抄録
In situ X-ray observation using Drickamer type high pressure apparatus and its application to geophysics are discussed in detail. At first, characteristics of Drickamer apparatus are introduced by comparing with diamond anvil cell and multi anvil apparatus. Then, two topics are discussed as its applications to geophysical problems: One is the mechanism of deep-focus earthquakes and the other is the phase relation of iron which thought to be dominant component of the Earth's inner core. Nature of deep-focus earthquakes has been enigmatic. Two models describing the mechanism of deep earthquakes are proposed recently based on high pressure experiments and seismological measurements of the structure of subduction zone. These two models, frictional instability caused by pore water pressure and transformational faulting, are briefly introduced, and discussed in relation to differential stress measured by the Drickamer apparatus. Recently, the existence of two new phases of iron is proposed. One is a high temperature phase with dhcp structure, which appears at pressures of above 30GPa. The other is a very high pressure and temperature phase above 200GPa and 4000K with bcc structure which is proposed theoretically. Whether the former new phases exist or not is discussed together with X-ray and electrical resistance data obtained by the Drickamer apparatus.
