Variation of the Load/Unload Response Ratio Before the Main Shocks of the Reservoir-Induced Earthquakes

In this paper, the theory of the load/unload response ratio is applied to the prediction of the reservoir-induced earthquakes, and variation of the load/unload response ratio Y preceding the occurrence of main shocks of the reservoir-induced earthquakes in Xinfengjiang, Foziling, Danjiangkou, and Shenwo. The results show that the load/unload response ratio Y rises evidently prior to the main shocks.     

Application of Load/Unload Response Ratio in the Study of Seismicity in the Region of Iran

The variation of Load/Unload Response Ratio (LURR) against time for earthquakes in Kerman Province, Iran, on February 22, 2005, M6.4 and in Lorestan Province, Iran, on March 31, 2006, M6.1, has been calculated and analysed in this paper. The tempo-spatial scanning of LURR in the region of Iran during January 1, 2003 to March 31, 2006 has been conducted, with 1 year as a time-window, 1 month as a time-step, and the comparison of the LURR anomalous regions in 2004 with the actual earthquakes with M≥5.0 in the next year (2005) is also given, which shows that 11 earthquakes with M≥5.0 occurred in LURR anomalous regions while 12 earthquakes with M≥5.0 in LURR regions in 2005. Furthermore, the seismicity in this region is studied by investigating the evolvement of the anomalous LURR regions.     

Experimental Research on the Load／Unload Response Ratio （LURR） Theory

Implementing acoustic emission experiments with large rock samples, LURR (Load/Unload Response Ratio) theory was studied. The loading conditions in the experiments were designed to simulate the complicated loading process of underground rocks. The damages emerging inside the rock samples were recorded by the acoustic emission technique during the loading process. The experimental results were consistent with prediction by LURR theory. Integrating the changing processes of LURR value Y and the location process of acoustic emission events showed agreement between the variation of LURR value Y and the damage evolution inside the rocks. Furthermore, the high value of Y emerged before the complete breakdown of materials. Therefore, the damage evolution of rock specimen can be quantitatively analyzed with LURR theory, thus the failure of the rock materials and the earthquake occurrence may be predicted. The experimental results gave a further verification of LURR theory.     

The Natural Probability Distribution of Load and Unload Response Ratio

In this paper,the Gutenberg-Richter model is used to generate seismic events.The events that satisfy the random distribution are also generated.With those events,the natural probability distribution of Load and Unload Response Ratio(LURR),which measures quantitatively the degree of instability of a nonlinear system,is discussed.The study is based on stress energy release,which is chosen as the response of nonlinear system F3.The comparative results from the observation catalogue and generating data are also studied.It is revealed that the natural probability of LURR is mostly stable when the sample number is sufficient.The lower the natural probability of LURR,the more the precursory is information it may contain.The influence of Y3 resulting from the sample number and the magnitude range of events is also discussed.     

Investigation on the Load/Unload Response Ratio With Coda Q-1 as Response

The load/unload response ratio YQ with the geophysical parameter coda Q-1 of the crust as response is denned in this study.The variation in YQ-1 before and after the Northridge earthquake of January 17,1994(California)has been investigated by using the data of coda Q-1 with frequencies of 1.5,3.0,6.0,12.0,and 24.0 Hz in the Southern California from 1987 to 1994.It can be found that YQ-1 for coda waves with all frequencies,the frequency of 12.0 Hz excluded,ascended to a certain extent prior to the occurrence of the rnainshock and returned to normality after the main shock.     

The Time-Space Features of Ms≥6.0 Earthquakes Subsequent to Ms≥7.0 Earthquakes in the Mainland of China

In this paper,the time-space features of Ms≥6.0 strong earthquakes that have occurred on the Chinese mainland since the beginning of this century were analyzed; the effect of Ms≥7.0 large shocks in mitigating Ms≥6.0 strong earthquakes subsequent to them vas studied both temporally and spatially; and the accumulative probabilities for the occurrence of Ms≥6.0 strong earthquakes subsequent to Ms≥7.0 large shocks were calculated.The results seem to imply that the effect of Ms≥7.0 large shocks in mitigating subsequent strong events is relatively obvious within certain time-space ranges.This is because the strain energy accumulated over a long time in the region around the source has been mostly released through the fracture produced by the large shock,the possibility for another large fracture to occur again in the same region within a certain period of time has been greatly reduced and therefore the probability for subsequent strong earthquakes to occur in that region is very low.These results can be     

