The National Disaster Mitigation Agency (BNPB) has called on regional administrations across the country to incorporate microzonation maps in urban planning to anticipate possible soil liquefaction.
“[We have to] conduct a nationwide microzonation project, so we will be able to map out areas that are prone to earthquakes and liquefaction,” said BNPB spokesman Sutopo Purwo Nugroho on Sunday as quoted by tempo.co.
This is urgent, he added, following soil liquefaction that occurred in Palu and Sigi regency, Central Sulawesi, in the aftermath of a 7.4-magnitude earthquake and subsequent tsunami.
According to Sutopo, soil liquefaction is a natural phenomenon that takes place when soil loses its strength and behaves like liquid due to stress, such as intense shaking during an earthquake.
He said a 2012 study by the National Geology Agency found that several areas in Palu were very prone to soil liquefaction. However, the city administration still allowed private developers to build residential complexes in their vicinity.
“Soil liquefaction in Palu resulted in more casualties and damages than other regions that were also affected by the earthquake,” Sutopo said.
Soil liquefaction is relatively unknown among the Indonesian public, including survivors and witnesses of the disaster. Previously, The Jakarta Post correspondent Ruslan Sangadji reported that on the morning after the quake, survivors referred to the phenomenon as “land tsunami”.
Witnesses said the “mud” rolled like ocean waves. Houses in Petobo, South Palu district, Palu shifted as much as 700 meters from their original locations.