This is a major hazard in coastal areas or river basins with sandy, loose soil. During an earthquake, the vibrating motion compacts the soil particles, pushing the water trapped between them upward. This pore-water pressure becomes high enough to support the weight of the soil, turning solid ground into a slurry. This was famously seen in the 1964 Niigata earthquake and the 2011 Christchurch quake. Once the shaking stops, the water drains and the soil settles, often leaving “sand volcanoes” on the surface as evidence of the high-pressure water escape.