Sketch of Epicentral Distribution of Positive and Negative Earthquake and Its Application to the Response Ratio Theory

INTRODUCTION It is common knowledge that the development and occurrence of an earthquake is a very complicated geophysical process. An earthquake is caused by the local failure of the earth crust medium, and earthquakes are distributed inhomogeneously in space. Seismic activities, however, are a real reflection of the interaction of the faults, which provides us some information concerning the earth crust medium and may help us predict the earthquake. Therefore, the study of the seismicity pattern can become a means of earthquake prediction. In order to reflect directly the spacial distribution of seismic activities, the sketch of epicentral distribution has been widety used in the study     

Earthquake Activity Features Before Earthquakes with Ms ≥ 7.0 in the Central-Northern QinghaiXizang (Tibet) Block

We have studied the seismicity features of M_S≥5.0 earthquakes two years before strong earthquakes with M_S≥7.0 occurred in the central-northern Qinghai-Xizang (Tibet) block since 1920. The results have showed that there is an obvious gap or quiescence of M_S5.0～6.9 earthquakes near epicenters. We have also studied statistical seismicity parameters of M_S5.0～6.9 earthquakes in the same region since 1950. The results have showed that earthquakes with M_S≥7.0 occurred when earthquake frequency is relatively high and earthquake time, space accumulation degrees are rising. And the prediction effect R value scores are between 0.4～0.7. We have concluded that, before earthquakes with M_S≥7.0 in the central-northern Qinghai-Xizang (Tibet) block, M_S5.0～6.0 earthquake activity in the whole area increased and accumulated in time and space, but earthquakes with M_S≥7.0 occurred where M_S5.0～6.0 earthquake activity was relatively quiet.     

Possibility of Application of the Electromagnetic Missile Theory to Earthquake Prediction

Geoeiectromagnetic signals related to earthquakes have been detected in China and many other countries.Problems concerning the mechanism of the electromagnetic emission and transportation still remain unsolved,although several models have been proposed.We consider that the theory of "electromagnetic missile emission" may be used to solve this problem,and thus develops the basic ideal of the Electro Magnetic Missile Emission(EMME)model of the emission of electromagnetic signals before earthquakes:pulse variation of the stress state causes the emission of electrons,or sudden flow of the fluid,in a certain direction along or near the fault which is located at the focus of an earthquake,forming a pulse electric current; this current accordingly produces a kind of slowly attenuated EM Wave(electromagnetic missile,which may be observed on the surface of the earth)in the perpendicular direction.In other directions these EM waves vanish quickly and cannot reach ground level.     

Study on the Relationship Between Recent Crustal Deformation and the Temporal-Spatial Distribution of Strong Earthquakes ( Ms ≥6.0) in the Sichuan-Yunnan Region

Analysis of deformation data measured across the faults, regional vertical deformation data and GPS measurements in the Sichuan-Yunnan region made since the 1980s permitted us to conclude that the crustal deformation in the region during this period of time was relatively weak and caused the occurrence of earthquakes (Ms≥6.0), which were not distributed along the major boundary active faults in the region after the 1981 I)awu Ms 6.9 earthquake and that the seismic activity is characterized by quasi-clockwise migration. Thus, it follows that earthquake prediction research should be focused on the central part of the Sichuan-Yunnan region in the coming years. Finally, a concept of temporal division of the region into active blocks is suggested and the preliminary result of the division is given in the paper.     

Brief Introduction to the "Catalogue of Recent Chinese Earthquakes (1912～1990, M_S≥4.7)

This paper briefly introduces the principles and methods for compiling the "Catalog of Recent Chinese Earthquakes (1912 ～ 1990, MS≥4.7)." This new catalog is compiled by revising and supplementing the 1983 version of the Catalog of Chinese Earthquakes.     

Deterministic Variability of the Ionosphere on the Eve of Strong (M ≥ 6) Earthquakes in the Regions of Greece and Italy According to Long-Term Measurements Data

Geomagnetism and Aeronomy - Abstract—Specific features of the variation in the electron concentration in the ionosphere in front of strong (M ≥ 6) earthquakes in the most seismically...     

Theory and Experimental Results about the Application of Remote Sensing to Earthquake Prediction

In this paper,the theory for applying remote sensing to earthquake prediction has been elucidated and an experiment has been made.Through the experiment,it has been found that the characteristics and temperature of infrared radiant of rocks vary as a function of rock stress,the order of magnitude of radiance variation is 10-5(W/cm2 sr um),the amount of variation of the radiant temperature is 0.2℃~0.8℃ and some significant precursor information has been discovered.The experiment has verified preliminarily that the advanced technology of remote sensing can be applied to earthquake prediction.     

