Shortly after a magnitude-6.2 earthquake jolted Jishishan County in northwest China's Gansu Province on Monday night, thick mud, up to three meters high, rolled into Minhe County in neighboring Qinghai Province.
Houses and roads in Jintian and Caotan villages were covered by heavy mud, with some villagers still missing. The Qinghai provincial rescue team organized cleanup and relief work immediately after the incident.
The mudslide completely buried the roads leading into Caotan Village and damaged some houses. The earthquake also broke communications cables, resulting in a power outage. At the entrance to Jintian Village, a road that used to enter the village, a few houses and an empty lot are now covered with mud. Currently, the excavators are running continuously to do digging and clearing work.
The resettlement of villagers is also proceeding in an orderly manner. Families of the missing, accompanied by other family members and government workers, are living in tents closest to the rescue site and waiting for news of their loved ones.
Aerial view shows houses covered by the thick mud in Minhe County in northwest China's Qinghai Province, December 19, 2023. /CMG
Origin of the mud
There is a ditch next to the affected villages, and it only has little water during the summer and rainy seasons. The water table is relatively high, so the earthquake easily turned all the mud under the ground up, and the mud slid down from the north through the ditch, said Qi Fenyong, an official of Minhe County.
"The ditch is wide in the upper part and narrow in the lower part. At a fork in the road not far from Jintian Village, the width of the road changed from more than 20 meters wide to three or four meters. As the road narrows, mud can no longer pass through, and it builds up and spills over into the villages," he said.
Han Yanyan, a senior engineer at the China Earthquake Networks Center, explains the reasons behind this phenomenon.
"The earthquake will intensely liquefy underground sediment, producing a slurry that eventually ruptured the ground and spewed out, creating the landslide," she said.
This phenomenon is related to the water content of the underground aquifer and the degree of extrusion. "More mud surge does not necessarily mean that a major earthquake is likely to follow, and no mud does not mean it's safe. The appearance of mud is not related to whether there will be an earthquake. It's just a natural phenomenon," Han added.