Coseismic spring flow changes associated with the 1995 Kobe Earthquake

Abstract

Flow rate in many springs increased rapidly after the 1995 Kobe earthquake, which is likely caused by permeability enhancement. The flow rates at nine springs on Awaji Island near Kobe from 1995 to 1998 reveals that the enhancement of flow rate gradually decreased exponentially within two years. The enhanced hydraulic diffusivity of the aquifer is estimated at from 130 to 2,300 cm²/s by using a very simple diffusional model. About seven‐fold increase in spring flow rate and permeability due to the earthquake is inferred from the analysis.