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1.
Heming Xu Arthur J. Rodgers Ilya N. Lomov Oleg Y. Vorobiev 《Pure and Applied Geophysics》2014,171(3-5):507-521
Seismic source characteristics of low-yield (0.5–5 kt) underground explosions are inferred from hydrodynamic simulations using a granite material model on high-performance (parallel) computers. We use a non-linear rheological model for granite calibrated to historical near-field nuclear test data. Equivalent elastic P-wave source spectra are derived from the simulated hydrodynamic response using reduced velocity potentials. Source spectra and parameters are compared with the models of Mueller and Murphy (Bull Seism Soc Am 61:1675–1692, 1971, hereafter MM71) and Denny and Johnson (Explosion source phenomenology, pp 1–24, 1991, hereafter DJ91). The source spectra inferred from the simulations of different yields at normal scaled depth-of-burial (SDOB) match the MM71 spectra reasonably well. For normally buried nuclear explosions, seismic moments are larger for the hydrodynamic simulations than MM71 (by 25 %) and for DJ91 (by over a factor of 2), however, the scaling of moment with yield across this low-yield range is consistent for our calculations and the two models. Spectra from our simulations show higher corner frequencies at the lower end of the 0.5–5.0 kt yield range and stronger variation with yield than the MM71 and DJ91 models predict. The spectra from our simulations have additional energy above the corner frequency, probably related to non-linear near-source effects, but at high frequencies the spectral slopes agree with the f ?2 predictions of MM71. Simulations of nuclear explosions for a range of SDOB from 0.5 to 3.9 show stronger variations in the seismic moment than predicted by the MM71 and DJ91 models. Chemical explosions are found to generate higher moments by a factor of about two compared to nuclear explosions of the same yield in granite and at normal depth-of-burial, broadly consistent with comparisons of nuclear and chemical shots at the US Nevada Test Site (Denny, Proceeding of symposium on the non-proliferation experiment, Rockville, Maryland, 1994). For all buried explosions, the region of permanent deformation and material damage is not spherical but extends along the free surface above and away from the source. The effect of damage induced by a normally buried nuclear explosion on seismic radiation is explored by comparing the motions from hydrodynamic simulations with those for point-source elastic Green’s functions. Results show that radiation emerging at downward takeoff angles appears to be dominated by the expected isotropic source contribution, while at shallower angles the motions are complicated by near-surface damage and cannot be represented with the addition of a simple secondary compensated linear vector dipole point source above the shot point. The agreement and differences of simulated source spectra with the MM71 and DJ91 models motivates the use of numerical simulations to understand observed motions and investigate seismic source features for underground explosions in various emplacement media and conditions, including non-linear rheological effects such as material strength and porosity. 相似文献
2.
—?Improving the performance of short-period regional seismic discriminants by applying propagation corrections is explored using observations from two seismic monitoring stations in Asia. Frequency-dependent regional phase amplitude ratio measurements at stations NIL and ZAL for earthquakes and underground nuclear explosions were obtained from the prototype-International Data Center (pIDC) that has been established for developing monitoring capabilities of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The pIDC discriminant measurements have large scatter, much of which is attributed to wave propagation effects in the heterogeneous crustal waveguide. Linear regressions indicate that the phase ratios are correlated with topographic characteristics along the individual paths, providing an empirical means for correcting for path effects beyond conventional distance corrections. Kriging, a spatial multiple regression algorithm, also reveals coherent spatial patterns in the data indicative of regional path effects. Using available high-resolution topography data, correction of regional P/S ratios for the best models obtained from multivariate regressions systematically reduces the data variance relative to distance corrections alone, as has been observed for other data sets. The reduced scatter in the measurements increases the separation between earthquake and explosion populations in most cases, enhancing the regional discriminant performance. The path-corrected discriminants isolate explosions better for NIL than for ZAL, even though some of the explosion sources are located in a common source area. Kriging achieves comparable or superior variance reduction for the discriminant measures, without requiring knowledge of the path structure, although this may not result in improved discriminant performance. While always desirable, corrections for heterogeneous path effects may prove inadequate in some cases, notably when phase blockage occurs or when strong attenuation eliminates the diagnostic high-frequency energy. 相似文献
3.
