Rules Index | GM Screen | Player's Guide

Chapter 10: Game Mastering / Environment / Natural Disasters / Earthquakes

Soil Liquefaction

Source Core Rulebook pg. 518 2.0
Liquefaction occurs when granular particles shake to the point where they temporarily lose their solid form and act as liquids. When this happens to soil, it can cause creatures and even whole buildings to sink into the ground. You can use the earthquake spell for more specific rules, though that spell represents only one particular kind of localized quake.