Earthquake In Malang Is Not A Megathrust Earthquake Because It Is In The Benioff Zone

PHOTO VIA ANTARA/BMKG

JAKARTA - The 5.3 magnitude earthquake that shook the southern direction of Kepanjen City, Malang Regency, East Java was not a megathrust earthquake because its center was in the Benioff zone.

"This earthquake is not a megathrust earthquake because its center is not in the contact area between plates, but is under the megathrust zone, namely the part of the plate that has started to dip, known as the Benioff zone," said the Coordinator for Earthquake and Tsunami Mitigation, Meteorology, Climatology and Geophysics Agency (BMKG) Daryono, quoted by Antara, Friday, October 22.

Based on the BMKG analysis, the earthquake has an updated parameter with a magnitude of 5.1. The epicenter is located at coordinates 8.81 degrees south latitude - 112.49 degrees east longitude, precisely at sea at a distance of 75 km south of Kepanjen City, Malang Regency, East Java with a depth of 98 km.

The earthquake south of East Java was a medium-depth earthquake caused by deformation or faults in the slab of the Indo-Australian Plate which was subducted under the Eurasian Plate in the south of East Java.

Daryono explained the results of the analysis of the source mechanism showed that the earthquake had a thrust fault mechanism due to the presence of compressive forces on tectonic plates.

The earthquake shock was felt strong enough in the Blitar area to reach the MMI III-IV intensity scale, causing damage to buildings in the form of houses in Wlingi District, prayer rooms in Binangun District, and Serang Village Office buildings, Panggungrejo District.

Meanwhile, in Ponorogo, Malang, Pasuruan, Nganjuk, Mojokerto, Pacitan, Lumajang, Jember, and Trenggalek, shocks were felt on the MMI II-III intensity scale. As a result, most of the residents ran out of their houses because they were surprised by the sudden strong shock.

The modeling results show that the earthquake south of East Java has no potential for a tsunami because its magnitude is relatively small at medium depths, so it does not disturb the seawater column, said Daryono.

As of 13.00 p.m., the results of BMKG monitoring have not shown any aftershock activity.