Attenuation function of earthquake in the subduction zone (megathrust) of the Sunda arc

Abstract

The subduction zone (megathrust) of the Sunda arc is an active area and historically many large destructive earthquakes occur. This zone extends from the Andaman island to the Northwest and from the Banda arc to the west with a length of about ± 3000 km. This subduction zone is produced from a collision between two plates, the Indo-Australian plate and the Southeast Asian plate. Where is the Indo-Australian plate subduct to the bottom of the Southeast Asian plate. The attenuation equation in the subduction zone (megathrust) of the Sunda arc has not been widely developed in Indonesia. So it still refers to the equation of attenuation in subduction zones of other regions. For this reason, attenuation equations are needed in the subduction zone (megathrust) of the Sunda arc and mapping the model of the affected area due to the earthquake in the area. Data used to produce attenuation equation of 71 earthquake events with total data 1236 data. The PGA value used for the calculation of the attenuation equation is derived from the average value of the horizontal component. The method used to produce the attenuation equation is by two-step stratified regression analysis procedure. The physics attenuation equation has calculated the saturation of the acceleration amplitude in the area near the source of the earthquake and has a simple point source characteristic including geometric spreading over medium to long distances. The application of the attenuation equation in the mapping of affected areas due to earthquakes in the subduction zone (megathrust) of the Sunda arc shows results closer to observational data.