D. N. Anderson H. J. Patton S. R. Taylor J. L. Bonner N. D. Selby 《Pure and Applied Geophysics》2014,171(3-5):537-547
The Comprehensive Nuclear-Test-Ban Treaty (CTBT), a global ban on nuclear explosions, is currently in a ratification phase. Under the CTBT, an International Monitoring System (IMS) of seismic, hydroacoustic, infrasonic and radionuclide sensors is operational, and the data from the IMS is analysed by the International Data Centre (IDC). The IDC provides CTBT signatories basic seismic event parameters and a screening analysis indicating whether an event exhibits explosion characteristics (for example, shallow depth). An important component of the screening analysis is a statistical test of the null hypothesis H 0: explosion characteristics using empirical measurements of seismic energy (magnitudes). The established magnitude used for event size is the body-wave magnitude (denoted m b) computed from the initial segment of a seismic waveform. IDC screening analysis is applied to events with m b greater than 3.5. The Rayleigh wave magnitude (denoted M S) is a measure of later arriving surface wave energy. Magnitudes are measurements of seismic energy that include adjustments (physical correction model) for path and distance effects between event and station. Relative to m b, earthquakes generally have a larger M S magnitude than explosions. This article proposes a hypothesis test (screening analysis) using M S and m b that expressly accounts for physical correction model inadequacy in the standard error of the test statistic. With this hypothesis test formulation, the 2009 Democratic Peoples Republic of Korea announced nuclear weapon test fails to reject the null hypothesis H 0: explosion characteristics. 相似文献
4.
5.
J. R. Murphy D. D. Sultanov N. Rimer B. W. Barker 《Pure and Applied Geophysics》2001,158(11):2105-2121
—?During the period from 1975 to 1979, the former Soviet Union conducted a series a six nuclear explosions in a water-filled cavity in salt which was created in 1968 by a tamped 27?kt explosion at a depth of 597?m at the Azgir test site at the north end of the Caspian Sea. Broadband, near-regional seismic data recorded from these tests have been processed and analyzed in an attempt to characterize the seismic source characteristics of these explosions and assess their relevance to the cavity decoupling evasion scenario. The results of these analyses indicate that the explosions in the water-filled cavity were not decoupled, but rather show evidence of enhanced seismic coupling with respect to that which would be expected from tamped explosions of the same yields in salt. Theoretical finite difference simulations of these tests have been conducted in which the complex, nonlinear interactions between the shock effects in both the water and surrounding salt medium have been explicitly modeled. The results of these simulations indicate that the most prominent yield dependent features of the observed seismic source functions can be largely explained by the dynamic interactions between the expanding and contracting steam bubbles generated by the explosions in water and the shock-wave reflections from the cavity wall. More specifically, it has been found that the shock-wave reflection from the cavity wall retards the expansion of the steam bubble in a yield dependent fashion relative to that expected in the open ocean, resulting in a smaller maximum bubble radius and a shorter bubble oscillation period. 相似文献
6.
选取首都圈地区2008年8月——2009年9月ML在2.0——2.2范围内的爆破、矿塌和天然地震数据资料,从时间域和频率域进行分析对比,总结出识别爆破、矿塌和天然地震的依据．在时域方面,爆破的初动方向向上,矿塌向下,天然地震的初动方向依赖于台站的分布情况;爆破和矿塌的面波比较发育;天然地震的S波与P波最大振幅比(AS/AP)大于爆破和矿塌,同时,爆破和矿塌的能量衰减比天然地震快．在频域方面,高频成分的能量衰减快于低频;天然地震的拐角频率较高,爆破次之,矿塌的最小;在震中距200 km范围内,爆破的顶峰频率主要分布在5——7 Hz,矿塌分布在2——4 Hz,天然地震的顶峰频率较大,在10——18 Hz范围内.另外,天然地震的频率域较宽,其次为爆破、矿塌． 相似文献
7.
