surface subsidence
the motion of a surface (usually, the Earth's surface) as it shifts downward relative to a datum such as sea-level
en-US/ˈsɝfɪs səbˈsaɪdəns/
en-GB/ˈsɜːfɪs səbˈsaɪdns/
the motion of a surface (usually, the Earth's surface) as it shifts downward relative to a datum such as sea-level