Satellites or ground-based observation.

Geologists have used the latter for many decades. Monitors upslope of at-risk glaciers, solar/battery powered, and communicating by radio (or Internet / satellite links) could be part of this.

See for example the extensive seismic monitoring of California's San Andreas Fault, particularly at Parkfield and through the Carrizo Plain / CA Hwy 25.

<https://earthquake.usgs.gov/learn/parkfield/safod_pbo.php>

<https://en.wikipedia.org/wiki/Carrizo_Plain>

<https://en.wikipedia.org/wiki/California_State_Route_25>

(Different tech, obviously, but in situ ground-based sensors which share some similarities.)

Ground based field instrumentation on specific potential threats has the advantages of being up close and always on target whereas sat observation is distant and intermittent.

Multiple sat observations a day is great, obviously, but sudden collapses / changes often won't get flagged for seven or eight hours after the event.