Yu. F. Kopnichev I. N. Sokolova K. N. Sokolov 《Izvestiya Physics of the Solid Earth》2013,49(6):786-795
The characteristics of the attenuation field of short-period shear waves in the region of Nevada nuclear test site (NNTS) are studied. The seismograms of underground nuclear explosions (UNEs) and earthquakes recorded by three seismic stations in 1975–2012 at the epicentral distances of up to 1000 km are processed by the methods based on the analysis of the amplitude ratios of Sn to Pn and Lg to Pg waves, as well as the S-coda envelopes for close events. It is shown that the structure of the attenuation field in the Earth’s crust and upper mantle in the NNTS region experienced significant temporal variations during the interval of nuclear operations. The strongest variations were associated with UNEs conducted in the Pahute Mesa area, which held about two-thirds of the most intense explosions. Our data indicate that temporal variations in the structure of the attenuation field are related to the migration of deep fluids. A comparison of the general characteristics of the attenuation field in the regions of the three large nuclear test sites is presented. 相似文献
8.
The results of numerical simulation of the nonlinear evolution of an acoustic pulse propagating above an earthquake epicenter with preset energy parameters are presented. The interaction with charged plasma particles in the lower ionosphere is taken into account. The interaction between neutral and charged components is described by the diffusion mechanism of the disturbance of the density of charged ionospheric plasma components. The simulation was carried out for three values of earthquake magnitude M = 5; 6; and 7. It is ascertained that the numerical simulation results agree with analytical estimates made during the study of main regularities of seismic events that induce weak nonlinear effects in the atmosphere. 相似文献
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T waves (seismic water waves), which were generated by deep-focused earthquakes, have been found by an array of sensitive ocean-bottom seismographic observations depolyed on the western Pacific basin. The points of generation of T waves have been exactly located by use of the accurate velocity of water waves which were known from explosions. The positions obtained are at the bottom of deep-sea trenches; however, the positions are slightly (10–35 km) ocean-side of the trench. T waves have been known to be generated by seismic waves which were transmitted from the focus to the trench bottom along the descending lithosphere. The intensity of the observed T waves implies that the Q value along the descending lithosphere is more than 4000. The positions of T-wave generation are consistent with the 8.2- to 8.6-km/s stratified structure of the oceanic lithosphere. T waves from shallow earthquakes beneath the lower continental slope are also clearly observed by bottom seismography. 相似文献
10.
Seismic records produced by different seismic sources vary. In this study, we compared the waveform records and time-frequency characteristics of tectonic earthquakes, artificial explosions, and mine collapses in China’s Capital Region. The results show that tectonic earthquakes are characterized by stronger S-wave energy than P-wave energy, obvious high-frequency components, and wide frequency bands of P and S waves. Artificial explosions are characterized by greater P-wave amplitude than S-wave amplitude and near-station surface wave development. Mine collapses are characterized by lower overall frequency, more obvious surface waves, and longer duration. We extracted quantitative discriminants based on the analysis of different event records, with 31 feature values in 7 categories (P/S maximum amplitude ratio, high/low frequency energy ratio, P/S spectral ratio, corner frequency, duration, the second-order moment of spectrum, and energy strongest point). A comparison of the ability of these feature values to recognize distinct events showed that the 6–17 Hz P/S spectral ratio was able to completely distinguish artificial explosions from the other two types of events. The S-wave corner frequency performed relatively well in identifying all three types of events, with an accuracy of over 90%. Additionally, a support vector machine was used to comprehensively distinguish multiple features, with an accuracy for all three types of events reaching up to 100%. 相似文献
11.
