4438 () posted 259 days ago by stevejobs871 259 days ago by stevejobs871 +4438 / -0 232 comments share 232 comments share save hide report block hide child comments Comments (232) sorted by: top new old worst You're viewing a single comment thread. View all comments, or full comment thread. ▲ 9 ▼ – ModernKnight 9 points 259 days ago +9 / -0 Seismic sensors are fantastic tools for detecting when and where tunnels are being dug. If they are sensitive enough they will even tell when there is foot traffic moving through established, even concrete floored, tunnels. They're fantastic. permalink save report block reply ▲ 3 ▼ – deleted 3 points 258 days ago +3 / -0
Seismic sensors are fantastic tools for detecting when and where tunnels are being dug. If they are sensitive enough they will even tell when there is foot traffic moving through established, even concrete floored, tunnels. They're fantastic.