印、澳板块边界分布与GPS资料用于对2004年Sumatra-Andaman岛地壳破裂测地学机制的再讨论

DIFFERENT BOUNDARY DISTRIBUTION BETWEEN INDIAN AND AUSTRALIA PLATES AND RE-DISCUSSION ON GEODETIC FORMATION OF 2004 SUMATRA-ANDAMAN RUPTURES BY GPS MEASUREMENTS

基于作者此前对印度尼西亚苏门答腊-安达曼岛地震测地学机制的讨论,进一步根据McClos- key等人应用的INDI板块与AUST板块之间大致呈SW(≈S5)～NE(≈N2)走向的板块边界划分模型,利用GPS站速度资料,估计了沿整个苏门答腊-尼科巴岛地壳破裂带INDI板块与Burma/ SE EURA板块之间的板块聚敛率,并与基于NUVEL-1A模型的INDI、AUST板块边界的分布所估计的AUST板块与Burma/SE EURA板块间聚敛率结果作了比较;根据2004年印尼苏门答腊-安达曼岛地壳破裂特征,对该地壳破裂的测地学机制作了进一步讨论,认为基于NUVEL-1A模型的IN- DI、AUST板块边界分布条件下地壳破裂的测地学机制讨论和2004年主震由AUST板块运动触发的结论可能更符合2004年地壳破裂事件的观测结论。目前的Burma微板块的欧拉旋转参数可能不适合用于对该次地壳破裂事件的测地学估计和机制的讨论;INDI、AUST板块间的相对运动是这两者板块间造山带的主要动力源。

With reference to the former discussion on geodetic evidences of formation of the Sumatra-Andaman main-shock and ruptures occurred on 26 December 2004, we further estimate the convergence rates between Indian and Burma/SE Eurasian plates along the Sumatra-Nicobar rupture zone based on the boundary distribution mode between Indian and Australia plates with a tendency of SW （≈S5°） - NE（≈ N2°） , which was used as a reference by many authors in the previous discussions on the 2004 earthquake event. Comparison is made between the estimated rates mentioned above and the corresponding rates between Australian and Burma/SE Eurasian plates based on boundary distributions of the Indian and Australian plates in NUVEL-1A plate motion model. The possible geodetic mechanism for the 2004 Sumatra- Andaman earthquake is confirmed. It is found that the Burma micro-plate would be inadequate to be used to estimate convergence rate between Indian and Burma/SE Eurasian plates because the present parameters of the Burma plate are not expected to be accurate. The relative motion between Indian and Australia plates with （20.8 ±5.3） mm/a would potentially play key role on the interpolate orogens formation.