The ratio between corner frequencies of source spectra of P- and S-waves—a new discriminant between earthquakes and quarry blasts

G. Ataeva, Y. Gitterman, A. Shapira

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

This study analyzes and compares the P- and S-wave displacement spectra from local earthquakes and explosions of similar magnitudes. We propose a new approach to discrimination between low-magnitude shallow earthquakes and explosions by using ratios of P- to S-wave corner frequencies as a criterion. We have explored 2430 digital records of the Israeli Seismic Network (ISN) from 456 local events (226 earthquakes, 230 quarry blasts, and a few underwater explosions) of magnitudes Md = 1.4–3.4, which occurred at distances up to 250 km during 2001–2013 years. P-wave and S-wave displacement spectra were computed for all events following Brune’s source model of earthquakes (1970, 1971) and applying the distance correction coefficients (Shapira and Hofstetter, Teconophysics 217:217–226, 1993; Ataeva G, Shapira A, Hofstetter A, J Seismol 19:389-401, 2015), The corner frequencies and moment magnitudes were determined using multiple stations for each event, and then the comparative analysis was performed. The analysis showed that both P-wave and especially S-wave displacement spectra of quarry blasts demonstrate the corner frequencies lower than those obtained from earthquakes of similar magnitudes. A clear separation between earthquake and explosion populations was obtained for ratios of P- to S-wave corner frequency f0(P)/f0(S). The ratios were computed for each event with corner frequencies f0 of P- and S-wave, which were obtained from the measured f0 I at individual stations, then corrected for distance and finally averaged. We obtained empirically the average estimation of f0(P)/f0(S) = 1.23 for all used earthquakes, and 1.86 for all explosions. We found that the difference in the ratios can be an effective discrimination parameter which does not depend on estimated moment magnitude Mw. The new multi-station Corner Frequency Discriminant (CFD) for earthquakes and explosions in Israel was developed based on ratios P- to S-wave corner frequencies f0(P)/f0(S), with the empirical threshold value of the ratio for Israel as 1.48.

Original languageEnglish
Pages (from-to)209-220
Number of pages12
JournalJournal of Seismology
Volume21
Issue number1
DOIs
StatePublished - 1 Jan 2017
Externally publishedYes

Keywords

  • Event discrimination
  • P- and S-wave corner frequency
  • Seismic source parameters
  • Spectral displacement

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

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