New Fault Found in West Sumatra, Can Cause Heavy Damage

TheIndonesia.id - A number of experts from Bandung Institute of Technology (ITB) and National Research and Innovation Agency (BRIN) provided support to the Meteorology, Climatology, and Geophysics Agency (BMKG) for the identification of a new fault in West Sumatra. BRIN and ITB push for further research following the deadly earthquake caused by the fault last week.

A press release received by Antara in Jakarta, Sunday, March 6, 2022, stated that in a webinar organized by BMKG, Prof. Danny Hilman Natawidjaja from BRIN and Prof. Sri Widiyantoro from ITB agreed to support the results of the BMKG identification.

Based on the distribution of aftershocks points, morphological patterns and the distribution of clusters of landslide points on slopes cut by faults and the distribution of clusters of levels of building damage described by the Head of the Technical Seismology Center and the Head of the BMKG Earthquake and Tsunami Center, it can be said that it is a new fault.

"However, it is necessary to continue with a more in-depth study, especially related to the presence and distribution of surface ruptures or tearing of the soil and rock surfaces as an indication of a zone cut by the fault," said the two experts.

Regarding the findings, Head of BMKG Dwikorita Karnawati warned the local government to be aware of the complexity of the active fault system because spatial planning has a major role in disaster mitigation efforts. "The discovery of this new fault needs to be followed up by determining the boundary of the hazard zone where residential communities or vital buildings should not be built without implementing earthquake-resistant building construction for safety reasons," she said.

Dwikorita explained that proper spatial planning will reduce the impact of disasters, both in terms of material losses and loss of life. She emphasized the need for law enforcement related to the implementation of regional spatial plans in the form of not issuing permits in locations that have a high level of vulnerability, as well as preparing clear disaster maps and zoning.

Based on the study in the northern part of West Sumatra conducted by BMKG, previously there were only faults in Angkola and Sianok. However, after an in-depth study after the West Pasaman earthquake, a new fault has been found, which is named the Talamau Fault.

The new fault is classified as a dextral strike-slip fault which is the hallmark of the earthquake source mechanism of the Great Sumatran Fault. The fault has the potential to cause earthquakes up to the Modified Mercalli Intensity (MMI) VII-VIII scale. On this intensity scale, the earthquake that occurs can knock down building structures or houses with moderate to severe levels of damage, so that if not anticipated, it can be fatal for residents.

Dwikorita emphasized that with the increasing number of active fault segments found in the West Sumatra region, the earthquake sources that need to be watched out for and mitigated are not only in the Megathtust zone and the Mentawai fault which is located at sea. "The identification of a new fault is a marker of a new tectonic fault pattern, therefore it needs to be monitored and mitigated comprehensively because so far the zone is considered relatively safe," she said.

Furthermore, Dwikorita said that community relocation could be an option in mitigation. However, if it is difficult to do so, the community needs to be continuously taught so that they can better understand the consequences if they continue to survive in high disaster-prone locations.