Faulting Processes of Historic (1917–1962) M = 6.0 Earthquakes Along the North-central Caribbean Margin

—The plate boundary along the north-central Caribbean margin is geologically complex. Our understanding of this complexity is hampered by the fact that plate motions are relatively slow (1 to 2 cm/yr), so that recent seismicity often does not provide a complete picture of tectonic deformation. Studies of the faulting processes of instrumentally recorded earthquakes occurring prior to 1962 thus provide important information regarding the nature and rate of seismic deformation within the region, and are essential for a comprehensive assessment of seismic hazard. We have conducted body waveform modeling studies of eight earthquakes which occurred along the north-central Caribbean plate margin, extending from southeastern Cuba to the Swan Island fracture zone (75 to 83°W). None of these earthquakes has been previously studied and several occurred in regions where no recent (post-1962) seismicity has been recorded. The plate margin in the western portion of our study area is characterized by a transform fault-spreading center system. In the central and eastern portions of our study area the plate margin is a complex, diffuse region of deformation that couples transform motion in the Cayman trough to subduction along the Lesser Antilles arc. Our results show that the western portion of the study area has only experienced large strike-slip earthquakes. Off southeastern Cuba two earthquakes appear to have occurred on high angle, northward dipping, reverse faults with south to southeastward directed slip vectors. An earthquake in northern Jamaica in 1957 shows pure strike-slip faulting, most likely along an east-west trending fault. Finally, an unusual sequence of events located in the Pedro Bank region ~70 km southwest of Jamaica has a mainshock with a reverse-oblique mechanism, suggesting continuity of the plate interface stress field well south of the northern Caribbean margin.     

加卸载响应比(Load/Unload ResponseRatio)、能量加速释放(AE/MR)的临界区尺度及地震预测

加卸载响应比理论的主要思路是：系统在稳定状态时加载响应与卸载响应的比值与非稳定状态时加载响应与卸载响应的比值是完全不同的。大震前加卸载响应比升高和能量加速释放这两种现象可以用来对地震进行中期预报。同时，加卸载响应比理论和能量加速释放可能有相同的物理机制。为了验证这种地震预报方法的可行性，我们研究了几例发生在澳大利亚与中国，M5．0～7．9之间的地震，其中包括破坏严重的澳大利亚纽卡斯尔地震和中国的唐山地震。我们利用以震源中心一定范围内的数据计算了震前的加卸载响应比和能量加速释放的幂律拟合。能量幂律加速释放存在一组最佳的拟合，一定范围内加卸载响应比达最大值表明加卸载响应比也有一个临界区尺度。进一步讲，加卸载响应比与能量加速释放的临界区尺度是相似的。这些结果表明加卸载响应比与能量加速释放有相同的物理机制。进一步的研究可能会对这种物理机制提供更好的解释，同时也能对地震的中期预报提供理论基础。     

Tsunami Mapping Related to Local Earthquakes on the French–Italian Riviera (Western Mediterranean)