2015年8月12日发生在天津滨海新区的化学品爆炸事故造成了严重的人员伤亡和财产损失。 基于区域地震台网记录的数字化连续地震波形资料, 对爆炸发生过程的精细分析是深入调查爆炸事故发生原因、 快速估计事故所造成灾害与损失的重要手段之一。 本文首先利用震相到时和质点运动轨迹信息对记录波形中能量较强的震相性质进行分析, 再通过模板匹配算法检测爆炸过程中是否存在两次大爆炸以外的小爆炸事件, 并对检测方法的效能进行检验, 最后依据波形互相关得到的震相到时差估计两次较大爆炸的相对位置。 计算结果显示区域台网记录波形中能量最大的体波震相可能为沿沉积层顶部传播的Pg震相, 垂直向能量最强的面波震相为Rg震相, 而能量较弱的初至震相可能为结晶基底首波; 爆炸过程中除了两次能量较大的爆炸以外还能检测到两次较小的爆炸事件, 其当量相当于约ML0.5的地震; 基于两次大爆炸Pg震相相对到时信息得到第二次大爆炸发生在第一次大爆炸的北西侧, 两次爆炸位置距离约50~55 m。 本文研究结果为爆炸事故的调查分析提供了地震学依据。 相似文献
12.
J. R. Murphy I. O. Kitov B. W. Barker D. D. Sultanov 《Pure and Applied Geophysics》2001,158(11):2077-2101
—?During the period 1965 to 1988, the former Soviet Union (FSU) conducted over 120 peaceful nuclear explosions (PNE) at locations widely dispersed throughout the territories of the FSU. These explosions sample a much wider range of source conditions than do the historical explosions at the known nuclear test sites and, therefore, seismic data recorded from these PNE tests provide a unique resource for use in deriving improved quantitative bounds on the ranges of seismic signal characteristics which may require consideration in global monitoring of the Comprehensive Test-Ban Treaty (CTBT). In this paper we summarize the results of a detailed statistical analysis of broadband seismic data recorded at the Borovoye Geophysical Observatory from 21 of these PNE tests at regional distances extending from about 7 to 19 degrees, as well as the results of theoretical waveform simulation analyses of near-regional (Δ?相似文献
13.
本文通过地震正演模型和面波振幅数据对比分析了天然地震、爆炸,与核试验数据,以探索改进辨别天然地震与爆炸的方法。所提方法是基于波数域和频率域的双积分变换解。用于研究的地震事件都发生在北朝鲜,其中包括2001年6月26日（39.212°N,125.383°E）和2001年10月30日（38.748°N,125.267°E）所记录的爆炸数据,2006年10月9日（41.275°N,129.095°E）所记录的一次核试验数据、以及2002年4月14日（39.207°N,125.686°E）和2002年6月7日（38.703°N,125.638°E）所记录的两次天然地震。基于这些数据通过地震波分析与理论模拟表明爆炸引起的地震与天然地震有着不同的波型特征。爆炸引起的信号特征是P波的能量较S波强,在爆炸记录上0.05-0.5Hz频率之间Rg波清晰呈现,而在然地震记录上没有。这是由于爆炸地震记录上P波是优势波,与SH成分发生了耦合。 相似文献
14.
The sequence of large Vulcanian explosions occurring at the andesitic Popocatépetl volcano, Mexico during November 1998 to April 1999 was studied. The size of 26 largest explosions was estimated from broadband seismic records at the distance of 4 km from the crater. The sequence began with the largest explosion (E = 2.6 × 1012 J) occurring on 25 November at 08:05, and following largest daily explosions were characterized by gradual decrease in the energy. The energy of 20 large (E ≥ 1011 J) explosions was distributed as Student's t-distribution with a geometrical mean Log E = 11.81 (J). 相似文献
15.
