Using Grey System Theory for Earthquake Forecast

By combining conventional grey correlation analysis, grey clustering method and grey forecasting methods with our multi-goal forecast thoughts and the techniques of grey time series processing, we develop six different grey earthquake forecast models in this paper. Using the record of major earthquakes in Japan from 1872 to 1995, we forecast future earthquakes in Japan. We develop an earthquake forecast model. By using the major earthquakes in Japan from 1872 to 1984, we forecast earthquakes from 1985 to 1995 and check the precision of the grey earthquake models. We find that the grey system theory can be applied to earthquake forecast. We introduce the above analysis methods and give a real example to evaluate and forecast. We also further discuss the problems of how to improve the precision of earthquake forecast and how to strengthen the forecast models in future research.

SeisGuard: A Software Platform to Establish Automatically an Earthquake Forecasting Model

SeisGuard, a system for analyzing earthquake precursory data, is a software platform to search for earthquake precursory information by processing geophysical data from different sources to establish automatically an earthquake forecasting model. The main function of this system is to analyze and process the deformation, fluid, electromagnetic and other geophysical field observing data from ground-based observation, as well as space-based observation. Combined station and earthquake distributions, geological structure and other information, this system can provide a basic software platform for earthquake forecasting research based on spatiotemporal fusion. The hierarchical station tree for data sifting and the interaction mode have been innovatively developed in this SeisGuard system to improve users’ working efficiency. The data storage framework designed according to the characteristics of different time series can unify the interfaces of different data sources, provide the support of data flow, simplify the management and usage of data, and provide foundation for analysis of big data. The final aim of this development is to establish an effective earthquake forecasting model combined all available information from ground-based observations to space-based observations.

Myths about Earthquakes:Quo vadis?

We are living in a world of numbers and calculations with enormous amount of pretty fast user-friendly software ready for an automatic output that may lead to a discovery or,alternatively,mislead to a deceptive conclusion,erroneous claims and predictions.As a matter of fact,nowadays,Science can disclose Natural Hazards,assess Risks,and deliver the state-of-the-art Knowledge of looming disaster in advance catastrophes along with useful Recommendations on the level of risks for decision making regarding engineering design,insurance,and emergency management.

The Collaboratory for the Study of Earthquake Predictability in China:Experiment Design and Preliminary Results of CSEP2.0

Since the inaugural international collaboration under the framework of the Collaboratory for the Study of Earthquake Predictability(CSEP)in 2007,numerous forecast models have been developed and operated for earthquake forecasting experiments across CSEP testing centers(Schorlemmer et al.,2018).Over more than a decade,efforts to compare forecasts with observed earthquakes using numerous statistical test methods and insights into earthquake predictability,which have become a highlight of the CSEP platform.

Critical analysis of the ULF power depression as a possible Tohoku earthquake precursor

Among electromagnetic methods of short-term earthquake prediction,an approach is being actively developed based on the phenomenon of magnetic ultra-low-frequency(ULF)power depression occurring a few days before an earthquake.In particular,a nighttime geomagnetic power depression in the band 0.03-0.05 Hz was observed approximately 5 days before the catastrophic Tohoku 2011 earthquake.To verify the reliability of this method,we performed an extended analysis using data from magnetometer arrays JMA,MAGDAS,PWING,and INTERMAGNET.The selected stations included sites close to the epicenter(<300 km)and remote points(~10000 km).The band-integrated spectral power of nighttime magnetic noise decreased significantly from March 6-9,several days before the earthquake.However,such variations occur simultaneously not only at nearby stations but also at distant stations.During this event,the ULF power depression was caused by low global geomagnetic activity,as evidenced by the planetary index SME.Thus,the depression of geomagnetic ULF noise cannot be considered a reliable short-term precursor.

