Term Earthquake Prediction Research Articles

The dynamics of the stress state in Southern California based on the geomechanical model and current seismicity: Short term earthquake prediction

The dynamics of the stress state in Southern California based on the geomechanical model and current seismicity: Short term earthquake prediction

CORRELATIONS OF THE MEAN TIME AND MEAN MAGNITUDE OF ACCELERATING PRESHOCKS WITH THE ORIGIN TIME AND MAGNITUDE OF MAINSHOCK

Forty-five preshock sequences preceding corresponding strong (M≥6.4) mainshocks which occurred recently (since 1980) in a variety of seismotectonic regimes (W. Mediterranean, Aegean, Anatolia, California, Japan, Central Asia, South America) have been examined to identify new predictive properties. It has been observed that the mean origin time, , and the mean magnitude, of the accelerating preshocks of each sequence are correlated with the origin time, tc, and the magnitude, M, of the mainshock, respectively. The following relations have been derived: where sa (in Joule ½ /yr.104 Km2 ) is the Benioff strain rate in each preshock (critical) region and σ is the corresponding standard deviation. The possibility for using these relations as constraints in attempts for intermediate term earthquake prediction is discussed.

INTERMEDIATE TERM EARTHQUAKE PREDICTION BASED ON INTEREVENT TIMES OF MAINSHOCKS AND ON SEISMIC TRIGGERING

Two models, which contribute to the knowledge on intermediate term earthquake prediction are further examined, improved and applied. The first of these models, called Time and Magnitude Predictable (TIMAP) regional model is based on repeat times of mainshocks generated by tectonic loading on a network of faults which are located in a certain seismic region (faults’ region). The second model, called Decelerating-Accelerating Strain (D-AS) model, is based on triggering of a mainshock by its preshocks. Parameters of the TIMAP model have been specified for the Aegean area and applied by a backward test in 86 circular faults’ regions of this area. The test shows the validity of this time dependent model with 29% false alarms. Data concerning decelerating and accelerating seismic (Benioff) strain, which preceded 46 strong (M≥6.3) recent mainshocks in a variety of global seismotectonic regimes, show that the generation of a mainshock is triggered by quasi-static stress changes due to accelerating preshocks which occur in a broad (critical) region and by static stress changes due to the large number (frequency of occurrence) of small preshocks generated in a narrow (seismogenic) region. Retrospective predictions (postdictions) of these 46 mainshocks by the D–AS model confirms previous results concerning the prediction uncertainties (2σ) of the model in the origin time (± 2.5 years), epicenter location (≤ 150 km) and magnitude (± 0.4) of an ensuing mainshock with a probability ~ 80%. Information is also given on the successful prediction by the D-AS model of: 1) the Cythera strong (M = 6.9) earthquake which occurred on 8 January 2006 in the southwestern part of the Hellenic Arc and 2) of the Rhodes strong (M = 6.4) earthquake which occurred on 15 July 2008 in the Eastern part of this Arc. A backward combined application of both models in the Aegean area shows an uncertainty ≤120km in the epicenter location of an ensuing mainshock.

Paleo Earthquake Analysis for Sumatra Region in Order to Forewarn the Possible Occurrence of Future Earthquake

By analysing the previous earthquakes in Sumatra region the long term earthquake prediction may help the Government and NGOs for necessary emergency preparedness. In order to predict chaotic behaviour of nature K-Means clustering algorithm is employed over the previous earthquake data for clustering the regions based on the coordinates of the earthquakes occurred places and Laws of Haversine is used further to compute the distance between the main earthquakes and secondary shocks. The 14 years of earthquake data of 8400 samples were collected from various sources. Each cluster results in different radius of the cluster. Based on the laws of Haversine results the data were loaded and analysed. The analysis results show the pattern of earthquakes and its changes. It gives the information about next larger earthquake pattern and place of occurrence.