—?Official Russian sources in 1996 and 1997 have stated that 340 underground nuclear tests (UNTs) were conducted during 1961–1989 at the Semipalatinsk Test Site (STS) in Eastern Kazakhstan. Only 271 of these nuclear tests appear to have been described with well-determined origin time, coordinates and magnitudes in the openly available technical literature. Thus, good open documentation has been lacking for 69 UNTs at STS.¶The main goal of our study was to provide detections, estimates of origin time and location, and magnitudes, for as many of these previously undocumented events as possible. We used data from temporary and permanent seismographic stations in the former USSR at distances from 500?km to about 1500?km from STS. As a result, we have been able to assign magnitude for eight previously located UNTs whose magnitude was not previously known. For 31 UNTs, we have estimated origin time an d assigned magnitude — and for 19 of these 31 we have obtained locations based on seismic signals. Of the remaining 30 poorly documented UNTs, 15 had announced yields that were less than one ton, and 13 occurred simultaneously with another test which was detected. There are only two UNTs, for which the announced yield exceeds one ton and we have been unable to find seismic signals.¶Most of the newly detected and located events were sub-kiloton. Their magnitudes range from 2.7 up to 5.1 (a multi-kiloton event on 1965 Feb. 4 that was often obscured at teleseismic stations by signals from an earthquake swarm in the Aleutians).¶For 17 small UNTs at STS, we compare the locations (with their uncertainties) that we had earlier determined in 1994 from analysis of regional seismic waves, with ground-truth information obtained in 1998. The average error of the seismically-determined locations is only about 5?km. The ground-truth location is almost alw ays within the predicted small uncertainty of the seismically-determined location.¶Seismically-determined yield estimates are in good agreement with the announced total annual yield of nuclear tests, for each year from 1964 to 1989 at Semipalatinsk.¶We also report the origin time, location, and seismic magnitude of 29 chemical explosions and a few earthquakes on or near STS during the years 1961–1989.¶Our new documentation of STS explosions is important for evaluating the detection, location, and identification capabilities of teleseismic and regional arrays and stations; and how these capabilities have changed with time. 相似文献
16.
本文分析了河北怀来多次爆炸、河北三河采石场多次爆炸和低震级天然地震事件的记录特征和时频差异。结果显示:河北怀来爆炸的P波能量强、衰减快、S波发育弱;河北三河采石场爆炸的P波、S波主频均低于怀来爆炸,S波与面波混淆,不同震中距的台站记录低频发育明显;而天然地震的有效频带更宽,频率成分更为复杂。将Pg/Sg谱比判据应用于小震级地震与爆炸的识别中,探索交叉频带谱比对不同地区爆炸的识别。结果表明:高频（＞5 Hz）Pg/Sg谱比判据可将研究数据中的爆炸与小震级地震完全区分;与Sg低频（0—2 Hz）有关的交叉频带谱比可对两个不同地区的爆炸进行识别,交叉频带的谱比判据较传统的单一频带谱比判据能够更好地反映出不同类型事件的特征差异。 相似文献
17.
Three large-scale on-surface explosions were conducted by the Geophysical Institute of Israel (GII) at the Sayarim Military Range, Negev desert, Israel: about 82 tons of strong high explosives in August 2009, and two explosions of about 10 and 100 tons of ANFO explosives in January 2011. It was a collaborative effort between Israel, CTBTO, USA and several European countries, with the main goal to provide fully controlled ground truth (GT0) infrasound sources, monitored by extensive observations, for calibration of International Monitoring System (IMS) infrasound stations in Europe, Middle East and Asia. In all shots, the explosives were assembled like a pyramid/hemisphere on dry desert alluvium, with a complicated explosion design, different from the ideal homogenous hemisphere used in similar experiments in the past. Strong boosters and an upward charge detonation scheme were applied to provide more energy radiated to the atmosphere. Under these conditions the evaluation of the actual explosion yield, an important source parameter, is crucial for the GT0 calibration experiment. Audio-visual, air-shock and acoustic records were utilized for interpretation of observed unique blast effects, and for determination of blast wave parameters suited for yield estimation and the associated relationships. High-pressure gauges were deployed at 100–600 m to record air-blast properties, evaluate the efficiency of the charge design and energy generation, and provide a reliable estimation of the charge yield. The yield estimators, based on empirical scaled relations for well-known basic air-blast parameters—the peak pressure, impulse and positive phase duration, as well as on the crater dimensions and seismic magnitudes, were analyzed. A novel empirical scaled relationship for the little-known secondary shock delay was developed, consistent for broad ranges of ANFO charges and distances, which facilitates using this stable and reliable air-blast parameter as a new potential yield estimator. The delay data of the 2009 shot with IMI explosives, characterized by much higher detonation velocity, are clearly separated from ANFO data, thus indicating a dependence on explosive type. This unique dual Sayarim explosion experiment (August 2009/January 2011), with the strongest GT0 sources since the establishment of the IMS network, clearly demonstrated the most favorable westward/eastward infrasound propagation up to 3,400/6,250 km according to appropriate summer/winter weather pattern and stratospheric wind directions, respectively, and thus verified empirically common models of infrasound propagation in the atmosphere. 相似文献
18.
