Abstract:Analysis and research on the fault-gas precursorg phenomena before the Jingtai M6.2 Earthquake are made based on a lot of data. Tha results show that the gases Rn and CO₂ at Guyuan site on the earthquake-generating fault and gases Hg and H₂ at the nearest Gulang site from seismic center have very distinctive medium-long term,short term and impending earthquake precursors. The extent of this earthquake an0maly is up to more than 500 km,associated with 13 kinds and/or times of gas anomalies,in which Hg and H₂have the most informations. Kesearches also suggest that the sudden variation of He and Ne is the expression of increasing activity of the fault,and is medium term precursor of the present strong earenguake,because He and Ne are product of nuclear fusion in depth of the earfh.

Abstract:Based on the research of loess being of the property of seismic subsidence, this paper pointed out a type of particular disaster that people has not pay attention to, yet, which is that serious accidents of ground losing efficacy will happen in cities on loess sites under the effct of earthquakes. Because of seimic subidence occurring suddenly and distributing inhomogenously generally,the seismic damage of common industrial civil buildings become more serious under the effct of shaking and residual deformation of ground together. Usual phenomena of the seismic damage are cracking, slopping and Collapsing of buildings. To take Lanzhou as an example, the disaster induced by loess seismic subsidence are proved to be serious disaster which can not be underestimated. The engineering field and the department of city construction Should think highly of it, studying the effect of loess seismic subsidence on buildings,taking appropriate prevention measures and lessening or avoiding the loss caused by the disaster of seismic subsidence.