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Banten jolt revives megathrust earthquake fears
According to Indonesian Institute of Sciences’ (LIPI) data, thousands of megathrust earthquakes have occurred since 2000. Of the total, 85 megathrust earthquakes had magnitudes greater than 5.0.
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A resident in Padeglang, Banten, assesses his house on Aug. 3 after a 6.9-magnitude earthquake shook the area the previous evening. (Antara/Asep Fathulrahman)
T
he 6.9-magnitude earthquake that shook the southwestern coast of Banten on Friday evening has resurfaced fears of a megathrust earthquake similar to the one that caused the 2004 Indian Ocean tsunami that devastated Aceh.
The Banten quake, which occurred at 7 p.m., killed eight people and damaged around 1,000 houses and other buildings, mostly in Pandeglang, Lebak and Serang in Banten as well as Sukabumi and Cianjur in West Java.
The Meteorology, Climatology, and Geophysics Agency (BMKG) reported the earthquake was detected 147 kilometers southwest of Sumur, Banten, at a depth of 10 km. The agency issued a tsunami alert shortly after.
Volcanology and Geological Disaster Mitigation Center (PVMBG) head Kasbani explained that Friday’s quake was considered a megathrust earthquake as it was caused by subduction between the Indo-Australian plates and the Eurasian plates. The epicenter was located in the M7 megathrust zone, otherwise known as the Sunda Strait zone.
Megathrust earthquakes occur in megathrust zones, where the edges of two tectonic plates converge, forcing one underneath the other in a process called subduction. Most earthquakes caused by megathrust movements are small with a magnitude under 5.0. However, megathrust earthquakes can occasionally be very powerful and do significant infrastructure damages, cause tsunamis and claim lives.
According to Indonesian Institute of Sciences’ (LIPI) data, thousands of megathrust earthquakes have occurred since 2000. Of the total, 85 megathrust earthquakes had magnitudes greater than 5.0.
The largest was the 9.2-magnitude earthquake off the northern tip of Sumatra that caused the tsunami that swept across Aceh and Nias Island, North Sumatra, in 2004, killing 168,000 people.
