Seismic Characteristics of the Weight-Dropping Source

• Published in: Journal of Physics of the Earth Vol. 38; no. 3; pp. 189 - 212
• Main Authors: Ikawa, Takeshi, Abe, Susumu, Kobayashi, Yoshimasa
• Format: Journal Article
• Language: English
• Published: Tokyo The Seismological Society of Japan, The Volcanological Society of Japan, The Geodetic Society of Japan 1990; Japan Publications Trading
• Subjects: Applied geophysics; Earth sciences; Earth, ocean, space; Exact sciences and technology; Internal geophysics; Experience; Seismic methods; Synthetic seismogram; Seismic sources; Seismic source; Seismic signal; Synthetic seismograms; Experimental studies; Signals; Seismic method; Spectral analysis
• ISSN: 0022-3743; 1884-2305
• DOI: 10.4294/jpe1952.38.189

The mechanism of seismic wave generation by the weight-dropping method was investigated experimentally as well as theoretically with an object to improve the source apparatus used for high-resolution shallow surveys. Through a series of field experiments, we have studied factors which influence the characteristics of the generated seismic waves. We have drawn conclusions on the following subjects: (1) the dependence of the amplitude of seismic waves on the momentum of weight; (2) the dependence of the relative energy efficiency on the weight mass and the impact velocity; (3) the optimum selection of the mass of coupler (embedding body at the impact point) for a given weight mass in order to increase the amplitude of seismic waves. We propose simplified dynamic models for the weight-dropping source, and discuss their features briefly by comparing the observed waveforms with the synthesized ones.