The South Ural meteoroid (February 15, 2013; near the city of Chelyabinsk) is undoubtedly the best documented meteoroid in history. Its passage through the atmosphere has been recorded on videos and photographs, visually by observers, with ground-based infrasound microphones and seismographs, and by satellites in orbit. In this work, the results are presented of an analysis of the transionospheric GPS sounding data collected in the vicinity of the South Ural meteoroid site, which show a weak ionospheric effect. The ionospheric disturbances are found to be asymmetric about the explosion epicenter. The received signals are compared, both in shape and amplitude, with the reported ionospheric effects of ground level explosions with radio diagnostics. It is shown that the confident registration of ionospheric effects as acoustic gravity waves (AGWs) by means of vertical sounding and GPS technologies for ground explosions in the range of 0.26–0.6 kt casts doubt on the existing TNT equivalent estimates (up to 500 kt) for the Chelyabinsk event. The absence of effects in the magnetic field and in the ionosphere far zone at distances of 1500–2000 km from the superbolide explosion epicenter also raises a question about the possibility of an overestimated TNT equivalent. An alternative explanation is to consider the superposition of a cylindrical ballistic wave (due to the hypersonic motion of the meteoroid) with spherical shock waves caused by the multiple time points of fragmentation (multiple explosions) of the superbolide as a resulting source of the AGW impact on ionospheric layers. 相似文献
19.
Application of Network-averaged Teleseismic P-wave Spectra to Seismic Yield Estimation of Underground Nuclear Explosions 总被引：1，自引：0，他引：1
—?A set of procedures is described for estimating network-averaged teleseismic P-wave spectra for underground nuclear explosions and for analytically inverting these spectra to obtain estimates of m b /yield relations and individual yields for explosions at previously uncalibrated test sites. These procedures are then applied to the analyses of explosions at the former Soviet test sites at Shagan River, Degelen Mountain, Novaya Zemlya and Azgir, as well as at the French Sahara, U.S. Amchitka and Chinese Lop Nor test sites. It is demonstrated that the resulting seismic estimates of explosion yield and m b /yield relations are remarkably consistent with a variety of other available information for a number of these test sites. These results lead us to conclude that the network-averaged teleseismic P-wave spectra provide considerably more diagnostic information regarding the explosion seismic source than do the corresponding narrowband magnitude measures such as m b , M s and m b (L g ), and, therefore, that they are to be preferred for applications to seismic yield estimation for explosions at previously uncalibrated test sites. 相似文献
20.
A. S. Cherepantsev V. A. Saltykov Yu. A. Kugaenko P. V. Voropaev 《Seismic Instruments》2018,54(1):17-27
The possibility of registering high-frequency seismic noise in a broadband frequency range (f = 5–400 Hz) has been considered. The use of an accelerometer on based on the S mode of bending vibrations increases the sensitivity and expanses the frequency range. The operating principle of the accelerometer and its main technical characteristics have been described. Pilot registration of seismic noise was organized at Nachiki seismic station in Kamchatka. The comparative results of tidal effects in seismic noise have been presented according to the data of the broadband accelerometer (f = 5–400 Hz) and resonance sensor (f0 = 30 Hz) during long-term registration on a common base. 相似文献