Quake energy has potential to further rattle West Sumatra

Tuesday, August 18, 2009
By nias

Padang, W Sumatra (ANTARA News) – A series of aftershocks which rattled West Sumatra province on Sunday and Monday (Aug 16 and 17) followed the quakes which struck the region back in 2007.

An earthquake expert of the Indonesian Institute of Sciences (LIPI) Danny Hilman Natawidjaja made the remarks on Monday and reminded the people especially in West Sumatra after 14 earthquakes shook the province in a couple of days in August.

“Certainly, they (series of quakes) were related to the 2007 tremors. Based on our research in Mentawai islands district, this area still has a great deal of earthquake energy,” Natawidjaja disclosed.

Based on researches in recent years, LIPI had once warned against some potential strong tremors in the province which required the alertness of many circles.

“Of course, the people living in the coastal areas of West Sumatra must be alert, but not panic,” Natawidjaja, who carried out a joined quake research with Kerry Sieh, a geological expert from the California Technological Institute (Caltech) in 2008, said.

Both experts conducted research of earthquake history of the Mentawai Islands.
The researchers found four tsunami cycles during the last 700 years, namely from the 1350 to 1380, 1606 to 1685, and 1797 to 1833.

Natawidjaja admitted that at present the threat of earthquakes in West Sumatra has been increasing. The quake location has even become closer to the (aftershock) sources that can trigger strong earthquakes.

The earthquakes which were happening now were located in a large fringe under the sea around Siberut island. Some of the centers which could trigger a strong earthquake are located in the Siberut-Sipora-Padang line, he said.

“(We) need to stay alert. However, once again do not panic,” Natawidjaja who obtained his doctorate from the California Institute of Technology, cited.

According to him, his side cannot predict when the big Sumatra earthquakes would strike, it could be in the next two or 10 years.

“Therefore, the people and local governments should increase their alertness,” he reminded.

He also expressed hope that the local people could be given safety training exercises in anticipation of the tremors, while the local administrations and related institutions have also to prepare evacuation facilities.

On Sunday (Aug.16), three earth quakes rattled the West Sumatra province respectively measuring 6.9, 5.2, and 5.6 on the Richter scale, leaving four people injured.

The 6.9 richter scale quake struck at 2.38 pm Western Indonesia Standard Time (WIB) at a depth of 32 km, some 43 km southeast of Siberut, Mantawai district, West Sumatra, the Meteorology, Climatology, and Geophysics Agency (BMKG) said.

The epicenter of the quake was located at 1.64 degrees south latitude and at minus 99.12 degrees east longitude, the BMKG said.

However, there was no immediate reports on casualties.

The second tremor measuring 5.2 on the Richter scale struck at 3:13 pm WIB and its epicenter was located 10 km under sea surface, 1.95 degrees south latitude and 100.02 degrees east longitude, 50 km north east of Mentawai island.

The third quake measuring 5.6 on the Richter scale struck at 3.23 pm WIB and its epicenter was located at a depth of about 10 km under sea surface, 1.99 degrees south latitude and 99.85 degrees east longitude, about 81 km south west of Padang.

The shocks, however, did not have the potential to trigger tsunamis.

Meanwhile, coordinator for the provincial relief agency, Ade Edward said that he had received reports from some districts like Agam, Mentawai and Pesisir Selatan, saying that there were no casualty reports.

“We call on the people not to worry, but the officials of the disaster relief agency should remain alert,” Ade Edward added.

At the moment, four visitors at the Plaza Andalas market sustained injuries after the ceiling cover broke and fell on them, after which they were rushed to the Yos Sudarso hospital in the city, Chief of West Sumatra provincial disaster relief agency, Sudirman Gani, said.

On Monday, a series of aftershocks continued to hit Padang, after a powerful quake rattled the area the previous day.

The Meteorology, Climatology and Geophysics Agency in its website noted four aftershocks had jolted Padang since a major quake measuring 6.9 on the Richter scale hit West Sumatra on Sunday.

Despite the spate of aftershocks the local people carried out their daily activities and business as usual.

Chief of the Padang city police Chief Commissioner Boy Rafli Amar said on Monday security situation in the city was secure following the major quake on Sunday.
“No theft was reported. Only a few homes were damaged but there was no fatality,” he said.

A spokesman for the Mentawai Islands district which bore the brunt of Sunday`s earthquake, said the residents who fled to hills on Sunday had returned home.

According to the Meteorology, Climatology, and Geophysics Agency, he added, the quake`s epicenter was located in Mentawai Strait, so that there was practically no possibility of a tsunami.

On December 26, 2004, a magnitude 9.3 Richter Scale, the deadliest earthquake in the last 40 years, which triggered devastated tsunami, hitting Nias district in North Sumatra and major part of the Nanggroe Aceh Darussalam (NAD) province, left about 200 thousand people dead and thousand others went missing.

Indonesia is prone to seismic upheaval due to its location on the so-called Pacific “Ring of Fire”, an area of volcanoes and fault lines encircling the Pacific Basin.

In the meantime, many Padang residents have started setting up tents outside their homes.

In addition, an earthquake expert of the Andalas University, Badrul Mustafa also asked the local people to keep watch for aftershocks of higher intensity.

“The series of quakes this time were fresh ones. Not just quakes which followed those which struck two years at seeking new stability,” Badrul said in Padang on Sunday.

“But let us pray that the 6.9 strong quake was the main one, and the next ones were merely secondary shocks of smaller magnitude,” the Unand rector assistant said.

Therefore, he reminded the people of West Sumatra to watch out for possible stronger quakes. – Source: Antara, 18 August 2009.

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