1861 Sumatra earthquake

The 1861 Sumatra earthquake occurred on February 16 and was the last in a sequences of earthquakes that ruptured adjacent parts of the Sumatran segment of the Sunda megathrust. It caused a devastating tsunami which led to several thousand fatalities. The earthquake was felt as far away as the Malay peninsula and the eastern part of Java.[2] The rupture area for the 2005 Nias–Simeulue earthquake is similar to that estimated for the 1861 event.

1861 Sumatra earthquake
Local dateFebruary 16, 1861 (1861-02-16)
Magnitude8.5 Mw
Epicenter1.0°N 97.5°E / 1.0; 97.5
FaultSunda megathrust
Areas affectedSumatra, Dutch East Indies
Tsunamiyes
Casualtiesseveral thousand[1]
Plate tectonic setting of Sunda megathrust
Rupture areas for the 1861, 1833 and 2004 earthquakes and area of main shock and aftershocks for the 2005 event, showing similarity to 1861 quake

Background

The island of Sumatra lies on the convergent plate boundary between the Indo-Australian Plate and the Eurasian Plate. The convergence between these plates is highly oblique near Sumatra, with the displacement being accommodated by near pure dip-slip faulting along the subduction zone, known as the Sunda megathrust, and near pure strike-slip faulting along the Great Sumatran fault. The major slip events on the subduction zone interface are typically of megathrust type. Historically, great or giant megathrust earthquakes have been recorded in 1797, 1833, 1861, 2004, 2005 and 2007, most of them being associated with devastating tsunamis. Smaller (but still large) megathrust events have also occurred in the small gaps between the areas that slip during the larger events, in 1935, 1984, 2000 and 2002.[3]

Damage

Villages along the seaward side of the Batu Islands were devastated.[2] The combined effects of the earthquake and tsunami caused several thousand fatalities.[1]

Characteristics

Earthquake

There is evidence of coseismic uplift of Nias, with exposure of reefs and rock piers. There were six major aftershocks over the next seven months, the last of which, on September 27, caused a damaging tsunami.[2]

Tsunami

At least 500 km of coastline were affected by the tsunami with run-ups of up to 7m recorded on the southwest side of Nias.[2]

See also

References
  1. Tsunami Laboratory. "Destructive historical tsunamis at the western coast of Sumatra". Archived from the original on 3 October 2009. Retrieved 2009-11-06.
  2. Newcomb, K.R.; McCann W.R. (1987). "Seismic history and seismotectonics of the Sunda Arc" (PDF). Journal of Geophysical Research. 92 (B1): 421–439. Bibcode:1987JGR....92..421N. doi:10.1029/JB092iB01p00421. Retrieved 2009-11-06.
  3. Natawidjaja, D. H.; Sieh K.; Chlieh M.; Galetzka J.; Suwargadi B.W.; Cheng H.; Edwards R.L.; Avouac J.-P. & Ward S. N. (2006). "Source parameters of the great Sumatran megathrust earthquakes of 1797 and 1833 inferred from coral microatolls" (PDF). Journal of Geophysical Research. 111 (B06403): n/a. Bibcode:2006JGRB..111.6403N. doi:10.1029/2005JB004025. Archived from the original (PDF) on 2009-10-12. Retrieved 2009-10-24.
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