Variations of b-values preceding large earthquakes in the Andaman–Sumatra subduction zone

Fifteen largest earthquakes, Mw⩾7, occurring between 2000 and 2010 in the Andaman–Sumatra region are studied. The available USGS list of events used is complete for a threshold magnitude Mc=4.5 and contains 6973 shocks. Spatial and temporal variation of b-values, in the Gutenberg–Richter formula log N=a−bM, was investigated in six selected epicentral regions. The technique of moving spatial- and time-windows was applied. Deduced b-values show large variations from 0.55 to 2.40. The 15 largest events all took place within regions of low b and were preceded by significant drops in b-values. Observed correspondence between low b and the occurrence of large earthquakes suggests that b(t) has a potential which could be employed in a medium term (months, years) earthquake prediction.

Comment on "Seismomagnetic Effects from the Long-Awaited 28 September 2004 M 6.0 Parkfield Earthquake" by M. J. S. Johnston, Y. Sasai, G. D. Egbert, and R. J. Mueller

We present some comments on two issues dealt with in Johnston et al. (2006), which reported that there were no electric and magnetic (EM) precursors for the 28 September 2004 M 6.0 Parkfield earthquake (EQ). The first comment is on their introduction, which, while raising critical comments on seismic electric signals (SESs) in Greece and Japan, concluded that useful prediction of EQs seems unlikely using electromagnetic data. We show point by point that their criticism is unfounded. The second comment is on their assertion of the nonexistence of SESs at Parkfield. We point out that this assertion may be premature as their efforts to identify signals appear insufficient. They show, in a timescale too coarse to recognize SESs, only band-passed magnetic and electric data for the five day period before the Parkfield EQ, which is much too short. Even if the claimed nonexistence of an electric precursor is demonstrated by further data analysis, the probability will remain that their single observation site was insensitive to SESs. They apparently have made no search effort for SES sensitive sites. Our experiences show that SES insensitive sites are not uncommon even near epicenters. On these grounds, their overall negative attitude on electromagnetic methods seems much too premature and inappropriate. Even if no EM precursors were generated for the Parkfield EQ, we suggest it would be more scientifically sound to seek the physical reason for it before negating SESs in general, which have been well observed elsewhere. Johnston et al. (2006) (J2006, hereafter), in their introduction, list four reasons for doubting the observations of SESs in Greece and Japan. Although this portion seems to have rather little to do with their own work, it demonstrates their basic negative stance against the VAN method (which is a method for short term earthquake prediction by monitoring …

EARTHQUAKE PREDICTION IN THE AREA OF N. EVIA ON THE BASIS OF GROUNDWATER RADON CONCENTRATION CHANGES

Significant changes in the groundwater radon concentration, were observed on the 29/7/2003, at Kammena Vourla. The radon concentration changes can be attributed to the temporary enrichment of the groundwater by radon from the surrounding rocks due to the action of stress release or stress accumulation prior an earthquake. EPPO was immediately informed for the existence of these changes. On the 3/8/2003, a significant number of earthquakes in Northern Evia were recorded in an interval of a few hours. The epicentres of the earthquakes were located in the conceivable line between the epicentre of the strong earthquake of Skyros island (July 2001) and the site of the station of radon measurement at Kammena Vourla, on the extension of the Northern Aegean fault. In the 23/1/2003, in the same station, 3 significant changes of radon concentration were measured EPPO was immediately informed for impending seismic activity in Northern Evia. On the 29th of January three earthquakes were recorded. Their epicentres were located in N. Evia, close to the radon measurement, station. On the 2/2/2003, a new significant radon change occurred at Kammena Vourla followed by an earthquake (7/2/2003). In the 12/2/2003 in a letter that we addressed to the EPPO administration, the beginning of a new radon change was reported which also led to an earthquake with the same epicentre. The changes that are recorded in the system of radon measurement of Kammena Vourla are precursors of earthquakes, related to the extension of the N. Aegean fault towards the Sterea Hellas and have their epicentre in N. Evia. It seems that the method can be an important tool for local, short term earthquake prediction.