The forecasting efficiency under different selected regions by Pattern Informatics Method and seismic potential estimation in the North-South Seismic Zone

In 2022,four earthquakes with M_(S)≥6.0 including the Menyuan M_(S)6.9 and Luding M_(S)6.8 earthquakes occurred in the North-South Seismic Zone(NSSZ),which demonstrated high and strong seismicity.Pattern Informatics(PI)method,as an effective long and medium term earthquake forecasting method,has been applied to the strong earthquake forecasting in Chinese mainland and results have shown the positive performance.The earthquake catalog with magnitude above M_(S)3.0 since 1970 provided by China Earthquake Networks Center was employed in this study and the Receiver Operating Characteristic(ROC)method was applied to test the forecasting efficiency of the PI method in each selected region related to the North-South Seismic Zone systematically.Based on this,we selected the area with the best ROC testing result and analyzed the evolution process of the PI hotspot map reflecting the small seismic activity pattern prior to the Menyuan M_(S)6.9 and Luding M_(S)6.8 earthquakes.A“forward”forecast for the area was carried out to assess seismic risk.The study shows the following.1)PI forecasting has higher forecasting efficiency in the selected study region where the difference of seismicity in any place of the region is smaller.2)In areas with smaller differences of seismicity,the activity pattern of small earthquakes prior to the Menyuan M_(S)6.9 and Luding M_(S)6.8 earthquakes can be obtained by analyzing the spatio-temporal evolution process of the PI hotspot map.3)The hotspot evolution in and around the southern Tazang fault in the study area is similar to that prior to the strong earthquakes,which suggests the possible seismic hazard in the future.This study could provide some ideas to the seismic hazard assessment in other regions with high seismicity,such as Japan,Californi,Turkey,and Indonesia.

Short-term and imminent geomagnetic anomalies of the Wenchuan M_S8.0 earthquake and exploration on earthquake forecast

The diurnal variation of the geomagnetic vertical component is exhibited mainly by changes of phase and amplitude before strong earthquakes. Based on data recorded by the network of geomagnetic observatories in China for many years, the anomalous features of the appearance time of the minima of diurnal variations （i.e, low-point time） of the geo- magnetic vertical components and the variation of their spatial distribution （i.e, phenomena of low-point displacement） have been studied before the Wenchuan Ms8.0 earthquake. The strong aftershocks after two months＇ quiescence of M6 aftershocks of the Ms8.0 event were forecasted based on these studies. There are good correlativities between these geomagnetic anoma- lies and occurrences of earthquakes. It has been found that most earthquakes occur near the boundary line of sudden changes of the low-point time and generally within four days before or after the 27th or 41st day counting from the day of the appearance of the anomaly. In addition, the imminent anomalies in diurnal-variation amplitudes near the epicentral areas have also been studied before the Wenchuan earthquake.

Research status of earthquake forecasting in hydraulicfracturing induced earthquakes

In the new types of industrial activities including unconventional energy extraction associated with shale gas and hot dry rock,gas reservoir operations,CO2 geological storage,undergoing research on induced earthquake forecasting has become one of the forward positions of current seismology.As for the intense actual demand,the immature research on induced earthquake forecasting has already been applied in pre-assessment of site safety and seismic hazard and risk management.This work will review systematically recent advances in earthquake forecasting induced by hydraulic fracturing during industrial production from four aspects:earthquake occurrence probability,maximum expected magnitude forecasting,seismic risk analysis for engineering and social applications and key scientific problems.In terms of earthquake occurrence probability,we introduce statistical forecasting models such as an improved ETAS and non-stationary ETAS and physical forecasting models such as Seismogenic Index(SI)and hydro-mechanism nucleation.Research on maximum expected magnitude forecasting has experienced four stages of linear relationship with net injection volume of fluid,power exponential relationship and physical forecasting regarding fault parameters.For seismic risk analysis,we focus on probabilistic seismic hazard assessment and quantitative geological susceptibility model.Furthermore,this review is extended to key scientific problems that contain obtaining accurate fault scale and environmental stress state of reservoir,critical physical process of runaway rupture,complex mechanism of fault activation as well as physical mechanism and modeling of trailing effect.This work in understanding induced earthquake forecasting may contribute to unconventional energy development and production,seismic hazard mitigation,emergency management and scientific research as a reference.

Application test of matter element analysis in earthquake forecast

Calculation by means of the previous indices of the seismic activity can have the matter element analysis possess the forecast function. Readjusting repeatedly the grade limit value of every index can maximize the historical fitting ratio of the calculated and actual grade of the annual maximum magnitude, whose result is relatively ideal.

Spatial and temporal synthesized probability gain for middle and long-term earthquake forecast and its preliminary application

The principle of middle and long-term earthquake forecast model of spatial and temporal synthesized probability gain and the evaluation of forecast efficiency (R-values) of various forecast methods are introduced in this paper. The R-value method, developed by Xu (1989), is further developed here, and can be applied to more complicated cases. Probability gains in spatial and/or temporal domains and the R-values for different forecast methods are estimated in North China. The synthesized probability gain is then estimated as an example.

