Table 4 - uploaded by Gene Ichinose
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An accident at the Sierra Chemical Company Kean Canyon plant, 16 krn east of Reno, Nevada, resulted in two explosions 3.52 sec apart that devastated the facility. An investigation into a possible cause for the accident required the de-termination of the chronological order of the explosions. We resolved the high-precision relative locations and chr...
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Context 1
... of our objectives was to see if it is feasible to mea- sure the separation between the explosions using the P or S waves. From Table 4, we see that the best estimate of the separation using the P waves is 80 m, which is consistent with the estimates using the N waves. However, the uncer- tainty in the time separation for the P-waves from WCN and PAH leads to a large uncertainty on the separation. ...
Citations
... Thus, a lot of the energy from surface explosions is lost to the atmosphere and therefore an increase in distance from the explosions results in smaller P and S waves than calculated by the predictor equations, such as at site 5 where the sensors were placed at greater distances than at the other sites. Ichinose, Smith, andAnderson (1998), Johnston (1987), and Evers et al. (2007) noted similar findings. In addition, site 4 is a good example of an area where the geology plays an important role, as noted by Johnston (1987) and Koper et al. (2002), who stated that even minimal changes in the anelastic structure can affect the predictor equations, and Redmayne and Turbitt (1991) who noted that different soils can magnify or diminish the values obtained from predictor equations by a factor of 4. The geological constants for regions 1, 2, 3, and 4 are similar for the USBM equation, indicating that the USBM is the more reliable PPV predictive equation for each of these sites, especially because geological constants of 1.2 are considered satisfactory (Atkinson, 2004;Atkinson and Mereu, 1992;Ford et al., 2014). ...
Most equations used to predict the ground motion produced by explosions were developed using confined blasts that were detonated for breaking rock in mining or tunnelling. Ground motion is usually recorded by geophones or seismometers. The air blast produced by open-pit blasts and explosions on the surface can pose a significant risk, thus microphones and pressure gauges are often also used to monitor the effects of the explosion. The aim of this study is to determine whether the predictive equations developed for confined explosions can be used to predict the effects from explosions on the surface, with appropriate adjustments to the various coefficients. Three predictive equations developed for buried explosions were tested. The study shows that the US Bureau of Mines peak particle velocity (PPV) predictive equation is the most reliable. In addition, a predictive equation that uses the secondary atmospheric shock wave phenomenon also produced good results, and uses the scaled delay time parameter, which is easier to measure. These equations may be utilized for demolition sites, where old and potentially unstable explosives and obsolete equipment are destroyed on the surface, and for assisting in forensic seismology to determine the details of an unexpected and unknown explosion.
... Seismic analyses enable me to refine the event origin time and location, and allow me to constrain the source properties such as source type and strength. These features allow me to use the seismic analyses for investigation of incidents (e.g., Ichinose et al., 1999;Kim et al., 2001;Koper et al., 2003;Evers et al., 2007). In particular, underwater explosions can be identified from wave-train composition and spectral features, and their source properties can be investigated using local and regional seismograms (Weinstein, 1968;Plutchok and Broome, 1969;Baumgardt and Der, 1998;Bowers and Selby, 2009). ...
... The energy peaks at frequencies of ∼32 Hz (Fig. 7). This energy corresponds to acoustic waves, which may develop from an explosive source or supersonic motion in the air or in a location close to the air (e.g., Kanamori et al., 1991;Ichinose et al., 1999;Koper et al., 1999;Stump et al., 2004;Gibbons et al., 2007). ...
A South Korean naval vessel sank on 26 March 2010. A seismic event with magnitude (M(L)) of 1.5 was observed at the time of vessel-sinking. Seismic waveforms were collected from three local stations. The event origin time is refined based on the P and S arrival times at the stations. The calculated event location and time are close to the reported vessel-sinking location and time, suggesting that the observed seismic event is associated with the vessel-sinking. The amplitudes of S waves are comparable to those of P waves. Seismic waves coupled from acoustic waves are observed, providing additional constraints of epicentral distance and source type. The coupled acoustic waves have a dominant frequency of similar to 32 Hz. The acoustic waves and high P/S amplitude ratios suggest an underwater explosion. The body-wave magnitude based on Pn is determined to be 1.46, which is consistent with the reported M(L). P energy is dominant at around 8.5 Hz, with multiple frequencies of 17.7 and 34.6 Hz. The primary frequency suggests the water-column thickness in the source region to be 44 m, which agrees with the reported value.
