Earthquake Victims Evacuate
Residents of Mentawai Islands Regency, West Sumatra, must remain vigilant of the potential aftershocks caused by the Mentawai megathrust earthquake.
An earthquake rocked the Mentawai Islands, West Sumatra, on Monday (29/8/2022).
Residents of Mentawai Islands Regency, West Sumatra, must remain vigilant of the potential aftershocks caused by the Mentawai megathrust earthquake.
PADANG, KOMPAS - As many as 2,326 residents evacuated after a 6.4 magnitude earthquake shook Siberut Island in Mentawai Islands Regency, West Sumatra on Monday (Aug. 29). The government has prepared tents, logistics and soup kitchens for refugees.
According to data from Mentawai Islands Regional Disaster Management Disaster Agency (BPBD) on Monday afternoon, 2,326 refugees were spread across seven hamlets in Simaleg village, West Siberut district. While 704 people took refuge in South Dusun Betaet, 528 people were in North Dusun Betaet.
“The evacuation site is on a hill near a settlement,” said Novriadi, Mentawai Islands BPBD head, when contacted from Padang on Monday afternoon.
The local subdistrict and village administrations also prepared logistics and soup kitchens.
Residents began setting up emergency tents provided by the district administration in the refugee camps, according to Novriadi. The local subdistrict and village administrations also prepared logistics and soup kitchens.
Novriadi explained that residents fled out of fear of the aftershocks of the quake. However, the evacuation site is not too far so residents can easily and quickly return to their homes if the situation allows.
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Three relatively strong tectonic earthquakes hit Siberut Island and its surroundings early Monday morning. The first 5.2 magnitude earthquake occurred at 00:04 a.m. WIB, the second 5.9 magnitude earthquake occurred at 5:34 a.m. WIB and the third quake of 6.4 magnitude occurred at 10:29 a.m. WIB.
The three earthquakes occurred in almost the same location. The last 6.4 magnitude earthquake’s epicenter was 12 kilometers northwest of West Siberut at a depth of 24 kilometers or 0.99 degrees south latitude and 98.65 degrees east longitude.
Map of the location of the Mentawai-Siberut and Mentawai Pagai megathrusts.
Novriadi said the strongest earthquake was felt in Simaleg village as it was the closest to the epicenter. As of Monday afternoon, the earthquake caused serious damage to a Simaleg elementary school, moderate damage to a Catholic church and minor damage to a West Siberut junior high school and a Betaet community health center (Puskesmas).
Meanwhile, Mentawai Islands acting Regent Martinus Dahlan urged residents to remain alert of aftershocks and not to panic from unverified information. “Avoid activities on beaches and buildings that are prone to collapse,” he said.
Hendrikus Bentar, a resident of South Siberut, said residents also felt the earthquake in Muara Siberut. The 6.4 magnitude earthquake felt stronger and lasted longer compared to the previous two quakes. When the earthquake occurred, residents left their homes.
“The locals are safe for the time being but we must remain vigilant. No one has evacuated yet,” he said.
Although it was not as strong, the earthquake lasted a few seconds and caused hanging mirrors and water gallons to sway.
The earthquake was also felt in East Padang district, Padang municipality. Although it was not as strong, the earthquake lasted a few seconds and caused hanging mirrors and water gallons to sway.
Extremely strong
Suaidi Ahadi, head of the Meteorology, Climatology and Geophysics Agency’s (BMKG) at the Padang Panjang geophysics station, said that the three relatively strong earthquakes, including a 3 magnitude aftershock, occurred right in the Mentawai-Siberut megathrust segment. “This location can still trigger an 8.9 magnitude earthquake,” he said.
According to Suaidi, earthquakes can reach up to 8.9 magnitudes in the megathrust Mentawai area. The earthquakes exceeding 5 magnitude that occurred on Monday could reduce the maximum strength of an earthquake in the area but not as significantly. Suhaidi calculated that in terms of energy there needs to be at least 1,000 5.2 magnitude earthquakes or 100 6.8 magnitude earthquakes for the 8.9 magnitude earthquake potential to be exhausted. “We need to remain vigilant because an 8.9 magnitude earthquake can still occur. This information is not to instigate panic but to encourage vigilance,” he said.
The BMKG and BPBD tsunami warning community and disaster mitigation groups in West Sumatra, said Suaidi, always routinely encourage literacy and educate the public on being vigilant. In Padang, for example, the BMKG along with the Padang administration and other parties are building a tsunami warning community to be launched on Sept. 30.
Residents set up emergency tents on a hill where they are displaced near a settlement in Simaleg Village, West Siberut District, Mentawai Islands Regency, West Sumatra, after an earthquake rocked this area some time ago.
Padang State University center for disaster mitigation and earth observation head Pakhrul Razi said that the seismic gap zone is located in Mentawai. Meanwhile, areas in the northern and southern areas also saw several major earthquakes.
Energy release
Pakhrul further explained that the earthquakes that occurred on Monday (Aug. 29) in Mentawai Islands can also be interpreted positively. These earthquakes indicate that there has been a release of energy, even though it is not significant and there is still a potential for a stronger earthquake to occur. This also serves as a reminder for the public to be more aware of the risks of aftershocks.
“For the past two weeks, I have been worrying why there hasn’t been another earthquake. It has been a while, so I’m grateful. Earthquakes release their energy cumulatively. It is better that they’re released little by little so that we don’t really feel the effects,” he said.
The results of the analysis of the source mechanism showed that the earthquake moved upwards.
BMKG acting head of the earthquake and tsunami center, Daryono, explained that based on the location of the epicenter and the depth of the hypocenter, this was a shallow earthquake due to the subduction activity of the Mentawai-Siberut megathrust plate segment. The results of the analysis of the source mechanism showed that the earthquake moved upwards.
“The modeling result showed that this earthquake has no potential for a tsunami,” Daryono said in a written statement on Monday. As of 6:20 a.m., the BMKG recorded only one aftershock of 3.8 magnitude.
Daryono urged the public to remain calm and not to be influenced by unverified information. Residents were told to avoid buildings damaged by the earthquake. “Check and make sure the building where you live is earthquake proof or that there is no damage due to earthquake vibrations that threaten the stability of the building before returning home,” he said. (JOL)
(This article was translated by Kesya Adhalia)
