Determination Of Earthquake Intensity Based On PGA (Peak Ground Acceleration) Using Multi-Event Earthquake Data

Abstract

Pandeglang Regency is located in the southern coast of Java Island which is adjacent to the megathrust subduction zone. This zone originates from the meeting of the Indo-Australian Plate which is subducted under the Eurasian Plate. So that it can cause frequent earthquakes due to the movement of the plunging plates. Other than that, Pandeglang Regency is also bordered by the Sunda Strait in the western part where the region has Mount Krakatau which has the potential to cause earthquakes due to volcanic eruptions. Therefore, it is necessary to identify the level of earthquake hazard in Pandeglang Regency as a first step in disaster mitigation. Determination of earthquake hazard level in the study area is using the method of scoring the earthquake hazard level parameters based on “Peraturan Menteri Pekerjaan Umum No. 21/PRT/M/2007” and using spatial analysis. These parameters are the physical properties of rocks, slope, seismicity (magnitude, peak ground acceleration, and intensity), and the distance of the region to the fault zone. For the calculation of PGA (Peak Ground Acceleration) using the empirical equation from [10] and calculation of earthquake intensity using the empirical equation from [9]. The level of earthquake hazard is divided into three categories: low hazard level, medium hazard level, and high hazard level. The results of this study indicate that there is no low hazard category in Pandeglang Regency. For the category of medium hazard level has an area of 1719.404 km2 (62.959%). And for the high hazard level category has an area of 1011.573 km2 (37.041%). In almost all sub-districts there are medium and high hazard categories. Subdistricts that does not have medium level of hazard category are Patia and Sindangresmi Sub- district. And sub-districts that does not have high hazard level category are Cibaliung, Cimanuk, Karangtanjung, Koroncong, Mekarjaya, Menes, dan Pandeglang Sub-districts. The largest area in the medium hazard level category is in Cimanggu Sub-district, 344.394 km2. And in the category of high hazard level is also in Cimanggu Sub-district, 396.980 km2.