The Ligurian coast, located at the French–Italian border, is densely populated as well as a touristic area. It is also a location where earthquakes and underwater landslides are recurrent. The nature of the local tsunamigenesis is therefore a legitimate question, because no tsunami warning system can resolve tsunami arrival times of a few minutes, which is the case for the area. As far as the seismicity of the area is concerned, the frequent recurrent earthquakes are generally of moderate magnitude: most of them are lower than M _w 5. However, the relatively large M _w 6.9 earthquake (Larroque et al., in Geophys J Int, 2012. doi:10.1111/j.1365-246X.2012.05498.x) that occurred on the February 23, 1887, offshore of Imperia (Italian Riviera) is quite emblematic. This unusual event for the region merits a complete study: the quantification of its rupture mechanism is essential (1) to understand the regional active deformation, but also (2) to evaluate its tsunamigenesis potential by deriving relevant rupture scenarios obtained from our knowledge of the event; for that purpose the event is extensively described here. The first point has been the subject of quite a few studies based on the seismotectonics of the area. The last documented approach has been completed by Larroque et al. (Geophys J Int, 2012. doi:10.1111/j.1365-246X.2012.05498.x) who proposed a rupture scenario involving a reverse faulting along a north dipping fault and favoring a M _w 6.9 magnitude. In the present paper (1) we study the accuracy of their solutions in relation to the computational grid spacing and the dispersive/nondispersive parameterization, (2) based on an uncertainty on the recorded wave amplitude of the Genoa tide gauge they used, we propose a M _w 6.7 earthquake magnitude solution for the event (the kinematics is unchanged), co-existing with the M _w 6.9, (3) we evaluate the tsunami coastal impact of the 1887 event, and (4) we test a range of possible ruptures that local faults may undergo in order to propose a synoptic mapping of the tsunami threat in the area. The spatial distribution of the maximum wave height (MWH) is provided with a tentative identification of the processes that are responsible for it. This latter issue is imperative in order to make our mapping as generic as possible in the framework of our deterministic approach (based on realistic scenarios and not on ensemble statistics). The predictions suggest that the wave impact is mostly local, considering the relatively moderate size of the rupture planes. Although the present-day seismicity in this region is moderate, stronger earthquakes (M > 6.5) have occurred in the past. The studied scenarios show that for such events specific localities along the French–Italian Riviera may experience very significant MWH related to the shallow focal depth tested for such scenarios. We may reasonably conclude that the tsunami threat is relatively significant and uniform at the Italian side of the Riviera (from Ventimiglia to Imperia), while it is more localized (sporadic) at the French side from Antibes to Menton with, however, higher local level of inundation, e.g., Nice city center.     

Source mechanism of strong aftershocks (M_s≥5.6) of the 2008/05/12 Wenchuan earthquake and the implication for seismotectonics

Dozens of >M5, hundreds of >M4, and much more >M3 aftershocks occurred after the 2008/05/12 Wenchuan earthquake, which were well recorded by permanent and portable seismic stations. After relocated with P arrival, the >M3 aftershocks show two trends of distribution, with most of the aftershocks located along the north-east strike consistent with Longmenshan fault system, yet there is a north-west trend around the epicenter. It seems that substantially more aftershocks occur in regions with crystalline bedro...     

Source processes of large (M≥6.5) earthquakes of the Southeastern Caribbean (1926–1960)

We have conducted body waveform modeling studies of 13 historic earthquakes to provide a better understanding of the long-term spatial and temporal pattern of seismicity and deformation within a region extending from Barbuda, Lesser Antilles, to Cumana, Venezuela. Our results suggest that shallow earthquakes (<50 km deep) along the South American-Caribbean plate margin reflect right-lateral and extensional deformation. Intermediate depth events (100 km) show left-lateral strike-slip motion beneath the Paria peninsula of Venezuela. In the Lesser Antilles the 1960 Barbuda and 1946 Martinique earthquakes appear to be interplate thrust events, however the greatest moment release in the region has occurred at intermediate depths as a mixture of normal and strike-slip faulting, generally along trends oblique to the arc. The deformation rate estimated from the seismic moment release between 1926 and 1960 is only 1 to 10% of the estimated plate convergence rate for the region.     

Study on Variation of Fitting Goodness of Relation Between Earthquake Frequency and Magnitude before Moderately Strong Earthquakes (Ms≥5.0)

In this paper,characteristics of spatial and temporal variation of linear fitting goodness before some moderately strong earthquakes(Ms≥5.0)in the eastern part of China(east of longitude 180)are studied according to the famous Gutenberg-Richter's relation expressed as lgN=a-bM,by using the moderate and small events that occurred in and around the source area.The results show that the linear goodness of fitting varies abnormally prior to these moderately strong earthquakes.In the early stage of the earthquake preparatory process,distribution of the energy released through small events in and around the source area is isostatic and the fitting goodness approximates 1,while the distribution of the energy turns to be isostatic before moderately strong earthquakes,leading to the obvious decrease of the linear goodness of fitting.This phenomenon could be a medium term anomaly and a medium term criterion for moderately strong earthquake prediction.     

Identifying the precursors of large (M ≥ 6.0) earthquakes in Kamchatka based on data from the Kamchatka Branch of the Russian expert council on earthquake prediction: 1998–2011

This paper describes the activities of the Kamchatka Branch of the Russian Expert Council on Earthquake Prediction, Assessment of Seismic Hazard and Risk (KB REC) over a 14 year period. We provide brief information on how the KB REC functions, the methods that are used for earthquake prediction in expert assessments, forecasts, and precursors of M ≥ 6.0 Kamchatka earthquakes for the 1998–2011 period. The efficiency of prediction using several methods is estimated.