The Oldest Fault in West Java Is the Cause of the Cianjur Earthquake

Cianjur Earthquake Death Victims in 21 November 2022 (Ikbal Selamet/detikcom)

The Cianjur earthquake that occurred on Monday afternoon (11/21) to date caused 162 people to die, and at least 700 people were injured. This deadly earthquake was even felt until Jakarta. The earthquake was allegedly due to the movement of the Cimandiri fault.

“It is suspected that this is a movement of the Cimandiri fault to move back,” said BMKG Head Dwikorita Karnawati, Monday (11/21/2022) quoted.

According to Dwikorita, the epicenter was around Sukabumi-Cianjur, which was an earthquake due to a shear fracture.

Based on the official report of the Bandung Geophysics Station as of June 2022, it was explained about the facts and historical facts of the Mandiri fault, and activities that were often active lately, especially in recording records last June.

The Cimandiri Fault is the oldest (limestone), stretching starting from the Bay of Pelabuhan Ratu continuously to the east through the Cimandiri Valley, Cipatat Rajamandala, Mount Tangguban Parahu – Burangrang and allegedly continuing to the northeast to Subang.

Overall, this fault pathway is northeast-southwest with a horizontal fault type to oblique.

The Cimandiri fault route is in the Rajamandala segment, in the northeast – Southwest. This fault activity was shown by a significant earthquake, namely in 1910 in Padalarang, in 1982 in Cianjur, Rajamandala, and in 1844 in the Cianjur region.

The latest significant earthquake occurred on March 10, 2020, with a Magnitude of 5.1 which shook Kab. Sukabumi and its surroundings cause damage to the area.

Based on the report, during June 2022, in the area of ​​West Java and its surroundings, there have been recorded 60 earthquake events with magnitude varying between 1.3 to 4.2, with the number of shallow earthquakes (H <60 km) as many as 57 events and 3 Earthquake Events ( 60 ≥ H <300 km) and Inner Earthquake (H≥ 300 km) Zero Events.

Earthquakes occurred on land as many as 28 events with 27 events caused by cesarean activities, namely: Cimandiri fault 16 events, the garsela fault 2 events,

Furthermore, the Head of the BMKG earthquake and tsunami mitigation, Daryono, Tuesday (11/22/2022) said, Cianjur was indeed one of the active and complex seismic areas that made it one of the earthquake-prone areas, besides Sukabumi, Lembang, Purwakarta, and Bandung.

“The results of BMKG monitors in the area often occur earthquakes with various variations and depths,” he said.

Related to complexity, he continued, the area is an active earthquake path area such as the existence of the Cimandiri, Padalarang, Lembang, Cirata, and many minor faults in the region, making the area a permanent earthquake area.