Possible soil thermal response to seismic activities in Alborz region (Iran)

Abstract. In this investigation, relations between the ground's thermal properties and 70 earthquakes with a magnitude >4 Richter in the Alborz region during a period of 12 years (1992 to 2004) were studied. Typical changes of ground temperature, 0.4 °C; thermal diffusivity, 0.028 m² s⁻¹×10⁻⁶ and ground heat flux take place a few hours prior to the earthquakes. The values of thermal diffusivity depend on the ground moisture content, which may change during seismic activities. The analysis of ground heat flux from the epicentre and it's surrounding regions show some anomalous behavior before the earthquakes but with different signs in the areas close to the sea and far away from the sea.

The changes of the ground's thermal properties prior to the earthquakes in the Alborz region are attributed to the increase in seismic activities in the epicentre and it's surrounding regions. The anomalous behavior in the ground thermal properties shows great potential in providing early warning of imminent earthquake.