2,892 Schools Exist on Fault Lines

KOMPAS/PRAYOGI DWI SULISTYO

Students of state elementary school SD Negeri Tembong 1 in Kampung Tembol, Tembong village, Carita district, Pandeglang, Banten, board a military vehicle on Monday (7/1/2019). On the first day of school after the semester holiday, students cleaned up their classrooms and school yard because it was used as an evacuation post for survivors of the tsunami. The students went home early after their hard work

JAKARTA, KOMPAS -- The 2017 National Earthquake Source Map has mapped out the country’s land fault lines, even if most of them are not shown in detail. Based on this most recent map, 4 million Indonesians and 2,892 schools are located within danger zones, or within a 1-kilometer radius of a fault line.

“Eighty percent of our land fault lines are not well-mapped due to limited research, both in terms of funding and number of researchers involved. This should be among our top priorities moving forward as our country faces a massive threat of potential earthquakes,” Indonesian Institute of Sciences (LIPI) seismologist Danny Hilman Natawidjaja said in Jakarta on Thursday (10/1/2019).

Due to limited data and research on earthquake sources, most faults can only be identified after earthquakes occur, such as the Pidie Jaya fault that was found only after an earthquake in 2016. Danny also said researchers were able to improve their identification of the Palu-Koro fault after the earthquake on Sept. 28, 2018.

Periodical updates on earthquake sources by the National Earthquake Research Center (Pusgen) have also found new fault lines, previously unmapped due to limited data and research. On the 2010 National Earthquake Map, for instance, only four faults were mapped in Java. In the 2017 map, however, the number increased to 34. Nationwide, the number of mapped faults has increased from 81 in 2010 to 295 in 2017.

Based on the map, Pusgen researchers can calculate the number of schools, healthcare facilities, population and transportation infrastructure located within a 1- kilometer radius of the fault lines. Pusgen researcher Rahman Hanifa said the study was conducted with support from the National Development Planning Agency (Bappenas) and the National Disaster Mitigation Agency (BNPB).

The research results show 2,892 schools, 40 hospitals, 126 community health centers (Puskesmas) and more than 4.1 million individuals are within highly prone zones. Furthermore, 11 seaports, 21 bus terminals, two train stations, 237 stretches of provincial roads amounting to 652.3 kilometers, 31 stretches of railroad amounting to 83.3 kilometers and 15 toll roads amounting to 20.1 kilometers, are also within these highly prone zones.

More detailed research is required on the newfound fault lines to help improve disaster mitigation. Thus far, only West Java’s Lembang fault and the Palu-Koro fault following the Sept. 28 earthquake have been mapped at high resolution.

Spatial planning

Bandung Institute of Technology (ITB) professor of civil engineering and Pusgen chair Masyhur Irsyam said the presence of fault lines had been included in the considerations for spatial planning in other countries. A Pusgen study shows that,

since 1977, the United States has designated safe zones to be more than 150 meters from fault lines and more than 60 meters from fault branches.

In Taiwan, fault lines with past earthquakes measuring more than 7-magnitude have 100-meter safe zones on both sides of the lines. Meanwhile, fault lines with past earthquakes measuring more than 6-magnitude have 50-meter safe zones and fault lines with past earthquakes measuring less than 6-magnitude have 30-meter safe zones.

Following a comprehensive scientific study on fault lines in Wellington, New Zealand, safe zones of 50-90 meters, including a 20-meter margin of uncertainty, are applied on the country’s fault lines. In China, safe zones vary depending on the type of construction: 100 meters, 200 meters or 400 meters.

Rahma said Indonesia did not have a national regulation for safe zones on fault lines. Only the West Java administration has regulation on safe zones.

West Java Gubernatorial Decree No. 2/2016 stipulates that all construction in areas with disaster risk, especially around the Lembang fault, must be based on comprehensive studies on disaster risk and mitigation. The province also stipulated a 250-meter building-free zone on both sides of the Lembang fault. (AIK)