December 18, 2023 Earthquake: Jishishan, Gansu Province, China

Reference #13456:

Tectonic Summary

The December 18, 2023, M5.9 earthquake in north-central China occurred as a result of reverse faulting at shallow depth. The earthquake occurred on either a north-striking, steeply dipping, reverse fault or a south-southeast striking, shallowing-dipping, reverse fault. The region where the December 18th earthquake occurred is an intraplate (i.e., not at a plate boundary) region located on the northern margin of the Tibetan Plateau. The Tibetan Plateau is a high topographic region north of the Himalaya Mountains that developed in response to ongoing collision between the India and Eurasia plates.

The Tibetan Plateau is tectonically active, and earthquakes are common throughout the region. Within 250 kilometers of today's event, 23 M5.5 and larger earthquakes have occurred since 1900. The largest of these is a M7.7 earthquake in May 1927, to the north that resulted in roughly 40,000 fatalities. The 1927 earthquake resulted in extreme damage in the Gulan-Wuwei area and resulted in damaging landslides. In April 1990, a M6.5 earthquake, immediately preceded by a M6.3 foreshock and followed by a M6.3 aftershock, led to at least 126 fatalities and extensive shaking damage and landslides. Earthquake-related losses in China are common, even for moderate magnitude earthquakes, owing to the proximity of large population centers to shaking, the prevalence of structures that are vulnerable to earthquake shaking, and the occurrence of landslides in steep topography.

In Gansu, more than 207,000 homes were wrecked and nearly 15,000 collapsed, affecting more than 145,000 people. [As of 20 Dec]. The death toll from the 6.2-magnitude earthquake that jolted northwest China has risen to 117 in Gansu Province, bringing the total to 148 in Gansu and Qinghai provinces, local authorities said Friday [22 Dec]. As of 8 a.m. Friday, the earthquake had injured 781 people in Gansu, according to the provincial earthquake relief headquarters. [As of 20 Dec] In Qinghai 186 injured. (reference #13674, #13675)

The 6.2-magnitude earthquake that jolted northwest China on Dec. 18 has in total killed 151 people in Gansu and Qinghai provinces as of Sunday. The death toll rose to 34 in Qinghai on Sunday morning, as the last two people who were previously unaccounted for after the earthquake were found dead, according to the provincial earthquake relief headquarters. The earthquake has also killed 117 people in Gansu, local authorities said on Dec. 22 (reference #13681, #13686)

2+ billion dollars in economic losses (reference #13724, #13727)