There were a large number of liquid components under ground when lava was moving, and the liquid constrict- ed after cooling, so the lava sunk from the surface.This is a general origin of lava pit.

• 熔岩陷谷（坑）的成因多是由于熔岩隧道塌陷或熔岩底部局部存在大量气液组分，待冷却后体积收缩在重力作用下导致地表的熔岩陷落。