... The analysis of seismic records was important to the investigation because, as was clear from the reports, no more accurate estimates of the origin times of the explosions could be found. The importance of the seismic analysis in the investigation of industrial explosions has been well demonstrated, for example, by Ichinose et al. (1999) and Koper et al. (2003). ...
A sequence of explosions occurred in an ammunition factory in Novaky, Slovakia, on 2 March 2007 and caused a major industrial accident. The origin times and number of explosions were key aspects for the state investigation team to explain the primary cause and development of the accident. An analysis of seismic records was the only way to determine reliable origin times. We were able to identify the two strongest explosions directly from the seismic records. Detailed time-frequency analysis enabled us to identify acoustic waves caused by the explosions. This led to the subsequent identification of two weaker explosions in seismic records and an indication of two even weaker explosions that could not be identified in the records. The seismic analysis is supported by results of the onsite investigation by the state investigation team.
... The explosion of a gas pipeline in Ghislenghien, Belgium, was studied by combining seismic and infrasound data . Other examples of explosion sources studied using seismic data are the chemical plant explosion in Nevada (Ichinose et al. 1999) and the pipeline explosion in New Mexico (Koper et al. 2003). ...
A massive vapour cloud explosion occurred at the Buncefield fuel depot near Hemel Hempstead, UK, in the morning of 2005 December 11. The explosion was the result of an overflow from one of the storage tanks with the release of over 300 tons of petrol and generating a vapour cloud that spread over an area of 80000 m2, before being ignited. Considerable damage was caused in the vicinity of the explosion and a total of 43 people were injured. The explosion was detected by seismograph stations in the UK and the Netherlands and by infrasound arrays in the Netherlands. We analysed the seismic recordings to determine the origin time of 06:01:31.45 +/-0.5 s (UTC) from P-wave arrival times. Uncertainties in determination of origin time from acoustic arrival times alone were less than 10 s. Amplitudes of P-, Lg and primary acoustic waves were measured to derive decay relationships as function of distance. From the seismic amplitudes we estimated a yield of 2-10 tons equivalent to a buried explosion. Most seismic stations recorded primary and secondary acoustic waves. We used atmospheric ray tracing to identify the various travel paths, which depend on temperature and wind speed as function of altitude, leading to directional variation. Refracted waves were observed from the troposphere, stratosphere and thermosphere with a good match between observed and calculated traveltimes. The various wave types were also identified through array processing, which provides backazimuth and slowness, of recordings from an infrasound array in the Netherlands. The amplitude of stratospheric refracted acoustic waves recorded by the array microbarometers was used to estimate a yield of 21.6 (+/-5) tons TNT equivalent. We have demonstrated through joint seismo-acoustic analysis of the explosion that both the seismic velocity model and the atmospheric model are sufficient to explain the observed traveltimes.
... However, as the number of permanently installed instruments continues to grow, it is becoming common to record so-called exotic sources. Examples of exotic sources that have recently been studied seismically include supersonic aircraft (Kanamori et al., 1991), bolides (Chael and Spalding, 1996), rockfalls (Uhrhammer, 1996), geysers (Kedar et al., 1996), mine collapses (Pechmann et al., 1995;Yang et al., 1998), quarry blasts , industrial explosions (Ichinose et al., 1999), aircraft crashes (McCormack et al., 1999), and terrorist bombings (Holzer et al., 1996;Koper et al., 1999). ...
