Seismic intensity around the epicentral area of the 2008 Wenchuan, Sichuan Province of China earthquake is estimated using a questionnaire survey conducted one month after the earthquake. The survey results show that the seismic intensity of Chengdu city is about VII, Beichuan County and Pengzhou Longmenshan Town about X, and Dujiangyan City about IX in MMI scale, above all are basically in agreement with the survey results of Chinese Earthquake Administration (CEA). The analysis results show that there are two subjective factors affecting the survey results of seismic intensity: one is the sexuality and the other is age. The seismic intensity value by survey of men is often lower than the women's. When the surveyed people is elder than 60 years or younger than 19 years, the seismic intensity value by surveyed those people usually is higher than the others'. In general, the questionnaire survey is a good method to estimate the seismic intensity near to the populated area, but it is unsuitable in an unpopulated area.
A severe earthquake (30.986°N, 103.364°E, Depth=14km), which measured 8.0 Ms, 8.3 Mw, according to Chinese Earthquake Administration (CEA), occurred at 14:28:01.42 CST (06:28:01.42 UTC) on 12 May 2008, in Wenchuan County, southwestern of China. It is also known as the Wenchuan earthquake, after the earthquake's epicenter in Wenchuan County, Sichuan Province. The length of ruptured fault, Longmenshan northeast extension fault, is more than 300 km. The earthquake was so strongly that it can be felt in most part of China, 69,197 people were killed and 18,341people were missing in this earthquake. In addition to such devastating human loss, countless buildings were collapsed or heavy damaged, most of the lifeline suffered heavy damage and heavy geological disaster caused around the ruptured fault, the local economy was suffered fatal destroyed, and the direct economic loss of this earthquake is 845.1 billion RMB (It is about 122.5 billion dollars). It is the deadliest and strongest earthquake to hit China since the 1976 Tangshan earthquake, which killed at least 240,000 people.
Many engineered as well as non-engineered structures were severely damaged and even collapsed during the earthquake. In Beichuan County and Penzhou Longmenshan Town, Un-reinforced masonry (URM) structures and wooden structures were commonly collapsed because of poor construction of their bearing walls, and most of buildings were suffered heavy damage (Plate 1. to Plate 3.). In Dujianyan City and Chengdu City the buildings were suffered different extent damage. For example, in Chengdu City, a few buildings appeared cracks, whereas, in Dujiangyan City, most buildings appeared cracks, some heavy damaged or even collapsed (Plate 2.), and the damaged degree depending on the distance from the ruptured fault.
Most of the destroyed villages were subjected to very intense earthquake motion without attenuation because they were very near the ruptured fault. The site effects amplified the earthquake motion in some areas, causing excessive damage. In general, village near the epicenter and ruptured fault suffered greater damage.