Thử nghiệm dự báo động đất dài hạn theo quy luật hoạt động tiền chấn

The test of long term earthquake prediction by using foreshock activity manifestation

Beno Gutenberg contribution to seismic hazard assessment and recent progress in the European–Mediterranean region

The fundamental work of Beno Gutenberg has inspired and guided an appreciable part of research in modern seismology, both from the experimental and the theoretical point of view. Among the several topics of seismology that have benefited from the fundamental contribution of Gutenberg, we consider particularly relevant the description of the asthenospheric low-velocity channel, the definition of the surface waves magnitude and the Gutenberg–Richter law, since they are pivotal tools for seismic hazard assessment. The quite revolutionary model for the lithosphere–asthenosphere system in the European area predicts the existence of almost aseismic lithospheric roots. These roots are located in correspondence of most of the orogenic belts and interrupt the asthenosphere low velocity channel that has been identified by Beno Gutenberg in 1948. The model of the European upper mantle, proposed for the first time in 1979 and subsequently refined, has stimulated a considerable amount of research, which has nicely confirmed the major innovative features of the early model. At present, the subduction of the lithosphere at continent–continent collisions, supported not only by seismological data, is a widely accepted concept within the community of Earth scientists, even if it contradicts one of the basic dogmas of the original formulation of plate tectonics. The proposed model for the Alpine–Apennines area supplies a new and unifying framework for the interpretation of the Quaternary magmatism, at present generally accepted by petrologists and geochemists. The theoretical basis for the Gutenberg's surface-wave magnitude calibration function has been supplied by the use of complete synthetic seismograms, and thus it has been possible to formulate the theoretical M S depth correction. The introduction of the depth correction for M S enables the computation of surface wave magnitude for all earthquakes, regardless of their focal depth. This is especially important for the quantification of subcrustal historical earthquakes, for which the seismic moment may be difficult to estimate from recordings of early mechanical seismographs. The new M S calibrating function yield both distance- and depth-independent magnitude estimates. The analysis of the global seismicity, using the seismotectonic regionalization in subduction zones, mid oceanic ridge zones, island arcs, shows that a single Gutenberg–Richter (GR) relation is not universally applicable and that a multiscale seismicity model can reconcile two apparently conflicting paradigms: the Self-Organized Criticality mechanism and the Characteristic Earthquake concept. The multiscale representation has been applied to Italy, where the zones at the space scale of 400–500 km quite well reproduce the shapes of the regions used to apply the, globally tested, CN intermediate term earthquake prediction algorithm.

Seismic pattern treatment method through calculation of seismic density at grid nodes

Analysis of seismic data and seismicity characteristics in China, we gave a method to deal with seismic patterns by calculating density at grid nodes. Number of earthquakes and epicenter distribution are considered comprehensively in this method. Effect of datum accuracy is stressed on parameter confirmation. Seismic patterns from this method are stable and can reflect seismic characteristics reliably. These seismic patterns are the base of quantitative analysis of seismicity. It can be applied in seismic tendency analysis and medium-long term earthquake prediction, earthquake countermeasure and risk mitigation.

Colliding cascades model for earthquake prediction

A wide set of premonitory seismicity patterns is reproduced on a numerical model of seismicity, and their performance in prediction of major earthquakes is evaluated. Seismicity is generated by the Colliding Cascades Model, recently developed by the same authors. The model has a hierarchical structure. It describes the interaction of two cascades: a direct cascade of loading, which is applied to the top (largest) element and transfers down the hierarchy, and inverse cascade of failures, which goes up the hierarchy, from smaller to larger elements. These cascades collide and interact: loading leads to failures, while failures release and redistribute the loading. Three basic types of earthquake precursors are considered. They reflect the following integral characteristics of seismicity: (i) the clustering of earthquakes in space and time, (ii) the intensity of earthquake sequences, and (iii) the correlation distance between earthquakes. Patterns of the first two types were established mainly by the analysis of observations and are used in the intermediate term earthquake prediction algorithms with a characteristic duration of the alarm of a few years. These patterns are validated by advance earthquake prediction. Patterns of the third type have been found very recently in the Colliding Cascades Model, though they were hypothesized previously. They have yet to be validated by observations of real seismicity. For each precursor, we explore what is called an “error diagram” showing the total duration of alarms, the rate of failures to predict, and the rate of false alarms

