Preliminary Report on the 22 November 2014Mw 6.1/Ms 6.3 Kangding Earthquake, Western Sichuan, China

Abstract

Online Material: Relocated aftershock catalog figures of moment rate function, magnitude–time distribution, observed strong-motion accelerograms, spectral accelerations versus period, and photos of damaged buildings. The M s 6.3 ( M w 6.1) Kangding earthquake struck western Sichuan Province on 22 November at 08:55:27 UTC (16:55:27 p.m. local time). Its epicenter was located approximately 37 km northwest of Kangding country and 236 km southwest of Chengdu city. The China Earthquake Networks Center (CENC) reported that the epicenter was located at 30.3° N, 101.7° E with a hypocentral depth of 18 km (Fig. 1). Three days after the first shock, another moderate earthquake ( M s 5.8/ M w 5.7) hit the area to the southeast. The distance between the two events is about 10 km. Detailed information of this earthquake is available on the website of China Earthquake Administration (CEA) (http://www.cea.gov.cn/publish/dizhenj/468/553/101420/index.html; last accessed December 2014, in Chinese) and on the website of U.S. Geological Survey (http://earthquake.usgs.gov/earthquakes/eventpage/usb000syy0; last accessed December 2014). The Kangding earthquake was located near the left-lateral, strike-slip Xianshuihe fault system (Allen et al. , 1991). The mainshock was characterized by a strike-slip mechanism, with two nearly vertical nodal planes striking approximately north-northwest and northeast-east, respectively. The maximum intensity was VIII on the Chinese intensity scale (http://en.wikipedia.org/wiki/China\_Seismic\_Intensity_Scale; last accessed December 2014), with the areas above intensity VI being 11,060 km2. The earthquake caused 5 deaths and 80 injuries. The direct economic loss has been estimated as more than 4.2 billion Renminbi (RMB; or about $0.7 billion U.S.). Figure 1. Tectonic blocks and strong earthquakes since 1997 in the Tibetan plateau. Dashed rectangle indicates the region in Figure 2. Large red arrow indicates the crustal motion direction. Black-and-white circles are the focal mechanism of recent strong earthquakes with magnitude larger than M s 7.0. Red-and-white circles are the focal mechanism of the M s 6.3 and 5.8 Kangding …