滇西实验场地质构造背景对地震波波速影响的实验研究

本实验用超声地震模型实验模拟观测,滇西地震实验场地质构造格架对地震波波速的影响。模型为1米量级。模型与原型地质的比为1∶470000。实验模型有两块,一块为均匀无构造模型,另一块为有滇西实验场主要地质构造格架模型。实验对两种模型的P波速进行了比较,给出了以模型中心为观测点以及以昆明、中甸、下关和渡口为观测点,模拟震中距为50公里、100公里、150公里和200公里圈上P波波速变化的背景场。这一实验是用物理模型模拟研究复杂地质构造格架对地震波波速影响的首次方法探讨。

AN EXPERIMENTAL STUDY OF INFLUENCE OF GEOLOGICAL STRUCTURE PATTERNS ON SEISMICWAVE VELOCITY IN THE WESTERN YUNNAN TEST SITE

The experiment method of supersonic seismic model is used to do the simulated observation, in which the influence of geological structure on seismic wave velocity in the western Yunnan test site will be considered. The order of magnitude of the model is one meter. The ratio of the model and theactual geological structure is 1 : 470000. There are two blocks of experimental model. One is a nontcctonic uniform block. The other is a tectonic block contaning the main geological structure in the western Yunnan test site. Inexperiment a comparison between P-wave velocity of two blocks has beencarried on. Taking the center of the model and Kunming, Zhongdian, Xiaguan and Dukon as the observational points, and the simulated epicentral distances as 50 km, 100 km and 200 km respectively, we have obtained the background fields of P-wave velocity variations on the various circles. The experiment in terms of physical models has made an study for the influence of geological structure on seismic wave velocity for the first time.