October 9, 2018 – The tsunami-driven floodwater has receded from Indonesia’s Sulawesi island, but the slow-motion disaster continues. The major earthquake last week and subsequent loosening of the soil has spurred landslides and even liquified the ground around the coastal city of Palu.
Proses likuifaksi tanah di Kota Palu hasil rekaman citra Satelit WorldView resolusi pixel 0.5 meter. Rumah dan bangunan terseret oleh lumpur yang muncul akibat gempa dan menenggelamkannya. Tim SAR terus bekerja melakukan evakuasi di daerah ini. Korban terus ditemukan. pic.twitter.com/G3Ki40tdmA
— Sutopo Purwo Nugroho (@Sutopo_PN) October 5, 2018
Satellites hovering above the Earth have observed it all and sent back shocking imagery to teams on the ground working on recovery efforts. Among the wildest scenes was one shared by Sutopo Purwo Nugroho, a member of Indonesian National Board for Disaster Management. At first, it’s easy to think you’re staring at a magic eye illusion, but no. The imagery from Digital Globe’s WorldView blends before and after imagery to show how an entire chunk of countryside near Palu liquified and slid downslope.
Liquefaction is a major concern in earthquake-prone areas that aren’t sitting on firm bedrock, especially if the soil is saturated whether by rain or a high water table. The shaking of an earthquake can cause loose, sandy soil to becoming semi-fluid. It can also increase water pressure in soil, with similar results.
The satellite footage provides a clinical look at how liquefaction can play out, but videos on the ground have shown the process on a more human scale. In one, houses collapse and ride the suddenly fluid soil like it’s a people mover for multi-story buildings.
In another, an entire radio or cell tower slides by. The video ends with a raging caldron of liquid mud racing toward the camera.
As death toll from #IndonesiaEarthQuake & tsunami reaches 1200, a closer look at landslide & liquefaction of the village Petobo south of #Palu, Sulawesi, Indonesia 🇮🇩#PrayForPalu #PrayForDonggala https://t.co/gvHQDj7PZf @sadbumblebee reports pic.twitter.com/cyeqiRnWjj
— 🚶🏻Curtis S. Chin (@CurtisSChin) October 1, 2018