The Formation of Oscillation Patterns Based on the Planetary Gravitational Field and Their Suitability for Earthquake Prediction

The fluctuating planetary gravitational field influences not only activities on the Sun but also on the Earth. A special correlation function describes the harmonics of these fluctuations. Groups of earthquakes form oscillation patterns that differ significantly from randomly chosen control groups. These patterns are suitable as an element of an AI for the probability of earthquakes.

A review of tidal triggering of global earthquakes

Earthquake prediction remains a challenging and difficult task for scientists all over the world.The tidal triggering of earthquakes is being proven by an increasing number of investigations,most of which have shown that earthquakes are positively correlated with tides,and thus,tides provide a potential tool for earthquake prediction,especially for imminent earthquakes.In this study,publications concerning the tidal triggering of earthquakes were compiled and analyzed with regard to global earthquakes,which were classified into three main types:tectonic,volcanic,and slow earthquakes.The results reveal a high correlation between tectonic earthquakes and tides(mainly for semidiurnal and diurnal tides;14-day tides) before and after the occurrence of significant earthquakes.For volcanic earthquakes,observations of volcanoes on the seafloor and land indicate that volcanic earthquakes in near-shore volcanic areas and mid-ocean ridges have a strong correlation with tidal forces,mostly those with semidiurnal and diurnal periods.For slow earthquakes,the periodicity of the tremor duration is highly correlated with semidiurnal and diurnal tides.In conclusion,the tidal triggering of these three types of earthquakes makes a positive contribution to earthquake preparation and understanding the triggering mechanism,and thus,the prediction of these types of earthquakes should be investigated.However,there are still several inadequacies on this topic that need to be resolved to gain a definitiveanswer regarding the tidal triggering of all earthquakes.The main inadequacies are discussed in this paper from our point of view.

The medium- and short-term prediction methods of strong earthquakes based on neural network

The field of neural network has found solid application in the past ten years and the field itself is still developing rapidly. Neural network is composed of many simple elements operating in parallel. A neural network can be trained to perform a particular mapping and this is the basis of its application to practical problems. In this paper, new methods for predicting the strong earthquakes are presented based on neural network. Neural network learns from existing earthquake sequences or earthquake precursors how to make medium and short term prediction of strong earthquakes. This paper describes two neural network prediction models. One is the model based on earthquake evolution sequences, which is applied to the modeling of the magnitude evolution sequences in the Mainland of China, the other is based on earthquake precursors, which is applied to the modeling of the occurrence time of strong earthquakes in North China. Test results show that the prediction methods based on neural networks are efficient, and convenient. They would find more application in the future.

Application of a time-magnitude prediction model for earthquakes

In this paper we discuss the physical meaning of the magnitude-time model parameters for earthquake prediction. The gestation process for strong earthquake in all eleven seismic zones in China can be described by the magnitude-time prediction model using the computations of the parameters of the model. The average model parameter values for China are： b = 0.383, c=0.154, d = 0.035, B = 0.844, C = -0.209, and D = 0.188. The robustness of the model parameters is estimated from the variation in the minimum magnitude of the transformed data, the spatial extent, and the temporal period. Analysis of the spatial and temporal suitability of the model indicates that the computation unit size should be at least 4°× 4°for seismic zones in North China, at least 3° × 3° in Southwest and Northwest China, and the time period should be as long as possible.

The dawn of successful prediction of major earthquakes

Since 1949, Chinese scientists have successfully predicted occurrence of many major earthquakes, such as the Haicheng MT. 3 event in 1975 and the Asian Game Village shock of 1990. In recent 20 years, however, some seis-mologists abroad have taken a disappointed and pessimistic view to earthquake prediction because of several failures. They suggest that the efforts should turn toward other fields, such as identification of building＇ s earthquake-proof capability, enhancement of house strength, and development of precise observational systems which will facilitate fast loca- ting of future major temblors and emergent relief on site. Such a pessimistic feeling has also influenced some Chinese researchers of the seismological community who attempted to give up efforts for earthquake prediction. Meanwhile other scientific workers are insisting in experiments and practices in this field and achieved some inspiring results. In this paper, we present several representative cases to illustrate that earthquakes are predictable under some conditions.

