DAS
https://blogs.egu.eu/divisions/sm/2023/12/02/what-is-das/
The Ukranian battlefield is a massive high resolution DAS survey waiting? to happen, the drones laying down the fiber optic cable in my opinion are the nice "two birds with one stone" benefit.
Those fields crisscrossed with fiber optic cables, well they are from a signal analysis standpoint a spiders web in that any disturbance in the microtremor wavefield is highly resolvable in terms of location and nature. Footsteps, a drone clandestinely dropping an an antitank mine, large weapon fire etc...
If you could access fiber optic cables in the vicinity of an artillery target you could determine fairly easily where exactly it fell algorithmically to a high degree of confidence. Fiber optic cables laid down for unrelated infrastructure purposes even.
I am sure I am not the first idiot to realize this shrugs the idea aggressively jumps out at you if you understand the science.
This is ambient seismology not necessarily active though a howitizer would make a mighty fine source impulse.