The devastating 7.5 magnitude earthquake that hammered the Indonesian island of Sulawesi caused liquefaction, which is when the ground essentially behaves like a liquid—often occurring during major earthquakes.
Indonesia’s National Disaster Mitigation Agency said that soil liquefaction was reported following the Sept. 28 earthquake, according to The Jakarta Post.
“We observed that such phenomenon had dragged buildings away in several locations, such as in Sigi Biromaru District in Sigi Regency and South Palu District,” agency spokesman Sutopo Purwo Nugroho said, the Post reported.
On social media, videos circulated showing the alleged liquefaction in action. In one jerky clip, trees and buildings (look for the red-roofed building at 25 seconds) are seen essentially sliding on the ground, which appears highly unsettled.
— Jonathan Miller (@millerC4) October 1, 2018
“Indonesian disaster agency says this shows ‘liquefaction’ of ground as earthquake ripples radiate out. Utterly terrifying,” said Channel 4 reporter Jonathan Miller of the video.
Another video appears to show buildings collapsing due to liquefaction. In the clip, buildings can be seen sliding on the ground.
— Sophie Walsh (@sophie_walsh9) September 30, 2018
Advisory. Truly terrifying. And heart-breaking.
— 🚶🏻Curtis S. Chin (@CurtisSChin) September 30, 2018
“This video shows soil liquefaction where pressure from the earthquake combined with saturated sandy soil causes the ground to liquify beneath your feet. Terrifying,” said Sophie Walsh of 9 News.
The U.S. Geological Survey, which records and reports earthquakes around the world, said liquefaction is when “loose sand and silt that is saturated with water can behave like a liquid when shaken by an earthquake.”
“Earthquake waves cause water pressures to increase in the sediment and the sand grains to lose contact with each other, leading the sediment to lose strength and behave like a liquid. The soil can lose its ability to support structures, flow down even very gentle slopes, and erupt to the ground surface to form sand boils. Many of these phenomena are accompanied by settlement of the ground surface—usually in uneven patterns that damage buildings, roads, and pipelines. Three factors are required for liquefaction to occur,” the agency says.
The USGS said that numerous aftershocks hit around where the 7.5 magnitude quake struck, and many were over 5.0 on the Richter scale.
The quake triggered a major tsunami, which according to a previous Epoch Times report, was 20-feet-high in some places. Dramatic video footage (see the top video) show the tsunami slamming the city of Palu after the quake struck.
Death Toll Rises
According to CNN on Oct. 1, the death toll continues to rise. Officials said that so far, 844 people have died.
Indonesian President Joko “Jokowi” Widodo authorized the acceptance of international help, said disaster agency spokesman Sutopo Purwo Nugroho, adding that generators, heavy equipment, and tents were among the items needed. He said the European Union and 10 countries have offered assistance, according to The Associated Press.
“We will send food today, as much as possible with several aircraft,” Widodo told reporters in the capital, Jakarta, adding that a supply of fuel was also set to arrive.
The Associated Press contributed to this report.