Correct

坍陷

/ tān xiàn / 
Strokes

Example

As a Verb

sink; subside; cave in; settle

1
Suìdào
隧道
tānxiàn
坍陷
le
了
  
。

The tunnel caved in.

2
Dìjī
地基
tānxiàn
坍陷
le
了
  
。

The foundations have sunk/subsided.