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.)