Interpretation of source functions of circum-Pacific earthquakes obtained from long-period Rayleigh waves

Abstract

The source functions of 53 shocks of the circum‐Pacific belt were obtained by a method of equalization applied to Rayleigh waves in the period range of 35 sec to 150 sec recorded at the Seismological Laboratory, Pasadena. The source function was interpreted in terms of the direction of forces at the source. The interpretation was checked by additional information concerning the earthquake as well as by an error analysis. The horizontal forces deduced from the source function showed a systematic geographic distribution, which favors Benioff's hypothesis on the circum‐Pacific tectonics. The vertical forces are found to be mostly directed upward on the oceanic side.

Movements on Major Transcurrent Faults

“…2. Slip Polarities For the remaining portion of the arc from Japan to the Kermadec Islands, the only significant faulting information is given by Ald's studies of the source functions derived from phase equalization of Rayleigh waves from a large number of small circum-Pacific earthquakes, magnitudes 5¾ to 6¾, located in this region [31,32]. Since this method depends upon the whole movement of the source, it should be more reliable than the first-motion methods which operate on the beginning transients only.…”

Long Period Seismic Methods for Identifying Small, Underground Nuclear Explosions

“…For the purposes required here it is sufficient to note that N(u),h) is dependent on frequency, layer thicknesses, elastic parameters of the layers and source depth but is independent of source type and geometry. |L(a))|e is the source temporal factor or Fourier transform of the source time function and has been investigated by Haskell (1964bHaskell ( , 1966, Aki (1960a), Ben-Menahem and Toksoz (1962Toksoz ( , 1963 and Tsai (1969).…”