Short-term Earthquake Prediction in the Sichuan-Yunnan Region Using the Method of Modulated Earthquakes

By scanning modulated or un-modulated earthquakes spatio-temporally in the region of Sichuan-Yunnan,short-term non-stationary seismic precursory patterns were extracted with significant difference and the characteristic of non-stationary short-term seismic anomalies were analyzed as well as prediction efficiency of modulated small earthquakes before a strong earthquake. Besides,small earthquake modulation ratios near the region of the epicenter were calculated and sorted by time. The results indicated that there were significant effects using the modulated earthquake method to predict earthquakes greater than MS6. 0 in a short time. Before the MS8. 0 Wenchuan earthquake,there were obvious short-term precursory seismicity gap patterns of modulated small earthquakes.

The Two-dimensional Time Coordinate System and Time Prediction Research of M≥6.7 Strong Earthquakes in the Sichuan-Yunnan Region

Since the 20 thcentury,the time intervals of M ≥6.7 strong earthquakes in the SichuanYunnan region show obvious regularity.Using the years of the strong events,a twodimensional time coordinate system is generated,based on which,the time prediction model is constructed for strong earthquakes in the Sichuan-Yunnan region.Prediction analysis shows that there is risk of generating four earthquakes with M ≥ 6.7 in the Sichuan-Yunnan region in the future 16 years,and there are strong signals for M ≥6.7earthquakes for periods 2012-2021 and 2025-2029.The strong earthquakes may occur around 2014-2015,2019 and 2027.

Design and implementation of low-cost geomagnetic field monitoring equipment for high-density deployment

The observation of geomagnetic field variations is an important approach to studying earthquake precursors.Since 1987,the China Earthquake Administration has explored this seismomagnetic relationship.In particular,they studied local magnetic field anomalies over the Chinese mainland for earthquake prediction.Owing to the years of research on the seismomagnetic relationship,earthquake prediction experts have concluded that the compressive magnetic effect,tectonic magnetic effect,electric magnetic fluid effect,and other factors contribute to preearthquake magnetic anomalies.However,this involves a small magnitude of magnetic field changes.It is difficult to relate them to the abnormal changes of the extremely large magnetic field in regions with extreme earthquakes owing to the high cost of professional geomagnetic equipment,thereby limiting large-scale deployment.Moreover,it is difficult to obtain strong magnetic field changes before an earthquake.The Tianjin Earthquake Agency has developed low-cost geomagnetic field observation equipment through the Beijing–Tianjin–Hebei geomagnetic equipment test project.The new system was used to test the availability of equipment and determine the findings based on big data..

The ultra-low-frequency magnetic disturbances associated with earthquakes

The ultra-low-frequency （ULF） electromagnetic emission is recently recognized as one of the most promising candidates for short-term earthquake （EQ） prediction. This paper reviews previous convincing evidence on the presence of ULF emissions before three major EQs. Then, we present further statistical study on the ULF occurrence, our networks of ULF monitoring in different spatial scales in Japan and finally we present several signal processings to identify the seismogenic emissions by showing latest results for recent large EQs.

Earthquake prediction from China's mobile gravity data

The relation between plate tectonics and earthquake evolution is analyzed systematically on the basis of 1998-2010 absolute and relative gravity data from the Crustal Movement Observation Network of China. Most earthquakes originated in the plate boundary or within the fault zone. Tectonic deformation was most intense and exhibited discontinuity within the tectonically active fault zone because of the differential movement; the stress accumulation produced an abrupt gravity change, which was further enhanced by the earthquake. The gravity data from China's Mainland since 2000 obviously reflected five major earthquakes （Ms 〉 7）, all of which were better reflected than before 2000. Regional gravity anomalies and a gravity gradient change were observed in the area around the epicenter about 2 or 3 years before the earthquake occurred, suggesting that gravity change may be a seismic precursor. Furthermore, in this study, the medium-term predictions of the Ms7.3 Yutian, Ms8.0 Wenchuan, and Ms7.0 Lushan earthquakes are analytically pre- sented and evaluated, especially to estimate location of earthquake.

