纬向带在大震预报中的意义

讨论了纬向带在8级大震预报中的意义。论证了这些纬向带具有地球深部的背景。在它们与一些弧形构造和V形构造交会的部位易于发生8级大震。

试用累积求和方法研究地震活动平静现象及大震概率预报

以表征区域地震活动强度背景的震级期望值作为单个地震事件的目标值 ,利用震级累积和C值随时间的变化分析地震活动相对平静现象 ,并给出其显著性检验 .文中还定量分析了平静异常与大震的关系 ,提出了利用核函数对大震发生时间进行概率外推的方法 .用上述方法对华北区的山西、张家口—渤海地震带的部分地区及新疆区域进行计算 ,显示该方法能够描述地震活动平静现象 ,并可合理地对未来大震发生时间进行概率外推估计 .

中国南北地震带甘川段大震活动规律的讨论

中国南北地震带的甘川段（ 由甘肃通渭至四川康定） 中的７ 级以上大震多发生于太阳活动谷年及其附近。另外，该段中大震多在３５ 年的周期处和其黄金分割处发生。这些规律可供今后预测甘川段７ 级以上大震时参考。

季风系统振荡与地震预报

发现了中国不同年份 8级大震发生日期之间的倍九天时间间隔 ,对于陕甘宁地区 7级以上大震的类似时间特征也被发现了。这种时间间隔可能是不同年份相同季节具有倍九天时间间隔的季风振荡触发大震形成的。

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 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.

Correlation Analysis of Gridding of Earthquakes in Datong and Its Surrounding Areas and Implication for Earthquake Prediction

On the basis of the earthquake （gL I〉3.0） catalog in North China from 1970 to 2009, the pattern of temporal and spatial distribution of medium-small earthquakes in Datong and its surrounding areas is studied by correlation analysis with a focus on its anomaly before moderate and strong earthquakes. With different spatial scales, temporal scales and time steps, the spatial distribution of earthquakes is converted to a sequence, then the correlation coefficients between the spatial distribution of medium-small earthquakes in a long-term and a longer time are calculated for the analysis of anomalies before moderate and strong earthquakes. In the study region center on the epicenter of the 1989 Datong- Yanggao earthquake （Ms5. 9） within a radius of less than 0.8~, with the time length of 3600 days, the longer time length of 3700 days, and the time step of 100 days, the correlation coefficient from 1980 to 2009 is steady between 0.94 and 1.00, but there were anomalies with values less than 0. 94 in the 2 years before the 1989 Datong-Yanggao earthquake （Ms 5.9）, the 1991 Datong earthquake （ Ms 5.8） and 1999 Hunyuan earthquake （Ms 5. 6 ）, which indicates the spatial distribution of a medium-small earthquake is very different from steady background seismicity. The implication for earthquake prediction from the anomaly of the correlation coefficient is also discussed with the three conclusions： （1） Before moderate and strong earthquakes in Datong and its surrounding areas, the obvious change of spatial distribution patterns of medium-small earthquake can be a kind of seismic precursor of the 2-year time scale for the prediction of an earthquake＇s time. （2） As the study region is restricted within a radius of less than 0. 8~, the result of correlation analysis is also good for the prediction of an earthquake＇s location. （3） The method of correlation analysis in this paper helps recognize the anomaly of spatial distribution of medium-small earthquake.

Learning and Progressing Through Scientific Practices—Commemorating the 90th Anniversary of the Haiyuan Earthquake and Working to Improve the Ability of Earthquake Prediction and Seismic Hazard Reduction

The great Haiyuan earthquake occurred at 20:06:09 on December 16,1920 in the south of Ningxia Hui Autonomous Region.The magnitude of this earthquake is 8.5,listed as one of the three greatest earthquakes to ever occur in Chinese continent.This devastating earthquake killed about 230,000 people according to previous reports.Recent studies show that total casualties may have reached 270,000.The study of this earthquake using modern scientific and technological methods is the first in the history of earthquake research in China.Significant breakthroughs took place in the middle of last century.The earthquake surface rupture,with 200km in length and prominent left-lateral strike-slip displacement,was discovered.The first monograph on the Haiyuan earthquake was published.In the 1980s,innovative large-scale geological mapping technology for active faults was developed during studies on the Haiyuan earthquake surface ruptures,with the publication of the first large-scale map of the Haiyuan active fault.Quantitative studies were carried out on the fine structure and geometry of the fault zone,Holocene slip rate,co-seismic displacement,paleoearthquake and recurrence intervals and future earthquake risk assessment.The innovative studies also included rupture propagation along the strike-slip fault,evolution of pull-apart basins,determination of total displacement of the strike-slip fault,transition equilibrium between strike-slip displacement along its major strand and crustal shortening at the end of the strike-slip fault,and the mechanism of deformation on Liupan Mountain.On the occasion of the 90th anniversary of the Haiyuan earthquake,careful retrospect of scientific progress achieved during the recent 20 years would be helpful in providing further direction in the study of active faults and earthquake hazard reduction.While taking this occasion to remember those lost by the Haiyuan earthquake,we aim to make greater contributions to earthquake prediction and seismic hazard reduction.

Application of Ambient Stress Parameters to Short-Term Prediction of the 2004, M_S5.0 Shuangbai, Yunnan Earthquake

Based on the data recorded by the regional digital seismic network of Yunnan and using new methods, the short-term variations of the ambient stress field of Yunnan and its adjacent areas are monitored in real time. With the in-depth analyses of the spatial-temporal evolution of the ambient stress field prior to the 2004, Shuangbai M_S5.0 earthquake, concrete procedures for predicting the three elements of the earthquake are presented.

Two types of changes in apparent resistivity in earthquake prediction

Two types of changes in apparent resistivity (AR) have been linked to earthquake occurrences. This paper studies the changes and their causes, in detail with the ultimate purpose of developing and assessing a method of earthquake (EQ) prediction. The AR changes of the first type (CFT) are considered to be precursors related to earthquakes (EQs); these appear mostly in the medium-term period before EQs and in the short-term period preceding EQs. The changes of the second type (CST) are characterized by a turning anomaly of a long-trend AR variation or the drastically descending/ascending anomaly superimposed on such a variation; these appear synchronously in large areas, such as the Chinese mainland, and northern and northwestern China, ect. Their spatio-temporal clusters correspond well to high seismicities in the areas and distant great EQs around the Chinese mainland. Based on the behaviors of the two types of changes, the AR changes observed prior to the Ms8.0 Wenchuan EQ of 2008 are studied. The results show that in the medium-term period before the EQ, noticeable anomalies appeared synchronously at four stations around the Songpan-Ganzi active block, but only weak upward changes were observed in the short-term period preceding the EQ, which caused the prediction of the imminent EQ to fail.