The Physical Basis of the Explosion Source and Generation of Regional Seismic Phases

Stevens, J. L.; Baker, G. Eli; Xu, Heming

doi:10.21236/ada475729

Cited by 9 publications

(8 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The complex excitation and energy-partitioning mechanisms yielding regional phases are difficult to empirically separate by data analysis. Thus, numerical modeling approaches are valuable for investigating excitation and propagation of regional seismic phases (e.g., McLaughlin and Jih, 1988;Xie and Lay, 1994;Jones, 1998, 1999;Wu et al, 2000a,b;Bonner, et al, 2003;Stevens et al, 2003;Myers et al, 2005;Stevens et al, 2005;Xie, Ge, and Lay, 2005;Xie, Lay, and Wu, 2005).…”

Section: Introductionmentioning

confidence: 99%

“…More recently, Bonner et al (2003) and Wu et al (2003) provided strong evidence in favor of the Rg-to-S scattering mechanism for the generation of the lowfrequency S and Lg for explosions. Stevens et al (2005) modeled the Rg-to-Lg scattering by assuming that Lg is generated by a distribution of surface scatters. Xie, Ge, and Lay (2005) and Xie, Lay, and Wu (2005) investigated the contribution of shallow volumetric scattering to explosion-source energy partitioning and calculated the frequency-dependent Lg excitation functions.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Explosion-Source Energy Partitioning and Lg-Wave Excitation: Contributions of Free-Surface Scattering

Xie

Lay

2008

Bulletin of the Seismological Society of America

View full text Add to dashboard Cite

A 2D boundary-element numerical simulation approach and a local slowness analysis method for an embedded array are used to quantify effects of topographic scattering on near-source energy partitioning for simple underground explosion sources. Various parameters, including free-surface models with different root mean square (rms) random topographic fluctuations and correlation lengths, source depths from 0.25 to 3 km, and Q values from 50 to infinity are included in the numerical simulations, with energy responses of different phases being determined as functions of frequency. The results reveal that for a crustal model with a relatively high surface velocity, near-source free-surface scattering provides an important coupling mechanism that can impart additional explosion energy to the Lg wave. At relatively low frequencies, and for a moderately rugged free-surface, the Rg-to-Lg transfer is quite efficient, while at higher frequencies or for a very rugged free surface, the body wave to Lg transfer may dominate the process. The Rg excitation functions, source depth, and topographic correlation length all contribute frequency dependence to the Lg excitation function. The presence of a low Q value within the uppermost crust severely attenuates the high-frequency energy transferred to the Lg wave.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Explosion-Source Energy Partitioning and Lg-Wave Excitation: Contributions of Free-Surface Scattering

Xie

Lay

2008

Bulletin of the Seismological Society of America

View full text Add to dashboard Cite

show abstract

“…Differing P and S corner frequencies would suggest that P-to-S conversion is not the dominant mechanism for S generation from underground explosions, as such a mechanism would be expected to produce S spectra with the same corner frequency as P (Fisk 2006). Further, recent observations and modeling suggest R g -to-S scattering may be less important than previously thought (Stevens et al 2006). Fisk (2006) conjectured that the S-wave spectrum from underground explosions in hard rock can be represented by the Mueller-Murphy explosion P wave source spectrum (Mueller & Murphy 1971), with S-wave corner frequency lower than P by the ratio of P to S wave speeds in the material around the source.…”

Section: Regional P/s Amplitude Ratiosmentioning

confidence: 95%

“…interaction of curved P wavefronts with the free-surface above the source (Lilwall 1988) and regional phase propagation in realistic 3D earth structure with topography (Myers et al 2003); 2. scattering from R g -to-S. This may be significant in the 1-5 Hz passband and depends on the explosion source depth (Myers et al 1999); 3. significant deviations from a point explosion source in an elastic medium with a free surface, such as the effect of spall (Blandford 1996, Stevens et al 2006; 4. cracking in some volume surrounding the detonation point (Blandford 1996).…”

Section: Regional P/s Amplitude Ratiosmentioning

confidence: 99%

Forensic Seismology and the Comprehensive Nuclear-Test-Ban Treaty

Bowers

Selby

2009

Annu. Rev. Earth Planet. Sci.

