ESTIMATION OF SHALLOW S-WAVE VELOCITY STRUCTUREBY USING HIGH PRECISION SURFACE WAVE PROSPECTING ANDMICROTREMOR SURVEY METHOD

摘要

The high precision surface wave prospecting method is a technique in which we observe surface wavesgenerated by artificial shock with one-dimension array of seismometers and estimate S-wave velocitystructures by means of inversion of the phase velocity. Using the high precision surface wave prospectingmethod, we can estimate underground S-wave velocity structures up to about 30 meters in depth. Themicrotremors survey method is a technique in which we observe microtremors with two-dimension arrayof seismometers and estimate underground S-wave velocity structures by means of inversion of the phasevelocity. Using the microtremors survey method, we can estimate underground S-wave velocity structuresfrom several meters to several thousand meters in depth.In this paper, the high precision surface wave prospecting method is used to estimate underground Swavevelocity structures shallower than 30 meters, and the microtremors survey method is used toestimate underground S-wave velocity structures about from 20 to 100 meters in depth. The S-wavevelocity structures obtained from these two methods are compared with those of well log. The resultsmake clear not only that these two survey methods can be performed with lower cost and but also that theyare effective to estimate underground S-wave velocity structures.