V_p/V_s Anisotropy and Implications for Crustal Composition Identification and Earthquake Prediction

The ratio of P- to S-wave velocities （Vp/Vs） is regarded as one of the most diagnostic properties of natural rocks. It has been used as a discriminant of composition for the continental crust and provides valuable constraints on its formation and evolution processes. Furthermore, the spatial and temporal changes in Vp/Vs before and after earthquakes are probably the most promising avenue to understanding the source mechanics and possibly predicting earthquakes. Here we calibrate the variations in Vp/Vs in dry, anisotropic crustal rocks and provide a set of basic information for the interpretation of future seismic data from the Wenchuan earthquake Fault zone Scientific Drilling （WFSD） project and other surveys. Vp/Vs is a constant （Ф0） for an isotropic rock. However, most of crustal rocks are anisotropic due to lattice-preferred orientations of anisotropic minerals （e.g., mica, amphibole, plagioclase and pyroxene） and cracks as well as thin compositional layering. The Vp/Vs ratio of an anisotropic rock measured along a selected pair of propagation-vibration directions is an apparent value （Фy） that is significantly different from the value for its isotropic counterpart （Ф0）. The usefulness of apparent Vp/Vs ratios as a diagnostic of crustal composition depends largely on rock seismic anisotropy. A 5% of P- and S-wave velocity anisotropy is sufficient to make it impossible to determine the crustal composition using the conventional criteria （Vp/Vs≤1.756 for felsic rocks, 1.756〈Vp/Vs≤1.809 for intermediate rocks, 1.809〈Vp/Vs≤1.944 for mafic rocks, and Vp/V2〉1.944 fluidfilled porous/fractured or partially molten rocks） if the information about the wave propagation-polarization directions with respect to the tectonic framework is unknown. However, the variations in Vp/Vs measured from borehole seismic experiments can be readily interpreted according to the orientations of the ray path and the polarization of the shear waves with respect to the present-day principal stress directions （i.e., the orientation of cracks） and the frozen fabric （i.e., foliation and lineation）.

Studies and experiments on earthquake prediction during 1999～2002

This paper briefly reviewed the research progresses of earthquake prediction and/or forecasting in China during 1999~2002, especially focused on mid-short term prediction methods with approaches of seismicity, crustal deformation, electromagnetism, ground water and the analysis by synthesis, and the application of the methods to the practice of earthquake prediction.

Application of the value of nonlinear parameters H and ΔH in strong earthquake prediction

In this paper, the relation that the curves of nonlinear parameter H and its difference Δ H bear with strong earthquakes in North China has been studied. First, the RSH algorithm has been applied to the North China region; the schemes of six quantitative prediction indexes have been studied in detail and then tested by tracing back predictions. The result shows that all the six prediction schemes are of certain prediction efficiency and have passed the test. Among the six schemes, A and E are of the best effect, with correlation coefficients R of 0.47 and 0.48 respectively. We recommend these two schemes for practical use in prediction in the future. Furthermore, the relation between the curve of Δ H (the difference of H) and strong earthquake has been studied. Based on the above results, the RSΔH algorithm that uses the Δ H value to predict strong earthquake has been put forward and applied to predict strong earthquakes in North China. The correlation coefficient R of tracing back prediction by this method is 0.45; this means that this method is also of better prediction efficiency. A combined application of these two algorithms has also been proposed. By the combined method, the time length spanned by false predictions can be shortened and thus the R value can be raised.

Statistical simulation analysis of the correlation between the annual estimated key regions with a certain seismic risk and the earthquakes in China

We have analyzed the correlation of the annual key regions with a certain seismic risk and the earthquakes in China from 1990-1997 by the statistical simulation analysis method. The statistical simulation analysis method is effective to deal with space-time heterogeneity of earthquakes and risk regions, the values of simulating random prediction probability have been got after 105 count, the objective results have been got by comparing average probability between the simulating prediction and the practical prediction. The results show: (1) average probability of the practical prediction for the annual seismic key risk regions in China from 1990-1997 is higher than that of the simulating prediction by 0.037 19 using the method of pure random simulating risk regions; (2) average probability of the practical prediction is higher than that of the simulation prediction by 0.021 83 using the method of simulating risk regions with the different probability based on the earthquake activity; (3) average probability of the practical prediction is much higher than that of the simulating prediction by 0.209 62 in West Xinjiang region using the method of dividing the Chinese Continent into the three regions: West Xinjiang region, Southwest region of China and the other region.

