地震波传播模拟动画.ppt

Magnitude 7.7 NORTHERN SUMATRA, INDONESIATuesday, April 6, 2010 at 22:15:02 UTC A major 7.7 earthquake occurred Tuesday 205?km (125?miles) west-northwest of Sibolga, Sumatra, Indonesia. There was widespread panic as residents rushed to higher ground. Local media report that hundreds of houses have been damaged, and there are electricity blackouts across the province. Following the earthquake, people remained out on the streets, wary of aftershocks. USGS Residents sit on a truck as they prepare to flee after an earthquake in Banda Aceh on Sumatra island, Indonesia, Tuesday, April 6, 2010. A 7.7 earthquake shook Indonesias northwest island of Sumatra early Tuesday, prompting a brief tsunami warning and sending residents rushing for higher ground. (AP Photo/Heri Juanda) The red star shows the epicenter of the earthquake while the arrows show the direction of motion of the Australia-Indian Plate. At the location of this earthquake, the Australia-Indian Plate moves north-northeast with respect to the Sunda microplate at a velocity of approximately 60-65 mm/yr. The Sunda trench axis strikes approximately N 37°W. The Indian Ocean crust is moving in an azimuth of ~ N 23°E relative to Southeast Asia, giving an angle of obliquity of 60°. UNAVCO Magnitude 7.7 NORTHERN SUMATRA, INDONESIATuesday, April 6, 2010 at 22:15:02 UTC Sunda microplate (or southeast promontory of EurasianPlate) Australia-Indian Plate Sunda Trench Earthquake Magnitude 7.7 NORTHERN SUMATRA, INDONESIATuesday, April 6, 2010 at 22:15:02 UTC The subduction zone surrounding the immediate region of this event last slipped during the M8.6 earthquake of March 2005, and todays event (red star) appears to have occurred within the rupture zone of that earthquake. Within a few years, almost the entire length of the Sumatra megathrust has ruptured: two M7.3 earthquakes 125 km to the north in 2002 and 2008; a M9.1 earthquake that ruptured to within 125 km north of this earthquake