NEHRP Clearinghouse
- Title
- In situ Shear Wave Velocity Measurements on MIT Campus. Optimum Seismic Protection for New Building Construction in Eastern Metropolitan Areas.
- File
- PB293928.pdf
- Author(s)
- Murphy, V. J.
- Source
- National Science Foundation, Washington, DC. Applied Science and Research Applications., January 1973, 14 p.
- Identifying Number(s)
- INTERNAL STUDY-26
- Abstract
- Seismic field measurements were made to determine in-situ velocity values and elastic moduli of the overburden materials at the westerly end of the Massachusetts Institute of Technology campus. A seismic refraction line was also operated to measure the depths to bedrock and to provide velocity control for measurement intervals for the in-situ velocity studies. Field work was completed during the month of March, 1972. Three orthogonal geophones, two horizontal and one vertical, comprising a detector unit capable of measuring in three different directions, were used. One such unit was placed at each of three boreholes. The signals from these three-directional geophones, enhanced by amplification and filtering, were displayed on a photographic recording oscillograph employing 12 channels of a portable seismograph. Seismic energy was generated with small charges of explosives in a fourth hole. Timing lines were provided across the photographic records at two millisecond intervals. For the seismic refraction line, single geophones, vertical component only, were used at approximately 100-foot spacings along the line of investigation. These geophones were connected to a multi-conductor cable which in turn was connected to the recording instrumentation.
- Keywords
- Seismic velocity; Seismic design; Massachusetts Institute of Technology; Seismometers; Seismic waves; Massachusetts; Boreholes; Seismic arrays; Seismic refraction; Earthquake engineering; Cambridge (Massachusetts)