A new technique utilizing theoretical wave forms has been developed to determine precise shear wave travel times. This technique was applied to long-period World-Wide Standard Seismograph Network and Canadian network seismograms of five large nuclear explosions to obtain a surface focus shear wave data set containing about 100 travel times for distances greater than 30 ø. Very little scatter is...

The elastic properties of the unconsolidated materials which cover most of the earth are, in general, unknown. In this paper, an attempt was made to measure, in the field, the shear and compressional wave velocities, with the emphasis on those for shear waves. For this purpose,'a simple source was devised which produced fairly pure shear waves. A portable refraction seismograph of standard desi...

Two recent developments in seismometry allow the study of seismic phenomena over a broad period range. Block and Moore [1970] developed a quartz accelerometer with the required stability and sensitivity to record seismic waves as well as earth tides. The instrument, especially useful at periods greater than 80 sec, recorded free oscillations of the earth associated with an earthquake of magnitu...