Determination of the seismicity and peak ground acceleration for Lombok island: an evaluation on tectonic setting

Abstract

Abstract. Lombok Island is located in the Nusatenggara region, which is considered as one of the most active seismic parts of Indonesia. The determination of seismicity is crucial to the island, since Lombok Island is a relatively dense populated small island. Earthquakes that occurred around the island were generated by southern subduction mega-thrust and northern back-arc thrust. Mostly, distributions are concentrated on the north-west and south-east parts of Lombok Island. Probabilistic data analysis of 309 earthquake events during the period of 1973 -2017 results in the Gutenberg-Richter parameters (a and b) of 3.62 and-0.53 indicating medium to high seismic activities. The Joyner-Boore attenuation relation seems to be suitable for seismic characteristics of the island. The reconstruction of tectonic setting indicates that the Benioff zone may develop at the depths of 150 km beneath the island causing horizontal tectonic forces working within the direction of N 171 0 E -N 351 0 E. This could create a strike-slip fault on the crustal basement within the NE -SW direction.

An update to seismic hazard levels and PSHA for Lombok and surrounding islands after earthquakes in 2018

“…For Indonesia, six different attenuation relations have been suggested for three different earthquake sources: subduction, fault and shallow background, and deep background [21]. The Joyner-Boore relation [26] was applied for moderate to shallow sources; whereas, the Boore-Atkinson relation [27] might be applied for a shallow reverse fault, such that located at the back arc of Lombok Island [28].…”

“…A number of empirical attenuation equations have been developed by many researchers for different tectonic characteristics [25]. Two of them, Joyner-Boore [26] and Boore-Atkinson [27], have already been recognised to be suitable for the tectonic characteristics of Indonesia [21], particularly Lombok Island [28].…”

“…According to [44], however, earthquake ground motions are influenced by source, propagation, and site effects. The Joyner-Boore equation indicates the influence of magnitude, distance, and site characterization, which was suitable for Lombok Island [28]. However, the shallow FT was observed to have a dominant influence on current seismic occurrences [12], and the closed distance of the FT to the island seemed to play a crucial role in the ground motion for the island; accordingly, the Boore-Atkinson relation was appropriate for these tectonic sources [21].…”

Mapping of Potential Damages Area in Lombok Island Base on Microtremor Data

“…Figure 1 shows the geological conditions on Lombok Island, Lombok Island that has relatively young rocks (Agustawijaya, Sulistiyono & Elhuda, 2018). The island of Lombok was formed due to the volcanoes produced by the subduction of the Indo-Australian plate with Eurasia.…”

An Investigation of Building Seismic Design Parameters in Mataram City Using Lombok Earthquake 2018 Ground Motion

“…According to Agustawijaya, Sulistyono and Elhuda [17], Lombok is classified as moderate to high seismic activity. Before the strong earthquake of 2018 this study stated that the South Subduction Megathrust and the North Back-Arc Thrust have established the tectonic pattern of Lombok Island as an effect of compression between the Australian continental plate and Eurasia.…”