SAR and Optical Data Comparison for Detecting Co-Seismic Slip and Induced Phenomena during the 2018 Mw 7.5 Sulawesi Earthquake.

Marco Polcari,Salvatore Stramondo,Christian Bignami,Cristiano Tolomei

doi:10.3390/s19183976

Marco Polcari, Salvatore Stramondo + Show 2 more

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https://doi.org/10.3390/s19183976

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Abstract

We use both Synthetic Aperture Radar (SAR) and Optical data to constrain the co-seismic ground deformation produced by the 2018 Mw 7.5 Sulawesi earthquake. We exploit data processing techniques mainly based on pixel cross-correlation approach, applied to Synthetic Aperture Radar (SAR) and optical images to estimate the North–South (NS) displacement component. This component is the most significant because of the NNW–SSE geometry of the fault responsible for the seismic event, i.e., the Palu-Koro fault, characterized by a strike-slip faulting mechanism. Our results show a good agreement between the different data allowing to clearly identify the surface rupture due to the fault slip. Moreover, we use SAR and optical intensity images to investigate several secondary phenomena generated by the seismic event such as tsunami, landslides, and coastal retreat. Finally, we discuss differences between SAR and optical outcomes showing strengths and disadvantages of each one according to the investigated phenomenon.

Highlights

On 28 September 2018, a large Mw 7.5 earthquake struck the Sulawesi island, Indonesia, producing big tsunamis with waves higher than 2 m, landslides, flooding, and soil liquefaction effects which severely affected Palu Bay [1,2,3,4]
Most of damages were observed in the urban area of Palu and in the nearby villages where the seismic event and the following induced phenomena destroyed hundreds of buildings causing more than 2000 casualties and 4000 injuries
The results in terms of co-seismic ground displacement retrieved by Synthetic Aperture Radar (SAR) and optical data are consistent each other both showing a significant co-seismic slip mostly characterized by left-lateral strike-slip component consistently with the Palu-Koro faulting mechanism

Summary

Introduction

On 28 September 2018, a large Mw 7.5 earthquake struck the Sulawesi island, Indonesia, producing big tsunamis with waves higher than 2 m, landslides, flooding, and soil liquefaction effects which severely affected Palu Bay [1,2,3,4]. Most of damages were observed in the urban area of Palu and in the nearby villages where the seismic event and the following induced phenomena destroyed hundreds of buildings causing more than 2000 casualties and 4000 injuries. Sulawesi is located west of the Maluku Islands and east of Borneo, along a junction between three major plates, i.e., the Australian, Philippine, and Sunda plates. It is one of the four Greater Sunda Islands within the Malay Archipelago, apart from Java, Sumatra, and Borneo islands. Its landmass is formed by four peninsulas, which are the Minahasa Peninsula, the East Peninsula, the South Peninsula, and the South-East Peninsula and divided into six districts, i.e., North Sulawesi, Gorontalo, Central Sulawesi, West Sulawesi, South

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