Abstract: Using D-InSAR technology and by processing 7 track 56 scenes ALOS/PALSAR data,the surface deformation field of Wenchuan,Sichuan earthquake on May 12,2008 has been extracted.The deformation field covers a 500km?450km area and crosses Jinchuan-Shimian,Heishui-Leshan,Songpan-Pengshan,Nanping-Jianyang,and Kangxian-Chongqing regions,including the severely earthquake-hit areas,such as Lixian,Wenchuan,Maoxian,Beichuan,Qingchuan,and so on.The results show that the deformation field scope is large and the Sichuan basin has been deformed to different degrees.The incoherent belt near earthquake fault shows that the main earthquake surface rupture zone is on the Beichuan-Yingxiu Fault zone.The trackable surface rupture zone runs from the southwest of Yingxiu near the macroscopic epicenter to the north of Suhe in Qingchuan county,about 230km long.The southwest section of the seismogenic fault from Wenchuan to Maoxian shows an incoherent band width obviously larger than that of other incoherent parts,which is closely related to the surface rupture from Dujiangyan to Anxian on the Pengxian-Guanxian Fault(the Mountain Front Fault),and this surface rupture zone is about 70km long.Away from the seismic fault region,the northwest wall of the fault uplifted and the southeast wall subsided.However,both walls in the vicinity of the seismic fault uplifted locally,and along the fault the distribution is very uneven,showing strong segmentation,which indicates the fault is characterized by reverse thrust.The differences of epicentral positions and earthquake origin time given by Harvard,USGS,NEIC,CENC also show that the Wenchuan earthquake rupture process is a multi-point breakdown process.The largest relative deformation amounting to 260cm occurred in the epicentral region on the west of Yingxiu;if converted into vertical deformation,the relative vertical deformation of the two regions is up to 3.3m.In Ya'an and Emei mountain area,the settlement is about 35cm.In Chongqing and to its south,there is about 25cm small-scale uplift.

Key words: M_S 8.0 Wenchuan earthquake, seismic activity, incoherent region, coseismic deformation survey line

摘要： 采用7条地震前后日本ALOS/PALSAR整轨数据,利用D-InSAR技术提取了2008年5月12日四川汶川地震500km×450km的地表连续同震形变场。形变场覆盖了金川—石棉、黑水—乐山、松盘—彭山、南坪—简阳、康县—重庆所有区域,包括了理县、汶川、茂县、北川、青川等重灾区域。结果显示,整个形变场影响范围较大,四川盆地出现了不同程度的地表形变。发震断层附近的非相干区域显示此次地震地表主破裂带在北川-映秀断裂带上,可以追踪出地表破裂带从汶川县映秀镇西南震中附近一直到青川县苏河北侧,全长约为230km。在发震断层西南段汶川至茂县一带,非相干条带的宽度明显大于其它段落,这与彭县-灌县断裂(前山断裂)的都江堰—安县段地表破裂段密切相关,地表破裂带长约70km。在远离发震断层的区域,西北盘总体表现为抬升,东南盘表现为沉降。但在发震断层附近,断层两侧均表现为局部抬升,且沿断层形变量分布很不均匀,表现出较强的分段性,显示出发震断层以逆冲为主的断层性质。从美国哈佛大学(Harvard)、美国地质调查局(USGS)与美国国家地震信息中心(NEIC)、中国地震台网中心(CENC)所给出的震中位置和发震时刻的差异来看,也反映出汶川地震破裂过程是多点破裂过程。在汶川县映秀镇西侧震中区,最大相对形变量达260cm,如果全部换算成垂直形变,则两个区域的垂直相对形变达3.3m。在雅安、峨眉山一带约有35cm的沉降区,在重庆及其南侧区域约有25cm的小范围隆起。

关键词: 汶川M_S 8.0地震, 地震活动性, 非相干区域, 同震形变场测线