We analyze seismic and acoustic data from a series of controlled truck bomb explosions to develop scaling laws and functional relations between charge size and various waveform properties. The explosions had yields of 3-12 103 kg trinitrotoluene (TNT), and the receivers were placed at distances of 1-16 km, so the data mimic the data previously recorded from actual terrorist truck bombings. We examine four airblast properties (peak overpressure, impulse per unit area, pulse duration, and average shock velocity) and three seismic properties (peak displace- ment of P wave, low-frequency asymptote of displacement spectrum, and the corner frequency of displacement spectrum) as potential yield estimators. Impulse per unit area and pulse duration observations prove to be the most robust yield indicators; however, peak overpressure, peak displacement, and low-frequency spectral asymp- tote have significant utility as well. The acoustic scaling laws are more portable than the seismic scaling laws because regional differences in atmospheric structure can be well described by pressure and temperature observations, while regional differ- ences in geologic structure are dependent on a large number of less accessible pa- rameters. We apply the scaling laws developed here to seismic waveforms of the 1998 Nairobi bombing and find a yield of 2.0-6.0 103 kg TNT. This value is consistent with but more precise than a previous estimate made via a time domain waveform inversion. Additional testing indicates that our functional relations are likely applicable to surface chemical explosions in general and not limited solely to truck bombs.
On 19 August 2000 two seismometer networks in southeastern New Mexico recorded signals from a natural gas pipeline explosion. Analysis of the particle motion, arrival times, and durations of the seismic signals indicates that three impulsive events occurred with origin times of 11:26:18.8 ± 1.9, 11:26:43.6 ± 2.1, and 11:27:01.7 ± 2.0 (UCT). The first event was caused by the explosive blowout of the buried, high-pressure pipeline, and the second event was caused by the ignition of the vented natural gas. The nature of the third event is unclear; however, it was likely created by a secondary ignition. There were also two extended seismic events that originated at the same time as the first two impulsive events. The first resulted from the preignition venting of the gas and lasted for about 24 sec, while the second resulted from the postignition roaring of the flames and lasted for about 1 hr. Many of the source constraints provided by the seismic data were not available from any other investigative technique and thus were valuable to a diverse range of parties including the New Mexico state police, law firms involved in litigation related to the accident, the National Transportation and Safety Board, and the general public.
Earthquake sounds form an important part of the earthquake experience, and thus are a large part of artistic explorations of these events, but their study forms a small niche within seismology. The last few decades have produced the data necessary to finally understand this phenomenon along with its role in the study of earthquakes and explosions.
The moment tensors and centroid depths are estimated for eastern California and western Nevada earthquakes from regionally
recorded long-period seismograms using the moment-tensor inversion method. We compiled the moment tensor solutions into a
catalog complete for earthquakes with MW > 4 since 1990. The earthquakes in this study are mostly located within the aftershock zones of Eureka Valley, Double Spring
Flat, Coso, Ridgecrest, Fish Lake Valley, and Scotty's Junction, with the remaining earthquakes distributed across the region.
We validated the moment tensor solutions by a comparison with Harvard centroid moment tensor (CMT) and P-wave first-motion focal mechanism solutions. The mean difference in strike, dip, and rake between our moment tensors and
either Harvard CMT solutions or first-motion focal mechanisms were less than approximately 15° with a standard deviation less
than 10°. We also examine the solution mean and variance by inverting resampled datasets using the delete-j Jackknife resampling method. Based on two well-recorded sample events, with more than 11 and 14 associated recording stations,
the P- and T-axis trend and plunge can be determined to within ±10° when at least three or four well-distributed stations are used in
the inversion.
We separated the T-axis trends based on the approximate boundaries for three tectonic regions: Sierra Nevada, Walker Lane-eastern California
shear zone, and Basin and Range. Relative to the mean T-axis trend for the Sierra Nevada, the mean T-axis trend for the Walker Lane region is rotated clockwise by 25° and the mean T-axis trend for the Basin and Range is rotated clockwise by 40°. We separated the earthquakes into strike-slip and normal-slip
focal mechanisms based on a simple rake angle criterion. About 70% of modern earthquakes and 73% of the 11 large historical
earthquakes since 1860 are in the strike-slip category. The fraction of seismic moment released as strike-slip earthquakes
is approximately 50% for modern earthquakes and 75% for historical earthquakes. The difference is well within the variability
expected from short catalogs. These results emphasize the importance of the component of right-lateral shear within the region
and are qualitatively consistent with recent geodetic results.
