Collaborative Research: Deformation Processes in the Central Andaman Islands

合作研究：安达曼群岛中部的变形过程

• 批准号: 0537629
• 负责人: John Puchakayala
• 金额: --
• 依托单位: University of Memphis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-02-01 至 2009-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0537629&HistoricalAwards=false
• 关键词: Collaborative; Research; Deformation; Processes; Central

The Mw=9.3 Dec 2004 Sumatra earthquake ruptured 1000 miles of India's eastern plate boundary causing damage in the Nicobar and Andaman islands, shifting them bodily 3m-7m southwestward, and tilting them down to the east. Although shaking damage in the Andaman and Nicobar islands was minor, the tilting caused massive damage to coastline ecologies. Thousands of hectares of agricultural land were flooded, and erosion of forested shorelines has commenced in regions that sank. Hundreds of km of coral reefs were killed where the land rose, with attendant loss of nearshore fishing grounds. Yet clearly this was not the first time that this has occurred, and it is certain that it will occur again.Several societal questions arise. How frequently do these catastrophic tsunami earthquakes occur? Are the flooded islands permanently drowned or will they slowly recover their former levels? Will the saline intrusion and flooding of shoreline farmland be reversed or worsened in the coming decades. Will harbor defenses and docks require extended construction to accommodate additional submergence or emergence. In what way does the Sumatra earthquake resemble a similar Mw=9 expected in the Pacific NW of the US? What can be learned from the Sumatra earthquake that has application to the coasts of Oregon and Washington?These questions can be answered from a geophysical knowledge of the subsurface process involved in the Sumatra/Andaman event. Near Port Blair, where most of the people of the Andaman/Nicobar islands live, the plate boundary accomodates both northward motion of India and the westward motion of the Andaman plate: every 100 years it accommodate s roughly1 m of northward motion and 4 m of convergence. All this motion occurs infrequently in earthquakes, yet it is driven by slow interseismic processes.Scientists from Memphis and Colorado are investigating continued movements in the Andaman islands using Global Positioning geodesy and sea level monitoring devices to find out whether these catastrophic changes are increasing or decreasing. The spatial variation of these effects with time provides unique constraints on the continuing processes in the islands. Their initial results indicate that although the islands continue to move SW some of the subsidence has been reversed. In this two year project they hope to provide many hundreds of points to constrain future motions, and to answer how frequently these earthquakes occur.One of their objectives is to show local scientists how to undertake these kinds of measurements. Strong collaborative agreements have been established with scientists affiliated with the Society for Andaman and Nicobar Ecology (SANE) who have access throughout most of the islands.

2004年12月发生的里氏9.3级苏门答腊地震使印度东部板块边界断裂了1000英里，尼科巴群岛和安达曼群岛受到破坏，向西南方向移动了3米至7米，并向东倾斜。虽然震动对安达曼和尼科巴群岛造成的破坏较小，但倾斜对海岸线生态造成了巨大破坏。数千公顷的农田被淹没，在沉没的地区，森林海岸线已经开始受到侵蚀。数百公里的珊瑚礁在海平面上升的地方被杀死，随之而来的是近岸渔场的损失。然而，这种情况显然不是第一次发生，而且肯定还会再次发生。由此产生了几个社会问题。这些灾难性的海啸地震多久发生一次？被洪水淹没的岛屿是会被永久淹没，还是会慢慢恢复到原来的水平？在未来的几十年里，盐碱地的入侵和海岸线农田的洪水是否会被逆转或恶化？港口防御和码头需要扩展建设，以适应额外的水下或紧急情况。苏门答腊地震在哪些方面与美国西北太平洋预计发生的Mw=9级地震相似？我们可以从苏门答腊地震中学到什么，它适用于俄勒冈州和华盛顿州的海岸？这些问题可以从苏门答腊/安达曼事件中涉及的地下过程的地球物理知识中得到回答。在安达曼/尼科巴群岛大多数居民居住的布莱尔港附近，板块边界容纳了印度板块的向北运动和安达曼板块的向西运动：每100年它容纳大约1米的向北运动和4米的辐合。所有这些运动在地震中很少发生，但它是由缓慢的地震间过程驱动的。来自孟菲斯和科罗拉多的科学家正在使用全球定位测量仪和海平面监测设备调查安达曼群岛的持续移动，以找出这些灾难性变化是在增加还是减少。这些影响随时间的空间变化对岛屿上的持续过程提供了独特的限制。他们的初步结果表明，尽管这些岛屿继续向西南移动，但一些下沉已经逆转。在这个为期两年的项目中，他们希望提供数百个点来约束未来的运动，并回答这些地震发生的频率。他们的目标之一是向当地科学家展示如何进行这类测量。与隶属于安达曼和尼科巴生态学会（SANE）的科学家建立了强有力的合作协议，他们可以进入大多数岛屿。