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。     

权重加卸载响应比及其震例检验

对加卸载响应比理论在地震预测中的应用进行分析,提出了对“正地震”和“负地震”震级根据加载库仑应力的半日潮振幅进行加权的研究思路,并应用于1999年台湾集集地震、2002年阿拉斯加Denali地震和2003年日本Hokkaido地震的震前加卸载响应比的计算。结果表明,相比较传统加卸载响应比,权重加卸载响应比更能突出震前的异常信息。     

阿克陶M_S6.7地震前LURR异常演化特征分析

加卸载响应比理论是描述震源区介质损伤程度的一种地震预测方法。基于加卸载响应比理论,对2016年11月25日阿克陶M_S6.7地震前加卸载响应比时空演化特征和异常区的孕震积分时程曲线进行分析。结果表明,本次地震前,研究区出现了多个加卸载响应比高值区域,异常区呈现为环状或片状,随着地震孕育过程,异常区往震源附近迁移,发震地点在异常区边缘和内部,地震发生在异常高值减弱过程中,异常峰值到发震时间为1个月,远小于理论发震时间,这表明了研究区构造活动剧烈,孕震周期短的特征。     

2017年8月9日精河6.6级地震前LURR异常时空演化特征

基于加卸载响应比理论,对2017年8月9日新疆精河6.6级地震前加卸载响应比时空演化特征和异常区的孕震积分时程曲线进行分析。结果表明,在精河6.6级地震前,研究区出现了明显的加卸载响应比高值异常区域,异常区呈现环状特征;而且,异常区域随时间逐渐向震源附近迁移,异常演化过程中异常区域内部和周围发生了6次5级以上地震,其中,2次6级地震发生在异常高值减弱过程中,异常峰值到发震的时间分别为11、22个月,大于以往研究的理论发震时间,这可能是受构造应力区域性特征影响的缘故。     

加卸载响应比与震前应力积累模式研究

加卸载响应比是一种中短期地震预测方法.按照该方法,通常在大地震发生之前加卸载响应比时间序列会出现明显的异常高值.早先的研究发现,震前临界区域的选择对加卸载响应比的计算有很大影响.我们发展了一种使用震前应力积累区域取代传统圆形区域计算加卸载响应比的算法,提高了加卸载响应比的地震预测能力,其震前库仑应力场分布采用地震断层位错模型将同震滑移量反向滑移的方法计算.美国南加州近20年来发生的4次M6.5地震以及2008年中国汶川MS8.0地震的研究事实表明,使用库仑应力算法得到的加卸载响应比时间序列,前兆变化相对于圆形区域算法更为明显,且对目标地震的位置、震级预测更为明确.库仑应力算法的这一独特性质,使我们可以针对不同地区的活动构造特征对未来地震发生的地点和大小提供信息和约束.     

新疆中强地震前加卸载响应比时空演化特征分析与检验

加卸载响应比是一种刻画震源区介质损伤程度的物理学参数,它通过随时间的变化来反映地震孕育的过程来进行地震预测。通过对1990—1999年新疆地区部分中强地震前加卸载响应比时空演化特征进行分析,并基于该理论得到孕震积分的概念应用于震例中。结果表明:中强震震前在震中附近可能存在多个高加卸载响应比值区,它们大致围成椭圆状或环状,地震通常发生在异常高值波动或减弱的过程中;异常峰值至发震时间比理论时间要短,这可能表明新疆地区构造活动剧烈,孕震周期较短。     

加卸载响应比理论若干问题的深入研究及其三维数值模拟

地震孕育过程的实质是震源区的损伤演化过程 ,这一演化过程是远离平衡态的不可逆过程。加卸载响应比理论从这一基本点出发 ,根据孕震区介质对加载和卸载的不同响应 ,提出了地震预测的新方法。本文对加卸载响应比方法理论和应用中的若干问题进行了较深入的研究 ,主要得到以下结论 :1 )从损伤力学的角度对加卸载响应比的力学机理进行理论阐述 ,通过加卸载响应比与损伤变量在宏观和细观上的密切联系 ,论证了加卸载响应比的物理实质是定量地刻划了非线性系统偏离稳态 (或逼近失稳 )的程度。而地震的孕育发生过程正是孕震系统的损伤演化直至失稳…     

