Identification of earthquakes and explosions by use of teleseismic data

Evernden, Jack F.

doi:10.1029/jb074i015p03828

Cited by 86 publications

(42 citation statements)

References 7 publications

(4 reference statements)

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“…In order to analyze the characteristics of the site response of the stations used, we calculated horizontal to vertical spectral In section 1 we discussed that the estimates of K, made using equation ( To test if the variability of • was due to hypocentral mislocations, we relocated all the events using the master event technique [e.g., Evernden, 1969;Bott and Wong, 1995]. Table 4 indicate that in the direction perpendicular to the orientation of the faults the attenuation is high at short epicentral distances and shallow depths (above 10 km, based on focal depths).…”

Section: Introductionmentioning

confidence: 99%

The spectral decay parameter κ in the region of Umbria‐Marche, Italy

Castro¹,

Trojani²,

Monachesi³

et al. 2000

J. Geophys. Res.

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Abstract. We analyze 44 earthquakes (M2.1-4.1) recorded by the Marchesan Seismograph Network during the 1997 Umbria-Marche sequence. We calculated the spectral decay parameter g [Anderson and Hough, 1984] using 33 events (M2.2-4.1) and fc < 10 Hz located in the middle of the rupture area. Although the source-station paths have approximately the same distance (+_2.5 km) and azimuth for a given site, the estimates of g show great variability at all the stations. Even events with small standard deviation on the estimate of g can have a value 2-3 times different from that estimated for other events located within the 2.5 km. This observation suggests that the attenuation near the source can change significantly in a small distance range. We separated source and path effects by performing a generalized spectral inversion. We dismissed events with source functions having corner frequencies between 10 and 20 Hz, the frequency band where g was estimated. With the best estimates of g we calculated the mean for each site, and we observed an apparent azimuthal variation of the attenuation. We used the observed changes of g to estimate the near-source attenuation, finding that in a distance of 2 km, Q may vary between 16 and 52, depending on the source-station direction. The results of the analysis suggest that the most likely cause of the observed variability of g is the spatial variation of Q near the seismogenic zone. IntroductionThere are different propagation factors that control the spectral characteristics of strong ground motion, such as the velocity structure of the medium and the site conditions near the surface. However, at high frequencies, attenuation is one of the most important factors controlling the decay of the amplitudes and the shape of the spectrum.On the basis of the idea that at high frequencies (f greater than the corner frequency) the displacement spectral amplitudes predicted by standard source models [e.g., Brune, 1970] fall off proportionally to 0.} -2 , Anderson and Hough [1984] proposed that the shape of the acceleration spectrum can be described by a(f) = Aoe -•, f > fE,where K is the spectral decay parameter, which is controlled by the attenuation along the path and at the site; A0 depends on source, epicentral distance, and other factors; and f•r is the frequency above which the spectral amplitude follows an exponential decay. In this approach, the path effect is obtained from the observed spectrum by using a source reference model (the 0.} 2 model) and assuming that any additional falloff is due to attenuation. In addition, when the observed acceleration spectra can be characterized by the exponential decay, the spectral shape becomes insensitive to the frequency dependence of Q

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Section: Introductionmentioning

confidence: 99%

The spectral decay parameter κ in the region of Umbria‐Marche, Italy

Castro¹,

Trojani²,

Monachesi³

et al. 2000

J. Geophys. Res.

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“…Many of the other MS20-mb studies (Capon et al, 1967;Lieberman and Pomeroy, 1969;Basham, 1969;Basham et al,1970;Evernden, 1969Evernden, , 1971and others) have been made largely from data recorded at the Large Aperture Seismic Array (LASA), at stations in the EUS, or at Canadian stations predominantly on the -338-TR 72-3 Shield. Also, EUS stations have been used to obtain teleseismic data from NTS explosions.…”

Section: The Ms/mb Discriminantmentioning

confidence: 99%

“…The difference between the energy content of explosions and earthquakes in the long-period and short-period passbands is the basis for the more effective discrimination criteria (Evernden, 1969).…”

Section: The Ms/mb Discriminantmentioning

confidence: 99%

Development of LP Wave Discrimination Capability Using LP Strain Instruments

Fix¹,

Sherwin²

1970

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“…In an effort to reduce the error of relative location, with the hope that we might be able to detect a spatial structure which was less likely to be a product of location error, we relocated the earthquakes using the master event technique (Evernden, 1969), as applied to tightly grouped local earthquake sequences. Residuals from a single well-located earthquake were used in the location procedure as station corrections.…”

Section: Acknowledgmentsmentioning

confidence: 99%

Earthquake hazard evaluation in the Pacific Northwest

Crosson¹

1981

Open-File Report

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Identification of earthquakes and explosions by use of teleseismic data

Cited by 86 publications

References 7 publications

The spectral decay parameter κ in the region of Umbria‐Marche, Italy

The spectral decay parameter κ in the region of Umbria‐Marche, Italy

Development of LP Wave Discrimination Capability Using LP Strain Instruments

Earthquake hazard evaluation in the Pacific Northwest

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