OCR Text |
Show Speaker Explains Seismology Science v Seismologists, using earthquake waves as their "feelers," are able to take up where geologists are compelled to leave off and they obtain information about the deeper structures of the earth that never will be visible any other way, Dr. James B. Macel-wayne, Macel-wayne, S. J., director of the Institute of Applied Geophysical Technology, St. Louis, Mo., declared de-clared in a lecture at Utah State Agricultural college Thursday night. Speaking before members of the USAC chapter of Sigma Xi and a large number of ,guests, Dr. Macelwayne pointed out the use of practical or applied earth-physics earth-physics to determine oil pools, ore deposits, solid sites for bridges, dams and other massive works of man. In this work, slight local dlf-, ferences in the earth's gravitational, gravita-tional, magnetic, and electric , fields, measurable with sensitive ' instruments, yield important and useful data, he pointed out. "Pure seismology" delves even deeper, obtaining a sweeping pic- j I - the ' relatively thin crust of the earth there is a 600-mile deep ' layer of denser material, in which the velocity of earthquake waves increase rapidly with depth. Then comes a layer about 1100 miles deep, in which speed does not increase so rapidly with depth.: ; After a thin transitional zone, comes the dense inner core of the "earth, comprising slightly more than half its diameter, which focuses earthquake waves like a great spherical lens, he declared. "In spite of limitations, the geologist has given us a fairly accurate. . picture of the first few hundred feet of the crust of the earth over a surprisingly large part of the globe, Dr. Macelwayne continued. "But for the less accessible., ac-cessible., parts of the subsurface and for greater depths, the new science of geophysics has come to our rescue with its diverse methods meth-ods and apparatus." ' Comparing geophysics to a department de-partment store, he asserted that it gathers together under the same roof many different dis ciplines that have one important characteristic in common they ' all apply physical principles, methods, and apparatus to the study of the earth and its envelopes. en-velopes. It is especially the science of seismology that has thrown the greatest light on the buried depths of our planet, Dr. Macelwayne Macel-wayne told the group. Exploration seismology or seismic prospecting, with its inflection and refraction j methods, is capable under favorable favor-able circumstances of outlining buried surfaces to a surprisingly ! high degree of precision down ' to depths of several miles. 1 Earthquake seismology carries the investigation through the I deeper crust into the outer and inner mantle and eventually into the central core of the earth. He illustrated the procedures followed with photographs, curves and drawings. "As a result, modern geophysical geophys-ical research has given us an outline out-line picture of the interior of our globe that is fascinating and ex-j ex-j tremely valuable," he declared. ture of the earths general structure struc-ture from the surface to center by mathematical studies of earthquake earth-quake waves," he said. Beneath ' |