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一、典型震例我国地震台网近三十年来积累了二百多万张地震图;其中约十余万张图属于极远震记录.这些记录无不带有地核的信息.这对研究核内的速度分布和分层结构以及地核物质的物理性质,是十分珍贵的资料和依据.长期以来,我们对极远震记录的分析和解释,都是依据J-B走时表进行的;因此,在所汇编的地震观测报告中,对PKP波只报导了AB和DEF这两个分枝,亦即相应于外核的折射波PKP_2和内核的折射波PKIKP(或PKP_1).这一类观测报告,忽略了存在于125“< △<157°间,且当△<146°时以PKIKP波的前驱者出现在记录图上的PKHKP波.
First, a typical earthquake cases China’s seismic network in the past three decades has accumulated more than two million seismic maps; of which about more than ten million images belong to the extreme earthquake records without these records with the core information .This study of nuclear Within the velocity distribution and stratification structure and the physical properties of the Earth’s nuclear matter is a very valuable information and basis for a long time, our analysis and interpretation of the extreme earthquake records, are based on JB walking schedule; therefore, in the In the seismological report compiled, only two branches of AB and DEF were reported for PKP waves, namely the refracted wave PKP_2 corresponding to the outer core and the refracted wave PKIKP (or PKP_1) of the inner core. This kind of observation report, Neglecting PKHKP waves that occur at 125 "<Δ <157 ° and appear on the chart as precursors of PKIKP waves when Δ <146 °.