对2004年苏门答腊-安达曼岛地震的测地学机制讨论  

Discussions on Possible Geodetic Mechanism for the 2004 Sumatra-Andaman Islands Earthquake

作　　者：杨志根[1] 

机构地区：[1]中国科学院上海天文台

出　　处：《天文学进展》2007年第3期270-278,共9页Progress In Astronomy

基　　金：中国科学院动力大地测量重点实验室创新课题

摘　　要：采用GPS测地学观测资料,基于NUVEL-1A板块运动模型,分别估计和讨论了INDI板块与Burma微板块之间、AUST板块与Burma/SE EURA板块之间的聚敛率,以及INDI与AUST板块间的相对速率。结果显示,沿苏门答腊-尼科巴群岛和沿安达曼群岛两个阶段的地壳破裂分别与AUST板块和Burma板块间、INDI板块和Burma板块间的聚敛率密切相关,从板块运动学角度提供了解释整个苏门答腊-安达曼群岛地壳破裂带上板块间耦合由南向北递减观测结论的佐证;在NUVEL-1A板块运动模型的背景下,2004年苏门答腊-安达曼岛主震应当为AUST板块相对于Burma/SE EURA板块以近60 mm/a,方向NE 30°～35°的运动所致,而非INDI板块或印-澳(INDI-AUST)板块运动所致;根据2004年苏门答腊-安达曼岛地壳破裂特征并结合其余震的分布,进一步肯定了AUST板块西北边界带的地质位置分布。　The 2004 Sumatra-Andaman earthquake with moment magnitude 9.3 on December 26,2004 was the second largest earthquake in the instrumental record and the first giant earthquake to have occurred since the advent of modern space geodesy.In this work,we report estimates and results by using GPS measurements and basing on the boundary distributions of the Indian plate and Australia plates in NUVEL-1A plate motion model,the convergence rates between Indian and Burma plates and between Australian and Burma plates,as welt as the relative motion between Indian and Australian plates are respectively estimated.Results indicate that the two phases of ruptures that occurred along respectively the Sumatra-Nicobar Islands and the Andaman Islands in Indian Ocean were probably related with triggering of different plate interactions.The reduction between megathrust coupling as a function of distance northward from epicenter can be kinematically interpreted by distribution of the estimated convergence rates, The 2004 Sumatra-Anda.man main-shock should be induced by the Australia plate motion,which is towards NE33°-35°with a velocity of about.60 mm/a relative to Burma/southeast Eurasian plate.The geological distribution of the northwestern most part of the AUST plate in NUVEL-1A may be further confirmed by this earthquake.

关 键 词：空间大地测量 地震 NUVEL-1A板块运动模型 GPS 板块间聚敛率 地壳破裂的测地学机制 

分 类 号：P315.1[天文地球—地震学] P541[天文地球—固体地球物理学]