中国大陆地区中强地震前加卸载响应比异常时间尺度的统计研究

加卸载响应比理论是近年来提出的地震预测方法。本文进行了加卸载响应比异常时间尺度的统计研究，其中包括中国大陆地区5．0～8．1级的部分中强地震共30个震例，并得出加卸载响应比异常的时间尺度与未来地震震级之间的拟合函数。结果表明，地震前加卸载响应比异常的时间尺度与未来地震的震级具有正变关系，即震级越高，地震前加卸载响应比异常的时间尺度越长。根据加卸载响应比异常的时间尺度与震级之间的关系可以估计未来地震的发震时间，同时，可以确定加卸载响应比时空扫描过程中时问长度的大小。     

三原井水位固体潮加卸载响应比的地震异常

讨论了三原井水位在泾阳4．8级地震前的变化特征，重点是泾阳地震前水位对固体潮响应的变化，即固体潮加卸载响应率与加卸载响应比的变化，对水位观测资料的计算分析表明，震前加卸载响应率及响应比有“平稳－升高－恢复”的特征，说明水位固体潮加卸载响应比方法有可能捕捉5级左右近震的前兆信息。     

加卸载响应比在伊朗地区地震活动性研究中的应用

本文应用加卸载响应比理论，分别对2005年2月22日伊朗东南部克尔曼省扎兰德Ms6．4地震和2006年3月31日伊朗西部洛雷斯坦省Ms6．1地震2个震例进行了时程曲线分析；并用加卸载响应比方法对伊朗地区进行了时空扫描。通过考察加卸载响应比异常区域的演化过程，对该地区未来的地震活动性进行了研究。     

Simulation of the Load-Unload Response Ratio and Critical Sensitivity in the Lattice Solid Model

— The Load-Unload Response Ratio (LURR) method is an intermediate-term earthquake prediction approach that has shown considerable promise. It involves calculating the ratio of a specified energy release measure during loading and unloading where loading and unloading periods are determined from the earth tide induced perturbations in the Coulomb Failure Stress on optimally oriented faults. In the lead-up to large earthquakes, high LURR values are frequently observed a few months or years prior to the event. These signals may have a similar origin to the observed accelerating seismic moment release (AMR) prior to many large earthquakes or may be due to critical sensitivity of the crust when a large earthquake is imminent. As a first step towards studying the underlying physical mechanism for the LURR observations, numerical studies are conducted using the particle based lattice solid model (LSM) to determine whether LURR observations can be reproduced. The model is initialized as a heterogeneous 2-D block made up of random-sized particles bonded by elastic-brittle links. The system is subjected to uniaxial compression from rigid driving plates on the upper and lower edges of the model. Experiments are conducted using both strain and stress control to load the plates. A sinusoidal stress perturbation is added to the gradual compressional loading to simulate loading and unloading cycles and LURR is calculated. The results reproduce signals similar to those observed in earthquake prediction practice with a high LURR value followed by a sudden drop prior to macroscopic failure of the sample. The results suggest that LURR provides a good predictor for catastrophic failure in elastic-brittle systems and motivate further research to study the underlying physical mechanisms and statistical properties of high LURR values. The results provide encouragement for earthquake prediction research and the use of advanced simulation models to probe the physics of earthquakes.     

美国西部地区加卸载响应比的时空演化及地震活动性分析

美国西部地区位于环太平洋地震带, 该地震带是地球上地震活动最为强烈的地带, 为了研究该地区的地震活动性, 对该地区进行了加卸载响应比的时空扫描, 考察了该地区加卸载响应比异常区域的时空演化; 并用2001—2006年的扫描结果与次年实际发生的5级以上地震进行对比, 发现绝大部分的强震都发生在前一年的预测区域内。 根据加卸载响应比的时空演化和该地区的最新扫描结果, 对未来地震活动性进行了分析。     

大桥水库4.6级地震前后的库水加卸载响应比变化特征

多年的实测数据表明,大桥水库的坝前水位年变化约40m,库水对库盆的静压变化大约为4×105Pa,比固体潮的作用大2个量级,水库的蓄水和放水是对库区影响最大的加卸载力源。根据加卸载响应比理论(LURR),用库区的地震频次和能量分别研究在大桥水库诱发M_S4.6地震前后加卸载响应比的变化。结果表明:在大桥水库及附近相对较大的范围和水体附近相对较小的范围内,当库水加载过程中发生小震群时,地震频次加卸载响应比Y_n和C_r值显示高值异常,表明研究区岩石处于临近破裂状态,其后发生4.6级水库诱发地震;蓄水前后地震频次库水加卸载响应比Y_n和C_r值的平均值有明显差异;在大桥水库诱发的4.6级地震前,库水加卸载作用导致的地震频次及能量的加卸载响应比在震前存在明显的高值异常,震后异常消失。大桥4.6级震例表明库水加卸载响应比可有效应用于水库诱发地震的监测预报     

