Table 1 Occurrence of geophysical, hydrological, and geochemical precursors before the Kobe earthquake (17 January 1995).
From: Radon degassing triggered by tidal loading before an earthquake
Component | Location | Occurrence times | Phenomena | References |
|---|---|---|---|---|
Intermediate-term precursor | ||||
Elevation | RTK | 1991 to 1994 | Elevation uplifted | |
Crustal strain | RTK | 1992 to 1994 | Amplitude and phase of O1 constituent changed | |
RTR | 1991 to 1994 | Contraction decreased | ||
ABU, AMA, DON | 1990 to late 1992 | N–S oriented contraction increased | ||
Seismicity | RAFZ | From 1990 | Seismic quiescence occurred | |
34–36° N; 134–136° E | 1991 to 1993 From 1994 | b value increased b value decreased | ||
Off Okayama | 1991 to 1993 | Background seismicity decreased | 40a | |
Atmospheric radon | KPU | 1990 to 1994 | Response to tide (K1) occurred | This study |
Short-term precursor | ||||
Crustal strain | RTK | From Sep. 1994 | Crustal strain changed to extension | |
ABU, AMA, DON | From mid-1994 | N–S oriented strain changed to extension | ||
Groundwater discharge | RTK | From Nov. 1994 | Discharge rate increased with an intermittent peak | |
Atmospheric radon | KPU | From Nov. 1994 | Concentration increased above the normal level | |
Groundwater chloride ion | Rokko | From Aug. 1994 | Concentration increased with a peak occurring after the mainshock | |
Groundwater radon | Nishinomiyab | From Oct. 1994 to 9 Jan. 1995 | Concentration increased with intermittent peaks | |
