Accession Number : AD0610944

Title :   COOPERATION IN SEISMIC MEASUREMENTS OF CRUSTAL STRUCTURE IN MINNESOTA.

Descriptive Note : Final progress rept. for 15 Apr 63-15 Oct 64,

Corporate Author : PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF GEOLOGY AND GEOPHYSICS

Personal Author(s) : Howell,B. F. ,Jr.

Report Date : 15 OCT 1964

Pagination or Media Count : 9

Abstract : Eighty-two one-ton charges of dynamite were detonated under controlled conditions at pre-selected points in Lake Superior. A network of seismic crews recorded the vibrations produced by these explosions. The frequency spectra are in many ways similar to those found for the Gulf of Maine by Nakamura and Howell (BULL. SEIS. SOC. AM. 54:9-18, 1964). There are frequent minima in the spectrum presumably due to interference (Nakamura, BULL. SEIS SOC. AM 54:1-8, 1964). These holes display no so-far-identified pattern. Unlike the Maine records, the Minnesota records do not show a strong difference in the spectrum between the direct and critically refracted pulse. This could mean that the Mohorovicic discontinuity in Minnesota is sharper than in Maine.

Descriptors :   (*SEISMOLOGY, MINNESOTA), (*MINNESOTA, SEISMOLOGY), UNDERWATER EXPLOSIONS, LAKES, SEISMIC WAVES, PROPAGATION, VELOCITY, MEASUREMENT, SEISMOGRAPHS, LITHOSPHERE, STRUCTURAL GEOLOGY

Distribution Statement : APPROVED FOR PUBLIC RELEASE