7.3 Magnitude Earthquake Strikes off the West Coast of Sumatra, Indonesie – Jan 10, 2011


An earthquake measuring 7.3 on the Richter scale struck off the west coast of Indonesia’s Northern Sumatra on Wednesday, the US Geological Survey reported, but there were no immediate reports of casualties.

A tsunami warning was issued by the Pacific Tsunami Warning Center, and Indonesia also issued a tsunami warning but lifted it about two hours later.

The quake, which had a depth of 29 kilometers, hit at 2:37 a.m. around 261 miles southwest of Banda Aceh, the capital of Aceh province on Indonesia’s Sumatra island.

An official at Indonesia’s Meteorology and Geophysics Agency said there were no immediate reports of casualties.

“The quake was in the sea and a tsunami warning is in force, but so far we have no reports of casualties or damage,” Suharjono, the agency’s technical chief, told AFP before the warning was lifted.

The agency initially reported a 7.6-magnitude quake, but later downgraded that to magnitude 7.1.

The Pacific Tsunami Warning Center said the threat of a widespread tsunami did not exist but added: “There is a very small possibility of a local tsunami that could affect coasts located usually no more than a hundred kilometers from the earthquake epicenter.”

The Indonesian agency also reported three aftershocks of magnitude 5.4 and 5, respectively about 30 minutes and two hours after the initial quake.

In Banda Aceh, the ground shook for 30 seconds and terrified residents rushed out of their homes, but they returned indoors shortly after, an AFP reporter there said.

Some coastal residents had moved further inland, taking shelter in mosques or camped by the roadside as a precautionary measure, but there was no sense of panic, he said. The aftershocks were not felt in Banda Aceh, he added.

In December 2004, a giant 9.1-magnitude quake off the coast of Aceh province on the northern tip of Sumatra triggered a tsunami in the Indian Ocean that claimed 220,000 victims, with Indonesia accounting for three-quarters of the figure.

USGS report

Magnitude 7.3
Location 2.396°N, 93.175°E
Depth 29.1 km (18.1 miles)
Distances 423 km (262 miles) SW of Banda Aceh, Sumatra, Indonesia
537 km (333 miles) SW of Lhokseumawe, Sumatra, Indonesia
951 km (590 miles) W of KUALA LUMPUR, Malaysia
1789 km (1111 miles) WNW of JAKARTA, Java, Indonesia
Location Uncertainty horizontal +/- 16.3 km (10.1 miles); depth +/- 8.1 km (5.0 miles)
Parameters NST= 75, Nph= 75, Dmin=504.3 km, Rmss=1.49 sec, Gp= 68°,
M-type=regional moment magnitude (Mw), Version=6
  • Magnitude: USGS NEIC (WDCS-D)
    Location: USGS NEIC (WDCS-D)
Event ID usc0007ir5

Indonesian BMKG report

Terjadi pada Lokasi Magnitude Kedalaman Wilayah
11 Januari 2012
04:00:53 WIB
2.39 LU – 93.18 BT 5.0 SR 59 Km 325 km BaratDaya KAB-SIMEULUE
11 Januari 2012
02:46:14 WIB
2.29 LU – 92.85 BT 5.0 SR 10 Km 362 km BaratDaya KAB-SIMEULUE
11 Januari 2012
02:02:52 WIB
2.14 LU – 94.01 BT 5.4 SR 204 Km 237 km BaratDaya KAB-SIMEULUE
11 Januari 2012
01:36:57 WIB
2.41 LU – 93.09 BT 7.1 SR 10 Km 334 km BaratDaya KAB-SIMEULUE
11 Januari 2012
01:36:54 WIB
2.32 LU – 92.82 BT 7.6 SR 10 Km 365 km BaratDaya KAB-SIMEULUE

As you can read on the BMKG report, in fact  there were two earthquakes of 7.6 and 7.1 with an interval of 3 minutes.

Source and author: bmkg * earthquake.usgs.gov * jakartaglobe


Comments are closed.