KOMPAS.com – On Thursday evening (7/11/2019) at 21.27 western Indonesia time Pacitan Regency and its surroundings were shaken by tectonic earthquakes.
BMKG analysis results show that the earthquake is 3.1 M.
The epicenter is at coordinates -8.23 south latitude and 111.13 east longitude or exactly on land 4 km southeast of the city of Pacitan at a depth of 11 km.
The impact of the earthquake last night showed that shocks were felt in Pacitan, Kebon Agung, Tamperan on the MMI Intensity II-III scale, i.e. the shocks were felt at home, as if a truck was passing by.
According to Kompas.com, Daryono as head of the earthquake and tsunami relief section said BMKG said the earthquake that shook Pacitan was a kind of shallow earthquake (shallow earthquake in the crust) due to active error activity.
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This application is considered from the location of the epicenter and depth of the hypocenter.
"Looking at the location of the epicenter, there is a strong suspicion that the cause of the earthquake was Grindulu's error. This mistake was made in the northeastern southwestern southwestern district, "said Daryono on Friday (11/08/2019).
The district is the most important era because better human life began. The Quaternary era that began about 600,000 years ago.
Daryono continued, the mechanism of the Pacitan earthquake was slipping north-east-south-west.
"This is in line with the characteristics of the Grindulu glitch, which is indeed a sliding glitch," he said.
About Grindulu's wine
In some scientific publications, the Grindulu error line crosses five districts, namely the districts of Bandar, Nawangan, Unung, Arjosari and Donorojo.
The main glitch itself has minor glitches that are spread across several neighborhoods in Pacitan Regency.
"Some experts suspect that the Grindul fault that divides the Pacitana Regency structure is reaching the slopes of Mount Wilis in Ponorogo Regency," he continued.
Although the earthquake did not have a major impact, the earthquake from the center of the Pacitan continent is proof that the Grindulu fault structure is still active, so be careful.
"Unfortunately, the entire fault line has not been reproduced in detail, so in the event of an earthquake last night it seems to be an important moment for a more accurate diagnosis of Grindulu's fault," said Daryono.
Daryono added that exploration of ancient seismic history (paleoseismology) recorded in rock layers thousands of years along the Grindulu River could help establish clues, revealing the periodicity of a strong earthquake that occurred in the past due to fault structure.
The investigation must be carried out so that Grindulu's defect is ignored, for example the Pak Yogyakarta defect, which proved to be active again, causing a major earthquake on May 27, 2006.
It is necessary to take mitigation measures so that people understand the importance of building houses with strong and safe structures during an earthquake.
If construction is expensive, there are other options for building houses from light materials, such as wood and bamboo, to be attractive.
Earthquakes do not kill and do not hurt, but weak buildings that collapse and touch the inhabitants causing losses.
The Pacitan Regency region is indeed one of the most susceptible to the tectonic earthquake in East Java.
"Pacitan falls into the high risk category because it encounters the Megathrust zone in southern Java and is also on the Grindulu failure line. That is why it is important to study the earthquake threat and risk in this region, "he concluded.
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BMKG monitoring results until Friday morning (8/11) at 8.00 WIB was not active after the secondary shock.
Until now, there have been no reports of damage to buildings due to the earthquake.