Water becomes a solid, a liquid and gas corresponding to the change in temperature and the pressure. This is known as three condition of the water. Those relations are shown like Fig.1.

Water becomes super-critical condition when it exceeds heat water condition in the underground of the high temperature and the high pressure.

When temperature rises more, water dissociates in oxygen gas and the hydrogen gas. The degree of the dissociation changes due to temperature and pressure and the existence of the catalyst material.

Generally, the degree of the dissociation rises when temperature is high then when pressure is poor. That degree rises when silicic acid compound exists. The line which the degree of the dissociation is the same as is supposed to be shown as the figure. Contents in the circle of the figure are explained with Fig..2 in detail.

Water partly dissociates when it is moved from the area whose level of a dissociation is low to the high area. Surrounding temperature decreases because a dissociation response is an endothermic reaction. The detonating gas which collected inside the magma chamber doesn't ignite soon.

But, low temperature areas decrease because there is a movement of the heat from the circumference gradually. Then, when it reaches ignition temperature, a detonating gas ignites, and explodes.

This is a seismic occurrence cause. An explosion is a consolidation response, and heat is radiated. It is returned in the water which became stable again, and temperature rises. At this time, because there is an energy loss, it isn't returned perfectly in the previous heat pressure relations. The earth gets cold for that because it is consumed as an earthquake energy. When a change in a level of a dissociation is drastic, large quantities of dissociated water (detonating gas) explodes, and becomes a big earthquake.

As for the tunnel construction in the volcanic zone and the geothermal electric power plant, we must take a balance of the heat pressure into consideration fully. If enough examination isn't given, it has the danger which causes an earthquake artificially.

The earthquake which occurred in the construction accident in the Abou-tunnel （nagano)and the neighborhood of Matsukawa(iwate) geothermal electric power plant might be an artificial earthquake.

It is estimated that the phenomenon of "YAMAHANE" which happens in the coal mine is the explosion phenomenon of the detonating gas, too. A collier with the experience knows that vapor occurs as much as not to see the bottom from the waist any more before YAMAHANE occurs.

Two figures tell more things. When underground pressure is reduced rapidly in the spot which mines petroleum and natural gas, a level of a dissociation of the bottom from a position of mining is increased. This has the danger to induce an earthquake. And, substitution water is sent to the gap after mining, and a pressure balance is kept by mining in recent years to mine all efficiently. This has the effect which restrains a dissociation as a result. Because this way of mining it wasn't taken, an artificial earthquake might occur in the age when Sakhain earthquake (1995) and Niigata Kitakanbara earthquake (1995) happened.

Mr. Dai fon is afraid that it induced Hanshin big earthquake to make a big hollow in the underground of the town of Kobe.

Research on the stability of the dissociation layer which is inside the underground is necessary. It is dangerous to dig the big depth underground space easily without doing this research.