Wang Qiuliang

Seismic hazard assessment of the Three Gorges Project

Abstract: Seismic monitoring data for the past 50 years in the Three Gorges Reservoir area show that the reservoir head area is a typical weak seismic region with low seismicity before impoundment and that the epicenters were concentrated in the east and west sides of the Zigui Basin, most of which were natural tectonic earthquakes. After impoundment, the seismic activity shifted to the segment between Badong and Zigui along the Yangtze River, mainly within 5 km of the reservoir bank. The seismogenesis was categorized into four types; Karst collapse earthquakes, earthquakes caused by Karst gas explosion, mining tunnel collapse earthquakes, and rock (terrane) slip earthquakes, all of which are related to the lithology, structure, and tectonics of near-surface geological bodies of the area. Compared with the seismicity before impoundment, the seismic frequency increase was remarkable, with most of the magnitudes below M s2. 0. Therefore, the intensity of the earthquakes remained at a low level. On November 22, 2008, a magnitude 4. 1 earthquake, the largest earthquake recorded since impoundment, occurred in Quyuan Town, Zigui County. The intensity and PGA of reservoir-induced earthquakes are higher than those of tectonic earthquakes with equal magnitude, but the peak intensity of reservoir-induced earthquakes is not likely to go beyond that of the estimated range from earlier studies.

Source rupture process inversion of the 2013 Lushan earthquake, China

Abstract: The spatial and temporal slip distribution of the Lushan earthquake was estimated using teleseismic body wave data. To perform a stable inversion, we applied smoothing constraints and determined their optimal relative weights on the observed data using an optimized Akaike’s Bayesian Information Criterion (ABIC). The inversion generated the source parameters. Strike, dip and slip were 218°, 39° and 100. 8°, respectively. A seismic moment ( M 0 ) was 2. 1 × 10 20 Nm with a moment magnitude ( M w) of 6. 8, and a source duration was approximately 30 second. The rupture propagated along the dip direction, and the maximum slip occurred at the hypocenter. The maximum slip was approximately 2. 1 m, although this earthquake did not cause an apparent surface rupture. The energy was mainly released within 10 second. In addition, the Lushan earthquake was apparently related to the 2008 Wenchuan earthquake. However, the question of whether it was an aftershock of the Wenchuan earthquake requires further study.

Factor analysis of earthquake-induced geological disasters of the M7. 0 Lushan earthquake in China

Abstract: The seismic intensities, lithologic characteristics and terrain features from a 3000 km 2 -region near the epicenter of the Lushan earthquake are used to analyze earthquake-induced geological disaster. The preliminary results indicate that secondary effects of the earthquake will affect specific areas, including those with glutenite and carbonate bedrock, a seismic intensity of IX, slopes between 40° and 50°, elevations of less than 2500 m, slope change rates between 20° and 30°, slope curvatures from –1 to –0. 5 and 0. 5 to 1, and relief between 50 and 100 m. Regions with susceptibility indices greater than 0. 71 are prone to landslides and collapses. The secondary features are mainly distributed on both sides of the ridges that extend from Baosheng to Shuangshi and from Baosheng to Longxing. Other features are scattered on both sides of the ridges that extend from Qishuping to Baosheng and from Masangping to Lingguan. The distribution of the earthquake-related features trends in the NE direction, and the area that was most affected by the Lushan earthquake covers approximately 52.4 km 2 .

Correlation between seismicity and geomorphology in Dingxi Basin, Gansu Province, China

Abstract: A M 6.6 earthquake occurred on July 22, 2013 at Dingxi Basin in Gansu Province within the tectonially expanding northeastern margin of the Qinghai-Tibet Plateau. We analyzed the geomorphological features of the Dingxi Basin by using remote sensing technology and compared them with local seismic activity. We found that most of the river basins are at the robust stage of development and that the major local rivers and the development of some basins boundaries are controlled by the seismic faults. Among four zones identified to have significant tectonic activities, the northwestly-oriented one located in the south has the highest seismic activity, and it is where the M 6. 6 earthquake occurrred.

Building damages in Deyang city by the 2008 Wenchuan earthquake

Abstract: The Ms8.0 Wenchuan earthquake in 2008 caused huge casualties, economic losses, and building damages, which are analyzed. The results show that damages of houses designed according to the current seismic code were significantly smaller than those without such design, suggesting that the code has achieved the desired goal of seismic fortification. Buildings of different kinds of structures showed large differences in damages : Houses with steel-frames and shear walls or steel structures suffered the least damages: those with frames or with brick-and-concrete structures suffered more; old cottages, the most.