An scientific evaluation of annual earthquake prediction ability

The scientific idea of earthquake prediction in China is introduced in this paper. The various problems on evaluation of earthquake prediction ability are analyzed. The practical effect of prediction on annual seismic risk areas in 1990~2000 in China is discussed based on R-value evaluation method, and the ability of present earthquake prediction in China is reviewed.

The focus parameters and their correlation from small earthquakes before and after the 1995 Douhe earthquake

Based on seismic source spectrum solution by multi-station and multi-event coda method, applying Brune seismic source model, we have got the source factors and spectra of 48 small earthquakes occurred before and after the Douhe earthquake of October 6 in 1995. The seismic moments, corner frequencies and stress drops are estimated from the Spectra, and their corrclation and variation with time before and after the Douhe ear-thquake are discussed. The results indicate that the source factors show good stability, their peak frequencies and variation with frequencyappear quite similar. Some events with higher stress drops occurred about one year before the Douhe ertquake.Taking into the account that the Stress drop is calculated from seismic moment and frequency, as well as the correlation betwen them, we emphasis that the higher stress drop mentioned here just implies the higher corner frequency than the normal value.

Information characteristics of ground fluid precursors of strong continental earthquakes

It has become seismologist's common view to attach importance to the study of the characteristics about the relationship among the space distribution of precursory anomalous stations, active structure, deep rock character, and different kinds of earthquakes. In this paper, the information characteristics of ground fluid precursors are analyzed with a few examples of earthquakes. The result shows that information characteristics of ground fluid precursors mainly demonstrate, temporally stage and acceleration pattern, specially, swarm and concurrence feature. It is a key scientific problem, we propose, to give deep study on the stage and concurrence pattern for realizing the seismogenic process as well as making relatively correct prediction to the potential earthquake focus and the occurrence time.

Research on nonlinear R／S method and its application in earthquake prediction

ＲｅｓｅａｒｃｈｏｎｎｏｎｌｉｎｅａｒＲ／ＳｍｅｔｈｏｄａｎｄｉｔｓｐｐｌｉｃａｔｉｏｎｉｎｅａｒｔｈｑｕａｋｅｐｒｅｄｉｃｔｉｏｎＢｉ－ＱｕａｎＷＡＮＧ（王碧泉）；Ｈａｎ－ＭｉｎｇＨＵＡＮＧ（黄汉明）；Ｈｏｎｇ－ＳｈｕｎＦＡＮ（范洪顺）；Ｃｈｕｅｎ...

The application of neural networks to comprehensive prediction by seismology prediction method

BP neural networks is used to mid-term earthquake prediction in this paper. Some usual prediction parameters of seismology are used as the import units of neural networks. And the export units of neural networks is called as the character parameter W_0 describing enhancement of seismicity. We applied this method to space scanning of North China. The result shows that the mid-term anomalous zone of W_0-value usually appeared obviously around the future epicenter 1~3 years before earthquake. It is effective to mid-term prediction.

On numerical earthquake prediction

Can earthquakes be predicted？ How should people overcome the difficulties encountered in the study of earthquake prediction？ This issue can take inspiration from the experiences of weather forecast. Although weather forecasting took a period of about half a century to advance from empirical to numerical forecast, it has achieved significant success. A consensus has been reached among the Chinese seismological community that earth- quake prediction must also develop from empirical fore- casting to physical prediction. However, it is seldom mentioned that physical prediction is characterized by quantitatively numerical predictions based on physical laws. This article discusses five key components for numerical earthquake prediction and their current status. We conclude that numerical earthquake prediction should now be put on the planning agenda and its roadmap designed, seismic stations should be deployed and observations made according to the needs of numerical prediction, and theoretical research should be carried out.