BERMUDA T PHASES WITH LARGE CONTINENTAL PATHS
Abstract
Results are presented from an investigation of earthquakes of magnitude greater than 6 1.2 occurring in southern Mexico, Central America, and South America since the installation of Benioff short-period seismographs on Bermuda in 1951. Selected Benioff short-period vertical records from the San Juan station were also used in the investigation. A short-period arrival on records of the Bermuda-Columbia Seismograph Station is identified as the T phase. The following conclusions were reached i the study of T phases generated by inland earthquakes; (1) the energy travels as P before entering the water, and the S phase is not an effective generator of T at the Puerto Rico Scorp; (2) a deep-focus earthquake is a better generator of this T phase; (3) both magnitude and frequency of the P phase are critical in determining whether it will generate a T phase a T phase upon its arrival at a steep submarine slope; (4) a T phase will be generated by the arrival of a P phase at a steep submarine slope if the P phase contains energy within the characteristic frequency range of the T phase, and this T phase can be detected at distant stations if there are no obstacles in the path between the submarine slope and the station; (5) the P-T transmission could have been predicted by considerations of reciprocity from earlier observation at inland stations; and (6) background noises in the Sofar channel arise in some cases from earthquakes as much as several thousand miles inland.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1953
- Accession Number
- AD0020539
Entities
People
- D. H. Shurbet