On the relation of moderate-short term anomaly of earth resistivity to earthquake

1 139 moderate-short term anomalies of earth resistivity before 196 earthquakes with magnitude M _S=3.2–7.9 (the M _S≥4.0 event accounting for 94%) are studied in this paper, the results are concluded as following: 1 There is a nonlinear function between anomaly time and magnitude of earthquake. For earthquakes M _S≤5.0 or so anomaly time linearly increases quickly with magnitude increasing; for earthquakes 5.0<M _S<6.5 the increasing rate of the time with magnitude increasing gradually become small; for earthquakes M _S≥6.5 the rate is quite small. 2 There is a nonlinear exponential function between anomaly amplitude and magnitude. For earthquakes M _S≤5.0 or so the amplitude increases slowly with the increasing of magnitude; for earthquakes 5.0<M _S<6.5 the increasing of the amplitude is gradually accelerated with magnitude increasing; for earthquakes M _S≥6.5 the increasing is accelerated quickly with magnitude increasing. The two non-linear functions mentioned above are interpreted qualitatively, and the mechanism of this phenomenon is discussed based on the model of rheomorphic medium. Foundation item: Sub-project “95-04-01-01-09” from China Seismological Bureau Contribution No. LC2000026, Lanzhou Institute of Seismology, China Seismological Bureau.