Geologic evidence for two pre-2004 earthquakes during the last 400-2,000 years near Port Blair
Geologic evidence for two pre-2004 earthquakes during the last 400-2,000 years near Port Blair
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布莱尔港附近过去 400-2,000 年间 2004 年之前两次地震的地质证据
DOI：
10.1130/g31707.1
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
and O. Dikshit
中科院分区：
文献类型：
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作者：
Malik;J.N.;M. Shishikura T. Echigo;Y. Ikeda;K. Satake;H. Kayanne;Y. Sawai;C. V. R. Murty;and O. Dikshit
安达曼群岛布莱尔港附近的海岸地层，在公元2004年苏门答腊-安达曼地震伴随着0.11米的沉降，提供了两个以前的地震，也许都是从过去的400年的证据。其中第一个（事件I）的特点是一个突然的泥上泥炭接触最好的解释沉降类似于2004年。事件II的证据是，上覆的混乱层由桑迪基质中的泥碎屑组成，与补给岩脉相连。这些泥碎屑，可能是由液化产生的，被我们归因于事件II海啸的层压砂和泥覆盖。泥炭中植物遗骸的放射性碳年龄在公元前100年至公元1950年之间。事件I可能类似于2004年苏门答腊-安达曼地震，因为它伴随着下沉（多达1米），但在布莱尔港附近没有强烈的震动。如果第二次事件是公元1762年的阿拉干地震，那么叠层的沙子和泥浆提供了第一个证据，证明这次地震与海啸有关。
Coastal stratigraphy near Port Blair, Andaman Islands, where the A.D. 2004 Sumatra-Andaman earthquake was accompanied by ∼1 m of subsidence, provides evidence for two prior earthquakes, perhaps both from the past 400 yr. The first of these (event I) is marked by an abrupt mud-over-peat contact best explained by subsidence similar to that in 2004. Event II is evidenced by an overlying chaotic layer composed of mud clasts in a sandy matrix that is connected with feeder dikes. These mud clasts, probably produced by liquefaction, are capped by laminated sand and mud that we ascribe to an event II tsunami. Radiocarbon ages of plant remains in the peat give discordant ages in the range 100 B.C. to A.D. 1950. Event I probably resembled the 2004 Sumatra-Andaman earthquake in that it was accompanied by subsidence (as much as 1 m) but not by strong shaking near Port Blair. If event II was the A.D. 1762 Arakan earthquake, the laminated sand and mud provide the first evidence that this earthquake was associated with a tsunami.