# Spatio-Temporal Distribution of Ground Deformation Due to 2018 Lombok Earthquake Series
## 1 Introduction  
DInSAR (Differential Interferometric Synthetic Aperture Radar) is a satellite-based approach in Geographic Information Science that allows measuring of deformation on earthquake-impacted areas [1, 2, 3, 4] in the last decades [5, 6]. Integrating DinSAR and GIS would improve the studies related to topographic changes using conventional technique [7, 8, 9, 10] and direct measurement [11, 12, 13, 14, 15]. DInSAR can be created from active remote sensing that transmits radio waves with vertical and horizontal polarization to the earth's surface and then receives it back to form radar images. The main principle of DInSAR is to calculate the interference between two radar images and measure the displacement value between them. Most of the studies extensively used the DinSAR technique to analyze a single earthquakeevent, such as in Chile [16; 17], New Zealand [18], Iran-Iraq [19; 20; 21], US [22], Cyprus [23], Azerbaijan [24], Italy [25], and Mexico [26]. Although, the occurrence of earthquake series should be studied as well. Sentinel 1 allows to measure the displacement due to earthquake [2; 3; 5]. It was launched in 2014 as a continuation of the European Space Agencies' previous SAR satellite channels ERS and ENVISAT. Its mission is dedicated to providing high-resolution remote sensing image data to support observation of environmental changes on earth's surface to ensure sustainable economic growth. Sentinel 1 operates C-band sensor (5.405 GHz) installed on two satellite constellations (Sentinel-1A and Sentinel-1B) with repeat cycles every six days. Sentinel 1 is working on both single polarization (HH and VV) and double polarization (VV + VH and HH + HV). This outstanding specification is then fit into the data requirement in order to monitor ground displacement due to earthquake series. Lombok Island in Indonesia experienced a massive earthquake series in 2018 (Figure 1). This island is between Back Arc Thrust (Figure 2) in the north and active subduction zone of the Java trench in the south due to the convergence movement of the Eurasian and Indo-Australian plates. Four tertiary formations from early Miocene to late Miocene is located in the southern part of the island where most of the lineaments can be found. These geological formations include Kawangan formation (alternating quartz sandstone, claystone, and breccia), Pengulung formation (breccia, lava, tuff with lenses of limestone), Ekas Formation (Limestone/calcarenite), as well as Dacite and Basalt intrusive rocks [27]. Four younger formations from Pleistocene are located in the middle of the island. They consist of Kalipalung formation (alternating calcareous breccia and lava), Selayar Formation (tufaceous sandstone, tufaceous sandstone with thin carbon interalations), Kalibabak formation (breccia and lava) and Lebopiko formation (pumicous tuff, lahar breccia and lava). The youngest formations in the northern part of the island are from Holocene. At low altitude, there is Alluvium (pebble, granule, sand, clay, and coral fragments), while at high there is undifferentiated volcanic rocks originated from Mount Pusuk-Nangi and from Mount Rinjani. The latter is the present name of Samalas volcano which experienced caldera-forming eruption in 1257 AD, producing 40 km\({}^{3}\) volcanic materials including deposits in both the Arctic and Antarctic ice cores [28]. This volcano is located next to Back Arc Thrust in the north of the island. An interesting finding related to the location of the Back Arc Thrust is that its location is actually much closer to the shore than was expected from the previous geological map [1] (Figure 2). Figure 1: Epicentres of major earthquakes in Lombok Island. This geologic setting leads to continuous exposure of this island to earthquakes. Recent shallow and great magnitude of earthquake series occurred in 2018 next to the Back Arc Thrust. The first 6.4 Mw foreshock hit on 29 July 2018.