurasia plate with a velocity of about 50 mm/y. The convergence of the two plates is broadly accommodated by the uplift of the Asian highlands and by the motion of crustal material to the east away from the uplifted Tibetan Plateau.”
So there is folks….a reverse fault resulting from the compression of rocks due to the movement of the India plate against the Eurasia plate!
*Why was this such a strong earthquake?*
(Leave an answer for me.) Use your knowledge from the Geology unit and check out the USGS site.
It was a convergent boundary, and earthquakes that occur because of plates moving toward each other tend to be strong and deep.
PS I saw the USGS site when I was looking for information on the earthquake before I looked at your post. Was this the same website we used in class?