Nonlinear magnitude frequency relation and two types of seismicity systems

A nonlinear magnitude frequency equation has been derived in this paper on the assumption that all seismicity systems hold fractal characteristics, and according to the differences of relevant coefficients in the equation, seismicity systems are classified into two types: type I, the whole earthquake activity is controlled by only one great unified system; type II, the whole earthquake activity is controlled by more than one great system. One type of seismicity system may convert to the other type, generally. For example, a type I system will change to a type II system prior to the occurrence of a strong earthquake in North China. This change can be regarded as an index for earthquake trend estimation. In addition, the difference between b value in nonlinear magnitude frequency equation and that in linear equation and the term dΔM related to the coefficients of nonlinear terms obtained in this paper are proved to be a pair of available parameters for medium short term earthquake prediction.

Electrical streaming potential precursors to catastrophic earthquakes in China

The majority of anomalies in self-potential at 7 stations within 160 km from the epicentre showed a similar pattern of rapid onset and slow decay during and before the M 7.8 Tangshan earthquake of 1976. Considering that some of these anomalies associated with episodical spouting from boreholes or the increase in pore pressure in wells, observed anomalies are streaming potential generated by local events of sudden movements and diffusion process of high-pressure fluid in parallel faults. These transient events triggered by tidal forces exhibited a periodic nature and the statistical phenomenon to migrate towards the epicentre about one month before the earthquake. As a result of events, the pore pressure reached its final equilibrium state and was higher than that in the initial state in a large enough section of the fault region. Consequently, local effective shear strength of the material in the fault zone decreased and finally the catastrophic earthquake was induced. Similar phenomena also occurred one month before the M 7.3 Haichen earthquake of 1975. Therefore, a short term earthquake prediction can be made by electrical measurements, which are the kind of geophysical measurements most closely related to pore fluid behaviors of the deep crust.

Seismotectonic models and CN algorithm: The case of Italy

The CN algorithm is utilized here both for the intermediate term earthquake prediction and to validate the seismotectonic model of the Italian territory. Using the results of the analysis, made through the CN algorithm and taking into account the seismotectonic model, three main areas, one for Northern Italy, one for Central Italy and one for Southern Italy, are defined. Two transition areas between the three main areas are delineated. The earthquakes which occurred in these two areas contribute to the precursor phenomena identified by the CN algorithm in each main area.

Long Term Earthquake Prediction in the New Guinea-Bismarck Sea Region Based on the Time and Magnitude Predictable Model.

The New Guinea-Bismarck Sea region has been divided into 17 seismogenic sources on the basis of certain seismological and geomorphological criteria. In each of these sources the interevent times between successive main shocks with magnitudes equal to or larger than certain cut-off magnitudes were considered. These interevent times as well as the magnitudes of the main shocks have been used to determine the following relations: log Tt = 0.36Mmin + 0.28Mp - 0.49 logMo + 9.58, ME = 0.74Mmin-0.31Mp+0.49logMo-8.53, where Tt is the calculated interevent time measured in years, Mmin is the magnitude of the smallest main shock considered, Mp and ME are the magnitudes of the preceding and the expected main shocks and Mo is the yearly released seismic moment in each source. On the basis of these relations and considering the date and the magnitude of the last main shock, conditional probabilities for the next 10 years (1993-2002) and the magnitude of the expected main shock in each source were determined.

