Unstable steam-water convection as possible trigger to earthquakes

Abstract

Convection occurs when two water reservoirs, the overlying and the underlying, are connected by a narrow channel and the fluid in the lower reservoir is heated to the stage of phase transition into steam. The laboratory study of the properties of unstable steam-water convection showed that under favourable P-T conditions the convection can be the triggering mechanism of seismicity. This type of convection causes a sudden fall of pressure in the lower reservoir and in the connecting channel, the impulsive mechanical disturbances, and cyclicity. The point of initiation of this phenomenon can be located at a depth of 5–7 km from the earth’s surface with subsequent propagation of the process of instability to larger and smaller depths. This model of the natural terrestrial conditions can account for the earthquake cyclicity in the same focal zones, the rise of temperature and of the level of ground waters during earthquakes, the enhancement of seismicity while filling the water storage basins, the effect of “floating up” of hypocenters of aftershocks and the greater intervals between them.