论文部分内容阅读
In regards to the earthquakes recording M≥5.0 that occurred in middle northern part of the Qinghai-Xizang (Tibet) Block from 1970～2003, in this study we describe the temporal and spatial centralization features of the weak earthquakes and the enhancement and anomalous quiescence of their seismic activity before main shocks through 4 parameters, which are basically not correlated: earthquake time centralization degree parameter C_t, earthquake space centralization degree parameter C_d, η value and weak earthquake frequency and so on. On the basis of calculation results, it has been seen that before earthquakes with M≥5.0 took place in the middle northern part of the Qinghai-Xizang (Tibet) Block, the frequency of weak earthquakes often shows ascent and drop, their strength shows an obvious enhancement and the centralization distribution with time and space is evident.
In regards to the earthquakes recording M≥5.0 that occurred in middle northern part of the Qinghai-Xizang (Tibet) Block from 1970 ~ 2003, in this study we describe the temporal and spatial centralization features of the weak earthquakes and the enhancement and anomalous quiescence of their seismic activity before main shocks through 4 parameters, which are basically not correlated: earthquake time centralization degree parameter C_t, earthquake space centralization degree parameter C_d, η value and weak earthquake frequency and so on. On the basis of calculation results, it has been seen that before earthquakes with M ≥5.0 took place in the middle northern part of the Qinghai-Xizang (Tibet) Block, the frequency of weak earthquakes often shows ascent and drop, their strength shows an obvious enhancement and the centralization distribution with time and space is evident.