汶川8.0级地震地表破裂带宽度调查

INVESTIGATION ON WIDTHS OF SURFACE RUPTURE ZONES OF THE M 8.0 WENCHUAN EARTHQUAKE,SICHUAN PROVINCE,CHINA

根据汶川8.0级地震地表破裂带的实地调查,龙门山断裂带的中央断裂与前山断裂地表破裂带宽度自北向南一般<40m。在Ⅹ—Ⅺ度极震区,沿断裂延伸方向破裂带之上及其两侧,各类房屋建筑无论何种结构均绝大部分倒塌损毁。考虑到逆断层作用引起的"地壳缩短"以及各种不确定性,并结合以往历史强震地表破裂带的宽度统计,提出汶川8.0级地震灾后重建时,极震区地震断层两侧的"避让带"宽度为25m。在"避让带"之内,只能建造高于抗震设防标准的2层以下的建筑物,应明确禁止兴建学校、医院等公共建筑。

The 12 May 2008 Wenchuan Earthquake created about 240kin-long surface fault ruptures along the Central Fault and about 72km along the Mountain Front Fault, two of the three sub-parallel secondary faults of Longmenshan thrust faults striking NE-SW,according to field investigation of surface faulting. From north to south,most of the widths of intense surface rupture zones are less than 40m, and above 1/2 are between 10 -30m. Many buildings along fault surface ruptures were destroyed,ineluding those with frame structure or reinforced concrete structure, and we also find some houses or buildings have withstood the strong earthquake and its aftershocks for their excellent performance of earthquake-resistance. The distance between fault scarps and the buildings are from 10 to 30 meters. Based on the field investigation, on the widths of surface rupture zones of historical strong earthquakes, and considering ＂crustal shortening＂ for inverse faulting and other various uncertainties, it is suggested that safety distance away from active fault in rebuilding is 25m. Within this distance, only one or two-storeyed buildings with higher standard of earthquake-resistance can be constructed, and public buildings, like schools and hospitals should be prohibited to build.