A series of earthquakes that have rocked the eastern coast of Chiba Prefecture and related areas over the past week are believed to be related to a phenomenon known as "slow slip" of tectonic plates. The phenomenon has prompted a government commission to warn of the possibility of additional "strong tremors" in the coming days.
Three earthquakes with an intensity of 4 on Japan's seismic intensity scale, as well as four with an intensity of 3, have occurred since Thursday, including a magnitude 5.2 quake on Friday.
These earthquakes are likely caused by slow slip between the Philippine marine plate and the continental plate off the coast of Chiba, based on satellite observation data from the Geospatial Information Service of Japan.
Unlike normal earthquakes, which are characterized by rapid slip, slow slip can cause minor surface shaking. This phenomenon occurs when stresses build up to limits, as in normal earthquakes, but slip is slow due to fault properties, with a repetitive cycle of snap and slow slip.
