Seismology in the United States—A retrospect

Abstract

Twenty years ago the total number of seismographic stations in the United States was only a fraction of those we have today. There was not a single first‐class station in continental United States. Even the number of second‐class stations was very small. Nearly all the stations were third‐class from every point of view‐equipment, time‐service, and personnel. Even among these many were comparatively inactive; some were not even operating.The Government stations in those days were divided into three groups. To the first group belonged those stations which were under the administration of the Weather Bureau. This was the Bureau officially responsible for seismology in the United States. It published station bulletins in the Monthly Weather Review. The principal stations in this group were Washington, D.C, Northfield, Vermont, and the cooperative station at the University of Chicago. Secondly, there was the station at Balboa Heights under the Canal Zone administration. The third group was maintained by the United States Coast and Geodetic Survey as an incidental activity and was particularly helpful in the interpretation of magnetograph‐records. The stations belonging to this group were located at Cheltenham, Tucson, Sitka, Honolulu, and Vieques (near Puerto Rico). Their equipment consisted for the most part of very low‐sensitivity horizontal pendulums of the Bosch type.