Analysis of susceptible disaster region based on the peak ground acceleration and earthquake intensity in Mamasa 2018

Abstract

This study aims to know the susceptible disaster region based on peak ground acceleration and earthquake intensity on earthquake study cases in Mamasa 2018. Data that is used in this research is data on earthquake cases in Mamasa 2018 that is gained from the Indonesian Agency for Meteorology, Climatology, and Geophysics (BMKG) district IV Makassar, it included data of the time when the earthquake happened, latitude, longitudinal (, depth (< 60 km) and magnitude (≥ 5) SR. The calculation of on peak ground acceleration was conducted by using Donovan and Mc.Guirre methods, whereas to calculate the value of intensity, it is using the Wald method (1999). The result from the calculation of on peak ground acceleration by Donovan is 95.903 gal to 377.094 gals with the intensity VI to VIII MMI. Whereas the calculation result of on peak ground acceleration by Mc.Guirre method is 58.981 gal to 227.39 gals with the intensity V to VII MMI. MMI intensity of the Wald method is obtained by using the PGA value conversation Mc.Guirre method that is closer to the intensity of the result of the macroseismic survey in Mamasa District and relates with the damage that happened on location. The mapping of earthquake intensity based on PGA Mc.Guirre method shows that 3 (three) sub-districts that have an intensity of VII MMI, namely Tawalian Sub-district, Mamasa Sub-district, and Sesean Padang Sub-district. The area is the most vulnerable. Mamasa has low-risk level from the earthquake, although sometimes an earthquake happened until now. This result is supported by a geological map in the Mamasa regions that showed source rock in that area is a type of hard rock that consis of granitic materials.