View full text Add to dashboard Cite

One application of forensic seismology is to help verify compliance with the Comprehensive Nuclear-Test-Ban Treaty. One of the challenges facing the forensic seismologist is to discriminate between the many thousands of earthquakes of potential interest each year and potential Treaty violations (underground explosions). There are four main methods: (a) ratio of bodyto surface-wave magnitudes, (b) ratio of high-frequency P to S energy, (c) model-based methods, and (d) source depth. Methods (a) and (b) have an empirical basis. The weakness of methods (a)-(c) is the lack of an equivalent elastic source for an underground explosion fired in the range of geological media found around the world. Reliable routine source-depth determination has proved difficult. However, experience gained in the past decade at identifying suspicious seismic sources suggests that although no single method works all of the time, intelligent and original application of complementary methods is usually sufficient to satisfactorily identify the source in question.

show abstract

“…Validation included estimating magnitudes for 8 Degelen, Kazakhstan, test site (DTS) and 10 Shagan, Kazakhstan, test site (STS) nuclear explosions and recorded at local distances by the Institute for Dynamics of the Geosphere (IDG). The datasets are described in Stevens et al (2007), which have excellent examples of Rg recorded at local distances. The test sites both have Rg velocity > 2 km=s resulting in a choice for the excitation correction, ET −1.…”

Section: Validation Of the Yield-m Rg Formulamentioning

confidence: 99%

MRg: A Magnitude Scale for 1 s Rayleigh Waves at Local Distances with Focus on Yield Estimation

Bonner

Russell

2013

Bulletin of the Seismological Society of America

View full text Add to dashboard Cite

Yield estimation of small explosions at local distances represents a challenge for the nuclear explosion monitoring community. We have examined the feasibility of using short-period surface-wave magnitudes, called M Rg , to estimate explosion yields at local distances (< 100 km). We have modified the Russell (2006) M s formula, which was derived for periods of 8-25 s for distances beyond 50 km, for application at local distances and 1 s period. We have studied short-period surface-wave attenuation in diverse lithologies in order to incorporate an attenuation term in the magnitude scale, which is suitable for Rg. We have also incorporated multiple excitation corrections for Rg based on the near-source seismic velocities, which greatly affect the source-region amplitudes for Rg. It is important to note that in the formula the excitation is estimated from the measured Rg group velocity. We have also derived a new Butterworth filter cutout definition for filtering Rg near 1 s period at distances between 2 and 100 km. We used the new formula to estimate M Rg for 39 small (37 ≤ Y ≤ 12;270 kg TNT equivalent) and shallow (< 120 m) explosions detonated in North America in lithologies ranging from alluvium to granite. Regressions of the magnitudes with yield result in the equation M Rg log 10 Y − 3:03 for chemical explosions with Y < 12;270 kg. An F factor with 95% confidence was determined to be 2.25, giving lower and upper bounds on the yield estimates of Y=2:25 and Y × 2:25, respectively. We applied the relationship M Rg log 10 Y − 3:33 (assuming factor of 2 equivalence between chemical and nuclear) to nuclear explosions detonated at the Degelen and Shagan, Kazakhstan, test sites. The estimated yields based on Rg magnitudes were often within 20% of the true yield and had smaller F factor than the estimated yields for United States chemical explosions.Online Material: Tables of event information and M Rg estimates.

show abstract

The Physical Basis of the Explosion Source and Generation of Regional Seismic Phases

Cited by 9 publications

References 50 publications

Explosion-Source Energy Partitioning and Lg-Wave Excitation: Contributions of Free-Surface Scattering

Explosion-Source Energy Partitioning and Lg-Wave Excitation: Contributions of Free-Surface Scattering

Forensic Seismology and the Comprehensive Nuclear-Test-Ban Treaty

MRg: A Magnitude Scale for 1 s Rayleigh Waves at Local Distances with Focus on Yield Estimation

Contact Info

Product

Resources

About