A Preliminary Study on the Use of NCEP Temperature Images and Additive Tectonic Stress from Astro-Tidal-Triggering to Forecast Short-Impending Earthquakes

Taking the three earthquakes which occurred in Tibet, China during the period of July 12 to August 25, 2004 as an example,the paper analyses the M_S≥6.0 earthquakes that occurred in China and M_S≥7.0 earthquakes that occurred overseas since May of 2003 by combining the image data from the National Center for Environmental Prediction of America(NCEP)with the additive tectonic stress from astro-tidal-triggering (ATSA) and makes the following conclusions: The abnormal temperature image data of NCEP can better reflect the spatial-temporal evolution process of tectonic earthquake activity; The ATSA has an evident triggering effect on the activity of a fault when the terra stress is in critical status; using the NCEP images and the ATSA to forecast short-impending earthquake is a new concept; The three earthquakes occurred during the same phase of the respective ATSA cycle, i.e. that occurred at the time when the ATSA reached the relatively steady end of a peak, rather than at the time when the variation rate was maximal. In addition, the author discovered that the occurrence time of other earthquake cases during 2003～2004 in Tibet was also in the same phase of the above-mentioned cycles, and therefore, further study of this feature is needed with more earthquake cases in other areas over longer periods of time.

Problem and Improvement of R-values Applied to Assessment of Earthquake Forecast

The researches on the assessment of earthquake forecast are reviewed, then the R-value assessment is further developed theoretically in the paper. The results include the arithmetic of the R-values of earthquake occurrence under the condition that 'anomaly' occurred or no 'anomaly' occurred respectively, and the relation between the values. The distribution of Rvalue of a forecast method, corresponding to multi-status anomalies being independent each other, is also developed in the paper. The appropriate methods to estimate the R-values and extrapolate the occurrence probability of future earthquakes are also given in the paper.

Evaluation of numerical earthquake forecasting models

Evaluation of numerical earthquake forecasting models needs to consider two issues of equal importance:the application scenario of the simulation,and the complexity of the model.Criterion of the evaluation-based model selection faces some interesting problems in need of discussion.

On stress-forecasting strategy of earthquakes from stress buildup,stress shadow and stress transfer(SSS) based on numerical approach

Global Positioning System （GPS） and Interferometric Synthetic Aperture Radar （InSAR）, used for monitoring crust deformation, are found to be very promising in earthquake prediction subject to stress-forecasting. However, it is recognized that unless we can give reasonable explanations of these curious precursory phenomena that continue to be serendipitously observed from time to time, such high technology of GPS or InSAR is difficult to be efficiently used. Therefore, a proper model revealing the relation between earthquake evolution and stress variation, such as the phenomena of stress buildup, stress shadow and stress transfer （SSS）, is crucial to the GPS or InSAR based earthquake prediction. Here we address this question through a numerical approach of earthquake development using an intuitive physical model with a map-like configuration of discontinuous fault system. The simulation provides a physical basis for the principle of stress-forecasting of earthquakes based on SSS and for the application of GPS or InSAR in earthquake prediction. The observed SSS associated phenomena with images of stress distribution during the failure process can be continuously simulated. It is shown that the SSS are better indicators of earthquake precursors than that of seismic foreshocks, suggesting a predictability of earthquakes based on stress-forecasting strategy.

Loss forecasting of earthquake fire based on radial basis function network

According to complexity and multiplicity of the post-earthquake fire, the loss forecasting model of earthquake fire is established by using radial basis function neural network with adaptability, self-learning and fault-tolerant based on the historical information. The applicability and validity of the model is manifested through testing and discussion. A simple and available method is provided for the prediction of losses of other natural disaster.

A Review on the Research Progress in Operational Earthquake Forecasting(OEF)in the World

In this paper,the research progress of the Operational Earthquake Forecasting( OEF) is introduced from the major areas of concern,the concept of probability gain,hybrid model development,and the application to earthquake disaster reduction. Due to the development of OEF based on the global "Collaboratory for the Study of Earthquake Predictability( CSEP) " plan,it provides a significant technical foundation for earthquake forecast modeling and a practical foundation for solving the actual problems in earthquake preparedness and disaster mitigation. Therefore, related research and technical ideas provide inspirational and referential significance for earthquake forecasting/prediction.