Recent advances in the research on seismo-electromagnetic emissions

The paper briefly reviews the recent advances and the main trend, as well as the major subjects for future study in the research on seismo-electromagnetic emissions. The preliminary results obtained show that the recently discovered electromagnetic emission phenomena prior to earthquake events are objective facts and may be prospective precursor applicable for short term earthquake prediction. Considering the complexity of the generation mechanisms, as well as the space coupling and the time variation processes of the seismo-electromagnetic emissions, we must deeply study the essential connection between the precursory emission phenomena and the seismogenic processes. Closely connect the field observations and theoretical research and try to comprehensively diagnose by correlating with other precursors.

Intermediate term earthquake prediction in the area of Greece: application of the algorithm M8 : Latoussakis, J; Kossobokov, V G Pure Appl GeophysV134, N2, Sept 1990, P261–282

Intermediate term earthquake prediction in the area of Greece: application of the algorithm M8 : Latoussakis, J; Kossobokov, V G Pure Appl GeophysV134, N2, Sept 1990, P261–282

Intermediate term earthquake prediction in the area of Greece: Application of the algorithm M8

The 3 strongest earthquakes,M≥7.0, which have occurred since 1973 in the area of Greece were preceded by a specific increase of the earthquake activity in the lower magnitude range. This activation is depicted by algorithm M8. This algorithm of intermediate term earthquake prediction was originally designed for diagnosis by Times of Increased Probability (TIPs) of the strongest earthquake,M≥8.0 worldwide (Keilis-Borok andKossobokov, 1984). At present the algorithm is retrospectively tested for smaller magnitudes in different seismic regions (Keilis-Borok andKossobokov, 1986, 1988). A TIP refers to a time period of 5 years and an area whose linear size is proportional and several times larger than that of the incipient earthquake source. Altogether the TIPs diagnosed by the algorithm M8 in the area of Greece occupy less than 20% and the Times of Expectation (TEs) about 10% of the total space-time domain considered. Also there is a current TIP for the southeastern Aegean sea and 1988–1992. It may specify the long-term prediction given inWyss andBaer (1981a,b).

Should we try to predict the next great U.S. earthquake?

Short term earthquake prediction has become technically possible. However, the desirability of such predictions depends both on the probability of successfully predicting an event and on the odds of false predictions. This paper investigates the economic feasibility of earthquake prediction as a function of program performance for the Los Angeles area. Based on the now increasing probability of a great earthquake in the region, the paper concludes that, given current best estimates of program performance, such predictions may well provide expected benefits which exceed expected casts.

Stress transfer and nonlinear stress accumulation at subduction-type plate boundaries ? Application to the Aleutians

A study of stress accumulation in seismic gaps and of stress transfer along linear plate boundaries is presented. Time-dependent reloading of plate boundaries following seismic ruptures is modeled by a modified Elsasser model of a coupled lithosphere/asthenosphere plate system. This model is applied to study a series of large earthquakes in the Aleutian Islands and the Alaska peninsula in 1938–1965. It is found that the Rat Island earthquake and the 1948 earthquake in the central Aleutians are likely to have been triggered by adjacent ruptures, in the sense that their occurrence would have come at a later time had their neighboring segments not been ruptured. Stresses in the Unalaska Gap and the Shumagin gap are at a relatively high level and these segments of the plate boundary may be expected to rupture in the near future. In general, in the ten years (about 16% of the earthquake cycle for the Aleutians) following an earthquake, the stress recovery in the rupture zone is highly nonlinear, resulting in a much more rapid stress accumulation than the linear case. Even at a later stage of an earthquake cycle, adjacent ruptures can cause an acceleration of loading rate in addition to the coseismic stress jump. A good example is the influence of the 1964 Alaska earthquake on the 1938 rupture zone. A general conclusion of this work is that long term earthquake prediction models must take into account the nonlinear stress accumulation behavior in seismic gaps. Also, we have shown the interaction of adjacent plate boundary segments, which suggests that some large earthquakes may have been triggered by nearby ruptures.