祁连山构造带红外测距观测揭示的应变强度时空演变特征

利用截止2007年最新的、跨祁连山构造带红外测距观测资料，结合区域GPS观测所得形变背景，获取跨断层水平应变强度时空演变特征，分析其与2002年玉门Ms5．9级、2003年民乐Ms6．1．级等地震孕育一发生过程的关系。结果表明：①震前数月至1年左右，震中所在断层段（或整个构造带）应变加速或相对其它断层段显著，压性为主；其内一定数量场地最大剪应变强度明显“增强”或面应变强度“压性增强”（至绝对值2．0左右及以上），震后减弱或呈现张性转折。②2004年下半年以来祁连山构造带总体恢复压性变化为主的应力场状态，反映一定程度应力应变积累特性；2007年构造带西段压性应变明显增强。

TIME-SPACE EVOLUTION CHARACTERISTICS OF STRAIN INTENSITY OF QILIANSHAN FAULT ZONE REFLECTED BY INFRARED RANGE-MEASURE

Using the new observational data of infrared range- measure crossing Qilianshan fault zone up to 2007, combined with deformation background observed by GPS, the time - space evolution characteristics of strain intensity and their relationship with Yumen Ms5.9 earthquake in 2002 and Minle Ms6. 1 earthquake in 2003 were researched. It concluded that： （1） From several months to about one year before the earthquakes, the segment of fault （or entire fault zone） where the earthquake took place displayed strain accelerating or higher than other segments, major in compression, some sites over there reflected intensity of the maximal shear strain or compressional superficial strain increasing （ its absolute value was about or larger than 2.0 ） , after the earthquake, it decreased or showed tensional turning; （2）Since the latter half of 2004, the Qilianshan fault zone had resumed the status of stress field mainly reflecting compression, presented features of accumulation of strain and stress to a certain degree. In 2007, the compressional strain of the western segment of this fault zone strengthened obviously.