| It is necessary to study the genetic mechanics of strong earthquake and the fluid precursors for the shocks because our knowledge about earthquake is so poor that can not meet the social needs of mitigating disaster of strong earthquakes that frequently occurred in China.The advances of the role of deep-earth fluids in earthquake generation, high temperature and high pressure experiments with rocks and the earthquake prediction based on fluid precursors were reviewed in the dissertation. The compression wave velocities (VP) and conductivity (σ) of gabbro and plagioclasite under high temperature and high pressure were measured with the ultrasonic pulse transmission method and impedance spectra technique, respectively. The original and unloaded samples were chemically measured and analyzed with the electron microprobe instrument and observed under the microscope. The mechanisms of VP and σ variations of the rocks were discussed based on the data of the experiments and analysis. In addition, the origins of gases in the hot springs and seismological activity in West Sichuan Province were mentioned in the viewpoint of stable isotopic geochemistry.VP values of the rocks under high pressure decreased with the increase of temperature. However, VP values of different rocks decreased in the different ways. VP values of the gabbro at the pressure of 1.0 GPa reduced by 4% from the room temperature to 800℃, but reduced severely by 16.4% from 800C to 1100C. VP values of the gabbro at 2.0 GPa reduced 3.6% from room temperature to 850℃, and decreased 4.6% from 850℃ to 1000℃. Otherwise, VP values of plagioclasite at 1.0 GPa decreased by 2.2% from room temperature to 680℃, and decreased sharply by 7.6% from 680℃ to 880℃. The VP value decrease results from mineral dehydration, rock partially-melting under the experiment conditions.The values of conductivity of the rocks at the pressures of 1 and 2 GPa increased with temperature increasing. Under the conditions of 1GP and 410-750℃, the conductivity values of plagioclasite are in the range of 10-7 S/m to 10-5 S/m, and the complex impedance of plagioclasite collected from 12Hz to 105Hz shows only one semicircular impedance arc that represents the conductive mechanism of the grain interior conduction. The experiment data indicated that conductive mechanism of gabbro at temperature less than 680 ℃ was the grain interior conduction, and that the grain boundary conduction occurred at the temperature higher than 680 ℃, which resulted in the increase of conductivity of the rocks.The data of the microscope observation and microprobe analyses argue that no high conductivity grid of interconnection hydrous fluids in the rock was formed during the dehydration, which hints that the formation and evolution of the high conductivity zone in the crust have a close relationship with the amount of the fluids and the interconnection of the fluids as well.The phenomena that the conductivity values of the experiment rocks changed little when the VP values began to decreasing sharply indicated that the grade of minerals dehydration was so lower that the mineral grain boundary and structure of the rock samples changed severely, but did not change the conductive mechanism, which would be the feature of the early stage of a lower-velocity-layer evolution in lithosphere.The stable isotopic geochemical characteristics of helium and carbon of the hot springs indicate that the helium and carbon dioxide in the three earthquake zones of Xianshuihe,Anninghe and Longmenshan in West Sichuan Province have the multiple origins. 3He/4He ratios of the hot springs in Xianshuihe, Longmenshan and Anninghe earthquake zones have the ranges of 0.48-2.59RA, 0.22-1.07 RAand 0.01-0.82 RA, respectively. Higher 3He/4He ratios of the hot springs in the Kangding district demonstrate that the helium is partially derived from the mantle, and the helium of the hot springs in the Aninghe and Longmenshan earthquake zones are predominately derived from the crust with mixing of atmospheric helium. 13C values of carbo...
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