By and large, tectonic activity raises our archipelago as we’re on the receiving side of several subductive plates. The process is not uniform, though, as subsidence may create localized cavities. My house sits atop a minor fault, and I’ve watched as its western side has subsided and noticed subsidence on area roads. This can be dangerous for drivers and pedestrians as large holes can appear quite suddenly.
Kumanichi reports that the two companies the Transportation Ministry had hired to inspect roads had done a lousy job so has hired a third company which has created an ingenious way to detect these cavities. First, a vehicle equipped with ground-penetrating radar (chichyuu reda, 地中レーダー) will sweep an area; if anomalies are found, a crew will conduct a more thorough investigation and repair the damage before the road falls through. Look for these around town. (Note that the radar mark resembles the poo poo emoji.) - William
