Characteristics and Mechanism of the Earthquake-Induced Sand Liquefaction in the January 7, 2025, Dingri M_W7.1 Earthquake

Abstract. Sand liquefaction is a major secondary hazard following strong earthquakes, often causing lateral spreading, surface settlement, and sand volcanoes that lead to significant structural damage and economic losses. This study investigates sand liquefaction phenomena induced by the MW 7.1 Dingri earthquake in Tibet on January 7, 2025, aiming to reveal its spatial distribution and dynamic evolution. Using field surveys, drone imagery, remote sensing interpretation, and drilling data, the study identifies three main liquefaction zones: the southern Pengqu River valley, the area near Dingmu Co Lake, and the southeastern side of Kongmo Co Lake. Groundwater depths in the affected basin ranged from 5.6 to 9.0 meters, closely aligning with local river and lake water levels. Surface damage was dominated by lateral spreading and sand volcanoes. Field evidence and stress analysis suggest a multi-phase evolution: under tectonic stress and gravity, tensile fractures form; seismic vibration triggers liquefaction, with pore fluid and sand being expelled through fractures. On gentle slopes, lateral spreading occurs as surface blocks slide and collide, generating additional fractures through compression, from which sand volcanoes erupt—often aligned linearly. This research offers critical insights into the mechanics of earthquake-induced sand liquefaction on the Tibetan Plateau and provides a foundation for future hazard assessment and mitigation efforts in seismically active, high-altitude regions.