The Scientific Scrapbook


The first news of Rumania's earthquake, travelling nearly five miles a second, arrived at the Harvard Seismographic' station Sunday, thus beating out the UP and AP reports by one hour and seventeen minutes, it was learned last night.

Mr. L. Don Leet, assistant professor of Seismology, has measured velocities of 5.2 miles per second for "push" waves, a form imparting back and forward motion, which were travelling in the msterious upper mantle layer 21 miles below the surface of the earth. This is 1,440 miles per hour faster than any velocities yet recorded for this layer, and cannot be explained in terms of any familiar geological material or present theories about conditions of heat and pressure in the upper mantle layer.

The six Benioff Seismographs, most sensitive of any, at the station on Oak Ridge, Harvard, Mass., have been used by Dr. Lect to study the New England upper crust in collaberation with the Dominican Observatory, Ottawa, Williams College, Weston College, and Massachusetts Institute of Technology. By measurements of quake waves of both the "Push" and "Throb" variety, Dr. Lect has determined that the New England top layer consists of nine miles of hard granite.

The results obtained by Dr. Lect have enabled him to map, for the first time, the surface layers of the earth in the Newe England area down to the mysterious mantle, where the high velocity. of 5.2 miles per second was recorded. Dr. Lect said that the laws and conditions applying deep under ground are still imperfectly known.

The study involved determination of the location, and exact time of occurrence of the earthquakes, and also of the time of arrival of the various wave forms at the observing stations. The earthquake most important to the study occured in New Brunswick September 30, 1937, recorded on six stations. Other quakes observed took place in Canada, New Jersey, and various New England states; seven occured within fifteen miles of Times Square, New York City.