On July 4th, 2006, a magnitude 5.1 earthquake occurred at Wen'an, ~100 km south of Beijing, which was felt at Beijing metropolitan area. To better understand the regional tectonics, we have inverted local and teleseismic broadband waveform data to determine the focal mechanism of this earthquake. We selected waveform data of 9 stations from the recently installed Beijing metropolitan digital Seismic Network (BSN). These stations are located within 600 km and cover a good azimuthal range to the earthquake. To better fit the lower amplitude P waveform, we employed two different weights for the P wave and surface wave arrivals, respectively. A grid search method was employed to find the strike, dip and slip of the earthquake that best fits the P and surface waveforms recorded at all the three components (the tangential component of the P-wave arrivals was not used). Synthetic waveforms were computed with an F-K method. Two crustal velocity models were used in the synthetic calculation to reflect a rapid east-west transition in crustal structure observed by seismic and geological studies in the study area. The 3-D grid search resulted in reasonable constraints on the fault geometry and the slip vector with a less well determined focal depth. As such we combined teleseismic waveform data from 8 stations of the Global Seismic Network in a joint inversion. Clearly identifiable depth phases (pP, sP) recorded by the teleseismic stations obviously provided a better constraint on the resulting source depth. Results from the joint inversion indicate that the Wen'an earthquake is mainly a right-lateral strike slip event (–150°) which occurred at a near vertical (dip, ~80°) NNE trending (210°) fault. The estimated focal depth is 14~15 km, and the moment magnitude is 5.1. The estimated fault geometry here agrees well with aftershock distribution and is consistent with the major fault systems in the area which were developed under a NNE-SSW oriented compressional stress field.
The moment tensors and centroid depths are estimated for eastern Cali-fornia and western Nevada earthquakes from regionally recorded long-period seis-mograms using the moment-tensor inversion method. We compiled the moment ten-sor solutions into a catalog complete for earthquakes with M W 4 since 1990. The earthquakes in this study are mostly located within the aftershock zones of Eureka Valley, Double Spring Flat, Coso, Ridgecrest, Fish Lake Valley, and Scotty's Junc-tion, with the remaining earthquakes distributed across the region. We validated the moment tensor solutions by a comparison with Harvard centroid moment tensor (CMT) and P-wave first-motion focal mechanism solutions. The mean difference in strike, dip, and rake between our moment tensors and either Harvard CMT solutions or first-motion focal mechanisms were less than approximately 15 with a standard deviation less than 10. We also examine the solution mean and variance by inverting resampled datasets using the delete-j Jackknife resampling method. Based on two well-recorded sample events, with more than 11 and 14 associated recording stations, the P-and T-axis trend and plunge can be determined to within 10 when at least three or four well-distributed stations are used in the inversion. We separated the T-axis trends based on the approximate boundaries for three tectonic regions: Sierra Nevada, Walker Lane–eastern California shear zone, and Basin and Range. Relative to the mean T-axis trend for the Sierra Nevada, the mean T-axis trend for the Walker Lane region is rotated clockwise by 25 and the mean T-axis trend for the Basin and Range is rotated clockwise by 40. We separated the earthquakes into strike-slip and normal-slip focal mechanisms based on a simple rake angle criterion. About 70% of modern earthquakes and 73% of the 11 large historical earthquakes since 1860 are in the strike-slip category. The fraction of seismic mo-ment released as strike-slip earthquakes is approximately 50% for modern earth-quakes and 75% for historical earthquakes. The difference is well within the vari-ability expected from short catalogs. These results emphasize the importance of the component of right-lateral shear within the region and are qualitatively consistent with recent geodetic results.