Probability forecast of earthquake magnitude in Chinese mainland before A．D． 2005

A probability forecast method of earthquake magnitude, based on the earthquake frequency magnitude relation and the model of Bernoulli′s random independent trial, is applied to the earthquake risk assessment of seismic zones in China's Mainland before A.D.2005 in the paper. The forecasting results indicate that the probabilities of earthquake occurrence with magnitude 5 in seismic zones before 2005 are estimated to be over 0.7 in common and 0.8 in most zones; and from 0.5 to 0.7 with M =6; the maximum probability of earthquake occurrence with magnitude 7 is estimated at 0.858, which is also expected in Shanxi seismic zone. In west China's Mainland, earthquakes with magnitude 6 are expected to occur in most seismic zones with high probability (over 0.9 in general) ; the relatively high probabilities of earthquake occurrence (more than 0.7) with magnitude 7 are expected in the seismic zones surrounding the Qinghai Tibet plateau and south Tianshan seismic zone. A discussion about the result confidence and the relationship between the estimated probability and the possible annual rate of earthquake occurrence is made in the last part of the paper.

Ms 6.5 Earthquake Occurred in Ludian County of Yunnan Province,China,Although Forecast Issued before the Earthquake,Life Casualties and Property Losses were Still Caused Significant

1 Geography Location At 16：30 on August 3rd, 2014, Ludian County, Zhaotong City, Yunnan Province （27.1°N, 103.3°E） was hit by Ms 6.5 earthquake, with the maximum intensity is 9 and epicenter depth is around 12 km （Figs. 1 and 2）.

Research on strong earthquake type division and forecast method for subsequent strong earthquakes

The relationships between energy, amplitude and frequency of eanhquake are correlative with the property of the seismic source. And the grade of the correlativity can be used as an index to distinguish the types of strong earth quakes. Primarily the strong earthquake can be divided into three types of main-after earthquakes, double-main earthquakes and swarm of strong earthquake. There are similarity and a certain repeatability at the quantificational indexes of hypocenter property between the same type of strong earthquakes, which supply basis for the forecast of subsequent strong shocks. The reference indexes of after strong shock forecast which are valuable for the applica tions of the method of type-divided forecast come from the analysis about more than fifty strong shock wide-band (BPZ wave) recording data of CDSN from 1988 to 1997.

Intelligent Seismic-Acoustic System for Identifying the Location of the Areas of an Expected Earthquake

A brief overview of the state-of-the-art in the field of earthquake study and forecasting is presented in this paper. We analyze the principles of the methods of determining the coordinates of earthquake focuses by means of ground seismic stations. We demonstrate that those methods cannot be used in the system for monitoring of the beginning of the earthquake preparation process (in the network of RNM ASP stations). As we know, the earthquake preparation process is accompanied by spreading noisy seismic-acoustic signals. Theoretically, the system for monitoring of the beginning of the earthquake preparation process is based on the technologies for seismic-acoustic signal processing-Robust Noise Monitoring (RNM). Noise characteristics determined by RNM technologies indicate the beginning of anomalous seismic processes (ASP) and, consequently, the possibility of ASP monitoring. Considering that the seismic-acoustic signal can be represented as the sum of the useful signal and noise, we present the technologies for determining noise characteristics. It is demonstrated in the paper that a change in the estimate of the cross-correlation function between the useful signal and the noise, noise variance and the value of noise correlation determine the beginning of ASP. One RNM ASP station determines the beginning of ASP within a radius of about 500 km. Determining the location of an expected earthquake requires a network of RNM ASP stations. We analyze the results of noise technology-based monitoring of anomalous seismic processes performed from July 2010 to June 2015 on nine seismic-acoustic stations built at the head of 10 m, 200 m, 300 m and 1400 - 5000 m deep wells. Based on the results of the experimental data obtained in the period covering over three years, an intelligent system has been built, which allows for identifying the location of the zone of an earthquake, using the combinations of time of change in the estimate of the correlation function between the useful signal and the noise of the seismic-acoustic information received from different stations 10 - 20 hours before the earthquake. In the long term, the system can be used by seismologists as a tool for determining the location of the zone of an expected earthquake.