Head of Mitigation Division Earthquake and Tsunami BMKG Daryono said, in the last two days, on September 3 and September 4 2020, BMKG recorded four shallow crust earthquakes (shallow crustal earthquake) which occurred on the mainland of Java Island.
“An earthquake due to active fault activity, even though the magnitude is not too large, should be watched out for. The existence of an active fault whose path is close to residential areas is certainly very risky to cause damage and also casualties, “said BMKG Head of Earthquake and Tsunami Mitigation Daryono when contacted. Kompas.com, Friday (4/9/2020).
The four earthquakes that occurred during the last two days were as follows:
- Dieng earthquake with a magnitude of 2.2 on September 3, 2020 at 05.00 WIB with the epicenter location at coordinates 7,12 South Latitude and 109.78 East Longitude, precisely on land at a distance of 14 km north of Dieng, Banjarnegara, Central Java. As for the depth of 10 km, and felt in Dieng on a scale I-II MMI.
- The Sukabumi earthquake with a magnitude of 2.7 on September 3, 2020 at 20.42 WIB, the epicenter location at coordinates 7.08 latitude and 106.95 east longitude, to be precise on land at a distance of 18 km southeast of Sukabumi City, West Java. Depth of 10 km, and felt in the District of Nyalindung Sukabumi with the MMI II-III intensity scale.
- The Bantul earthquake with a magnitude of 3.1 on September 4, 2020 at 00.07 WIB, the epicenter location is at coordinates 7.93 south latitude and 110.48 east longitude on land at a distance of 15 km northwest of Gunungkidul, Yogyakarta. Depth of 5 km and felt in Bantul with the MMI II intensity scale.
- The Sukabumi earthquake had a magnitude of 3.3 on September 4, 2020 at 13.30 WIB, the epicenter location was at coordinates 7,11 South Latitude and 106,93 East Longitude, precisely on land at a distance of 20 km southeast of Sukabumi City, West Java. It is 4 km deep and is felt in Nyalindung sub-district, Sukabumi, with the MMI II-III intensity scale.
Daryono said the Dieng earthquake occurred because it was triggered by a fault around the Dieng Mountains.
The Sukabumi earthquake was triggered by active fault activity in the Cipamingkis zone.
Meanwhile, the Bantul earthquake was triggered by enlargement activity in the Opak Fault zone.
BMKG said, to cause damage to houses, earthquakes due to shallow active faults do not have to be of large magnitude.
“Since 2015, on the island of Java alone, there have been at least five destructive earthquakes triggered by active fault activity with a shallow depth with a magnitude less than 5.0 (M <5.0)," he said.
The earthquakes that have occurred and damaged include:
- Madiun earthquake with a magnitude of 4.2 on June 25, 2015.
- Pangalengan earthquake with a magnitude of 4.2 on November 6, 2016.
- The arrowroot earthquake with a magnitude of 3.7 on July 18, 2017.
- The Banjarnegara earthquake with a magnitude of 4.4 on April 18 2018 damaged more than 316 houses.
- Lebak earthquake with a magnitude of 4.4 on July 7, 2018.
“With the aforementioned facts and data, active fault activity on land and mainly close to residential areas certainly deserves to be watched out for,” said Daryono.
As a mitigation effort, BMKG appealed to the public to create earthquake resistant houses and understand what to do when an earthquake occurs.
Daryono said the earthquake did not kill and injure.
According to him, what actually happened was a low-quality wall building that did not comply with the earthquake-resistant building code so that it could collapse and hit its occupants.