Source parameters of the great Sumatran megathrust earthquakes of 1797 and 1833 inferred from coral microatolls
Source parameters of the great Sumatran megathrust earthquakes of 1797 and 1833 inferred from coral microatolls
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根据珊瑚微环礁推断的 1797 年和 1833 年苏门答腊巨型逆冲断层大地震的震源参数
DOI：
10.1029/2005jb004025
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发表时间：
2006
影响因子：
--
通讯作者：
S. Ward
中科院分区：
文献类型：
--
作者：
D. Natawidjaja;K. Sieh;M. Chlieh;J. Galetzka;B. Suwargadi;Hai Cheng;R. Edwards;J. Avouac;S. Ward
根据每年带状珊瑚头记录的相对海平面变化来判断，在1797年和1833年的历史大地震期间，苏门答腊外弧岛在南纬0.5°至3.3°之间发生了巨大的隆起和倾斜。这两次地震的珊瑚数据最完整的是沿着160公里长的明打威群岛，位于南纬3.2°和2°之间。在1797年和1833年，乌斯怀亚的降雨量分别为0.8米和2.8米。1797年的乌斯季延伸了370公里，位于南纬3.2°至0.5°之间。隆升的模式和幅度意味着巨大的逆冲断层破裂对应于8.5至8.7的力矩幅度（M_w）。1833年的隆起区域从南纬2°到至少3.2°不等，根据地震和海啸的历史报告判断，可能高达南纬5°。1833年的隆起和倾斜的模式和幅度与2005年尼亚斯-西默勒巨型逆冲断层地震期间更北地区（北纬0.5° ~ 3°）的隆起和倾斜相似;外弧群岛上升了3米，并向大陆倾斜。珊瑚数据的弹性位错正演模拟产生的巨型逆冲断层破裂的力矩幅度从8.6到8.9不等。在沿着大陆西海岸纬度1°S的巴塘，稀疏的帐户意味着海啸在1797年至少有5米，在1833年至少有3-4米。根据珊瑚隆起的模式模拟的海啸与这些报告大致一致。海啸模型进一步表明，与2004年不同，1797年和1833年的印度洋海啸主要指向印度次大陆以南。在南纬0.7°到2.1°之间，潮间带没有1797年和1833年的珊瑚头，这表明地震间的淹没现在几乎等于伴随这些地震的同震出现。因此，沿这一巨型逆冲断层范围积累的震间应变沿着已接近或超过了1797年和1833年释放的水平。
Large uplifts and tilts occurred on the Sumatran outer arc islands between 0.5° and 3.3°S during great historical earthquakes in 1797 and 1833, as judged from relative sea level changes recorded by annually banded coral heads. Coral data for these two earthquakes are most complete along a 160-km length of the Mentawai islands between 3.2° and 2°S. Uplift there was as great as 0.8 m in 1797 and 2.8 m in 1833. Uplift in 1797 extended 370 km, between 3.2° and 0.5°S. The pattern and magnitude of uplift imply megathrust ruptures corresponding to moment magnitudes (M_w) in the range 8.5 to 8.7. The region of uplift in 1833 ranges from 2° to at least 3.2°S and, judging from historical reports of shaking and tsunamis, perhaps as far as 5°S. The patterns and magnitude of uplift and tilt in 1833 are similar to those experienced farther north, between 0.5° and 3°N, during the giant Nias-Simeulue megathrust earthquake of 2005; the outer arc islands rose as much as 3 m and tilted toward the mainland. Elastic dislocation forward modeling of the coral data yields megathrust ruptures with moment magnitudes ranging from 8.6 to 8.9. Sparse accounts at Padang, along the mainland west coast at latitude 1°S, imply tsunami runups of at least 5 m in 1797 and 3–4 m in 1833. Tsunamis simulated from the pattern of coral uplift are roughly consistent with these reports. The tsunami modeling further indicates that the Indian Ocean tsunamis of both 1797 and 1833, unlike that of 2004, were directed mainly south of the Indian subcontinent. Between about 0.7° and 2.1°S, the lack of vintage 1797 and 1833 coral heads in the intertidal zone demonstrates that interseismic submergence has now nearly equals coseismic emergence that accompanied those earthquakes. The interseismic strains accumulated along this reach of the megathrust have thus approached or exceeded the levels relieved in 1797 and 1833.