Liquefied Soils
Soil liquefaction flooding into Palu Bay, Indonesia, 10-1-2018 (credit: ESA & Landsat-8)
Soil liquefaction occurs when the physical properties of soils is impacted by an earthquake. The phenomenon has historically caused major damages around the world. The process happens when soils are super-saturated by water that increases the pressure on individual soil particles. The saturation affects their rigidity and ability to stick together. During an earthquake, the shaking pressure increases to where the soil simply liquefies. A recent example of this dramatic affect happened on the Indonesian island of Sulawesi where an earthquake measuring 7.5 on the Ricter Scale hit the island. Particularly hard hit was the regional city of Palu where an entire mountainside liquefied, carrying many of town's houses, shops, and inhabitants into the nearby bay.
The environmental monitoring satellite Landsat-8, operated by NASA and the US Geological Service, captured a series of photographs during the liquid mud-flow allowing the process to be animated. It doesn't make for a 'pretty picture'.
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