This is still a mystery, said the problem expert because the Cianjur earthquake was not the Cimandiri fault

This is still a mystery, said the problem expert because the Cianjur earthquake was not the Cimandiri fault

Brother Center | Lecturer at the Faculty of Geological Engineering, Padjadjaran University (Unpad) Ismawan, doubts that the cause of the earthquake with a magnitude of 5.6 in Cianjur, West Java, on Monday (21/11) was the movement of the Cimandiri Fault.

One that supports this hypothesis is the location of the epicenter of the earthquake which is far from the stretch of the Cimandiri Fault.

“What is clear, I believe this is not part of the Cimandiri fault, even though the direction is the same,” Ismawan said as quoted from the Unpad website, Tuesday (22/11).

This is still a mystery, said the problem expert because the Cianjur earthquake was not the Cimandiri fault
This is still a mystery, said the problem expert because the Cianjur earthquake was not the Cimandiri fault

Ismawan explained that the Cugenang area, which became the epicenter of the Cianjur earthquake, is about 10 kilometers north of the Cimandiri fault line. Meanwhile, the Cimandiri fault line starts from Palabuhanratu and then stretches eastward and turns north around the epicenter of yesterday’s earthquake.

This assumption is also strengthened by the results of previous studies which stated that the width of the Cimandiri fault is around 8-10 meters. In addition, the contours of the Cimandiri fault have a slope to the south, so that the location of the epicenter of the earthquake with a depth of 10 kilometers is certain to be outside the fault line.

In his analysis, Ismawan revealed the possibility that this earthquake was caused by a new fault movement that not many people knew about. It is said that not many people know because it could be that the traces of the fault alignment are covered by several factors.

If you look at the location of the epicenter which is close to Mount Gede, it is possible that the traces of the fault were covered by volcanic deposits.

“This is possible because if there are old faults there are usually traces of alignment indicating that there was a fault there. Due to volcanic rock there are no visible traces of alignment,” he said.

Ismawan said, judging from the focal mechanism of the Cianjur earthquake, there are two possible unidentified fault lines, namely: west-east or north-south.

However, most likely, the fault line is heading west-east. Ismawan also denied that the earthquake was caused by volcanic activity.

“On the contrary, there is concern that the fault activity will trigger volcanic activity or not,” he said.

This is still a mystery, said the problem expert because the Cianjur earthquake was not the Cimandiri fault
This is still a mystery, said the problem expert because the Cianjur earthquake was not the Cimandiri fault

With a severe impact, Ismawan said, yesterday’s Cianjur earthquake had quite a large force. This was compounded by the location of the epicenter which was on land and the depth of the earthquake which was quite shallow, which was 10 kilometers.

This caused many of the buildings on it to be badly damaged.

“Faults on land will not cause a tsunami, but the primary result is that many buildings collapse. If the depth is shallow enough, even a small earthquake can be damaging,” he said.

Therefore, the Cianjur earthquake event became a valuable lesson for the people of Indonesia, especially the people living in the fault area.

Analysis of earthquakes triggered by new fault movements indicates that there could be many new faults that have not been identified and can trigger quite serious earthquakes.

“Yesterday, an incident in an area where there had not been any mention of a fault turned out to be a quite large earthquake. Hopefully this will serve as a lesson,” said Ismawan

In addition, the impact of earthquake events is not only seen from the magnitude, but also the depth. An earthquake with a small magnitude, but with a shallow depth will still have a big effect.

Ismawan also reminded the public to remain vigilant about the dangers of tectonic earthquakes. Education and socialization regarding fault areas need to be strengthened in the community, especially for people who actually live in fault lines.

This encourages people to become more aware of the potential of the fault.

“Although in our area it is stated that it is far from faults, we do not know that there are actually several cracks that we may not know yet,” he said.

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