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本文测定了云南省电信传输地震台网中14个台站的远震 P 波走时残差。所用地震共235个,分布在震中方位角-80°至190°之间,共得走时读数约1600个。台站平均残差在0.49～1.18秒间变化,台网区域的总平均残差值为0.81秒。残差随方位角的变化大,P 波通过红河断裂和剑川—丽江裂断东部地区要比通过小江断裂东部地区早到0.70秒,而通过小江断裂西部地区要比通过红河断裂和剑川—丽江断裂西部地区早到0.74秒。滇中块体的地壳和上地幔比滇东和滇西块体有更高的 P 波速度。高速块体与康滇古陆区域对应,剑川—丽江断裂是扬子准地台西端的北西边界。由此推论,以剑川—丽江断裂为界,康滇菱形块体深处南部要比北部稳定,块体作为整体的运动主要局限于地壳某一深度之上。给出了具有方位角影响的台站 P 波走时校正参数。倍角方位角项 Cos2■的相角与由震源机制导出的地壳中的主应力方向对应良好。
In this paper, the teleseismic P-wave traveltime residuals of 14 stations in Yunnan Telecom Transmission Seismic Network are measured. A total of 235 earthquakes were used, distributed over the epicenter azimuths of -80 ° to 190 ° with a total of about 1600 readings. The average station residual variation varied from 0.49 to 1.18 seconds, and the total average residual value of the station area was 0.81 seconds. The residual variation with azimuthal angle is larger. The P wave passes through the Red River fault and the eastern part of the Jianchuan-Lijiang rift than the eastern part of the Xiaojiang rift through 0.70 seconds, whereas the western part of the Xiaojiang rift passes the Red River fault and the Jianchuan- The western part of the Lijiang fault as early as 0.74 seconds. The crust and upper mantle of the Central Yunnan block have higher P-wave velocities than the eastern Yunnan and western Yunnan blocks. The high-speed blocks correspond to the Kang-Dian ancient land area, and the Jianchuan-Lijiang fault is the northwestern boundary of the western end of the Yangtze Platform. It is deduced that the southern part of the Kangbian diamond block is more stable than the northern part in the Jianchuan-Lijiang fault, and the movement of the block as a whole is mainly confined to a certain depth above the crust. The station P wave travel time correction parameters with azimuth influence are given. The phase angle of the cosine angle term Cos2 ■ corresponds well to the principal stress direction in the crust derived by the focal mechanism.