Discrimination Between Small Earthquakes and Quarry Blasts in Egypt Using Spectral Source Characteristics

Abstract

Source parameters calculated from displacement spectra of both P and S waves are used to discriminate between earthquakes and quarry blasts in three regions of Egypt during the 2009–2015 period. We use vertical component seismograms from 440 earthquakes and 450 quarry explosions with MD 1.5 to 3.3 to calculate source parameters, including scalar moments and corner frequencies. The Mo(P,S) vs. fc(P,S) and P- to S-wave corner frequency fc(P)/fc(S) ratios are used to distinguish quarry blasts from earthquakes. A comparison of Mo(P,S) vs. fc(P,S) for both earthquakes and explosions in Egypt demonstrates that explosions had significantly lower corner frequencies than earthquakes, particularly for S-wave displacement spectra. In contrast to the Northern and Central regions, the Southern Egyptian region provides a perfect separation of corner frequencies of earthquakes and explosions for both P- and S-waves. The empirically derived average ratio of fc(P)/fc(S) for earthquakes is 1.28, 1.26 and 1.26 in the Northern, Central and Southern Egyptian regions, respectively. For explosions, average fc(P)/fc(S) ratios are 1.89, 1.86 and 2.0 in the three Egyptian regions, respectively. According to these findings, the average ratio of fc(P) to fc(S) for explosions is higher than those for earthquakes, implying that the differences in ratios enhance the ability of the fc(P) vs. fc(S) approach to discriminate between earthquakes and explosions. Based on the average fc(P)/fc(S) ratios vs. Mw in the whole of Egypt, the observed fc(P)/fc(S) discrimination threshold value for separating quarry explosions from earthquakes is 1.51–1.52.

The micro‐seismicity of Co. Donegal (Ireland): Defining baseline seismicity in a region of slow lithospheric deformation

“…Two distinct low‐frequency arrivals can be found in the coda of such kind of events (Figure 3b). These patterns are widely recognized in anthropic seismicity (Korrat et al., 2022) (Saadalla et al., 2023) and can be used to classify the artificial events. We also performed a comparative spectral analysis between a natural earthquake and an artificial seismic signal.…”

Discrimination of quarry blasts from earthquakes in Northern and Central Egypt using linear and quadratic discriminant functions

“…The spectral ratio S r is a function of the frequency content of an event and is defined as the ratio of the integrated spectral amplitudes of the seismograms a(f) in each of the selected frequency bands (high-frequency band, h 1 -h 2 , and low-frequency band, l 1 -l 2 ). The frequency content of the events needed to determine S r was derived from the amplitude spectra computed using the Fast Fourier Transform in the previous work of Korrat et al (2022). C and S r can be written as follows in Eq.…”

“…To improve the credibility of the results, a combination and comparison of multiple methodologies were used. This work represents an extension of Korrat et al (2022) investigation of digital seismograms in Egypt for discriminating between earthquakes and quarry blasts.…”

Refining micro-seismic catalogs around Seydişehir, Turkey

“…One of the main separating features of artificial and natural quakes is the seismograms of vertical motion of seismic waves, especially the dominant P wave phase [Baumgard and Young, 1990;Gitterman et al, 1998;Horasan et al, 2009;Korrat et al, 2022]. Therefore, the vertical components of the station SEYD and SEDI, which are operated by KOERI-RETMC and AFAD, respectively were used for source type identification (Table 1).…”