The Threat of Catastrophic Disasters in Java

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JAKARTA, KOMPAS -- Active fault lines in Java may trigger catastrophic disasters, considering the population density of potentially affected areas. Detailed studies on the Lembang fault in West Java can be used to transform spatial planning. However, more studies are required on the active faults below other cities, including Jakarta.

“Latest studies of earthquakes in Java found in quality international journals with strict peer reviews cannot be neglected. Scientifically, studies such as those on the Lembang fault must be able to clear up doubts about the fault’s activity and how to mitigate for it,” Bandung Institute of Technology geodesist and earthquake expert Irwan Meilano said on Monday.

A scientific study on the activities of faults near major cities in Java, including Jakarta, was published by Endra Gunawan and Sri Widiyantoro in the Journal of Geodynamics. A study on the Lembang fault was published by Mudrik R Daryono, Danny H Natawidjaja, Benjamin Sapiie and Phil Cummins in the journal Tectonophysics.

Irwan said Mudrik’s study on the Lembang fault, which he used in his dissertation, has detailed information, a map on the fault line and data on past earthquakes’ maximum strength. Endra’s study was regional and further research is required to detail all the faults in each segment. “Mitigation on the Lembang fault line can be started by studying Mudrik’s data,” he said.

Mudrik, a geologist at the Indonesian Institute of Sciences’ (LIPI) geotechnology center, said he created a model of the Lembang fault line based on the light detection and ranging (LIDAR) map with a 90-centimeter resolution. “There was cooperation with Australia for the dissertation. They funded the purchase of a map worth Rp 700 million [US$49,688.37]. Without it, it would have been impossible for me to create a detailed map of the Lembang fault,” he said.

Mudrik, along with other researchers at the National Center of Earthquake Studies (PuSGeN), details fault lines in Java, including in Jakarta’s surrounding area. “However, we have a limited budget. To find the fault lines, we used free maps with a 30-meter resolution. Recently, a Geospatial Information Agency [BIG] map with 8.5-m resolution was made. This helps with identification in other areas. We have yet to do this for Jakarta,” he said.

The rate of movement of the faults in Jakarta is very small. Therefore, the deformation on the surface is also very small. “The morphology is difficult to see as it is covered by vegetation and dense buildings. We need a map with a resolution of below 1 m, like the LIDAR,” Mudrik added.

Support for research

According to him, securing research funding to create detailed maps of Indonesia’s active fault lines, including those in Java, had not been easy. “Last year, we

proposed research funding to the Research, Technology and Higher Education Ministry for research on the active faults in Semarang. It was rejected,” he said.

This despite a 2015 study by Ngoc Nguyen, Cummins and a team from Australian National University concluding that massive earthquakes with catastrophic impacts may strike Java. If an earthquake as strong as the one in 1699 is to hit the capital today, the number of casualties may reach 100,000. This is based on the city’s population density and building destruction risk.

The Meteorology, Climatology and Geophysics Agency’s (BMKG) head of earthquake information and tsunami early warning division, Daryono, said such studies were within the realm of academics and research agencies.

With respect to this, the administrations of a number of disaster-prone regions have come up with disaster anticipatory plans. The Jakarta administration, for instance, has come up with mitigation plans that it formulated into regional bylaws.

Jakarta land and spatial planning agency head Benni Agus Candra said Regional Bylaw No. 1/2012 on Jakarta spatial plan 2030 had accommodated the city’s proneness to disasters, including earthquakes, adding that disaster evacuation areas have been prepared.

West Java Governor Ridwan Kamil said his administration was preparing a resiliency culture blueprint for locals in disaster-prone regions. (AIK/SYA/GER/DKA/HLN/CHE)

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