The Random Distribution of the Loading and Unloading Response Ratio Under the Assumptions of Poisson Models

This paper discussed the random distribution of the loading and unloading response ratio(LURR) of different definitions(Y_1～Y_5)using the assumptions that the earthquakes occurfollowing the Poisson process and their magnitudes obey the Gutenberg-Richter law.Theresults show that Y_1～Y_5 are quite stable or concentrated when the expected number of eventsin the calculation time window is relatively large(>40);but when this occurrence ratebecomes very small,Y_2～Y_5 become quite variable or unstable.That is to say,a high value ofthe LURR can be produced not only from seismicity before a large earthquake,but also from arandom sequence of earthquakes that obeys a Poisson process when the expected number ofevents in the window is too small.To check the influence of randomness in the catalogue tothe LURR,the random distribution of the LURR under Poisson models has been calculated bysimulation.90%,95% and 99% confidence ranges of Y_1 and Y_3 are given in this paper,which is helpful to quantify the random influe     

Earthquake Trend Around Sumatra Indicated by a New Implementation of LURR Method

The current implementation of LURR (Load/Unload Response Ratio) theory has shown promise in intermediate to short-term earthquake forecasting through past practice, but has also met difficulties at the same time. In this paper a new implementation of LURR method is presented to address one of the problems. The major change in the new implementation is that LURR values will result from a calculated maximum faulting orientation (MFO) instead of any focal mechanism selected by users. After comparison with the world stress map, the calculated MFO has been found to be in good agreement with the observation from the regional tectonic stress regime. The MFO pattern in the Indonesia region has a special feature which may be related to the unique subduction complexity. The MFO pattern in the Sumatra region in general is different from that in the Java region after the 2004 M 9.0 Sumatra Andaman Islands earthquake. This phenomenon may be supported by the evidence of the recent observation that a section in the southern part of the Sumatran arc is locked. Furthermore, the MFO pattern before the 2004 main shock is different from that after the event. Retrospective examination of the Indonesia region by means of this implementation can produce significant LURR anomaly not only prior to the 2004 main shock but also before the 2006 M 7.7 South Java earthquake. Therefore future great earthquakes might favorably be forecasted if the LURR anomaly detected by MFO method could be considered a precursor.     

Multi-Methods Combined Analysis of Future Earthquake Potential

Prior to an earthquake, natural seismicity is correlated across multiple spatial and temporal scales. Many studies have indicated that an earthquake is hard to accurately predict by a single time-dependent precursory method. In this study, we attempt to combine four earthquake prediction methods, i.e. the Pattern Informatics (PI), Load/Unload Response Ratio (LURR), State Vector (SV), and Accelerating Moment Release (AMR) to estimate future earthquake potential. The PI technique is founded on the premise that the change in the seismicity rate is a proxy for the change in the underlying stress. We first use the PI method to quantify localized changes surrounding the epicenters of large earthquakes to objectively quantify the anomalous areas (hot spots) of the upcoming events. Next, we delineate the seismic hazard regions by integrating with regional active fault zones and small earthquake activities. Then, we further evaluate the earthquake potential in the seismic hazard regions using the LURR, SV and AMR methods. Retrospective tests of this new approach on the large earthquakes (M > 6.5) which have occurred in western China over the last 3 years show that the LURR and SV time series usually climb to an anomalously high peak months to years prior to occurrence of a large earthquake. And, the asymptote time, t _c, “predicted” by the AMR method correspond to the time of the actual events. The results may suggest that the multi-methods combined approach can be a useful tool to provide stronger constraints on forecasts of the time and location of future large events.     

Load-Unload Response Ratio and Accelerating Moment/Energy Release Critical Region Scaling and Earthquake Prediction

-- The main idea of the Load-Unload Response Ratio (LURR) is that when a system is stable, its response to loading corresponds to its response to unloading, whereas when the system is approaching an unstable state, the response to loading and unloading becomes quite different. High LURR values and observations of Accelerating Moment/Energy Release (AMR/AER) prior to large earthquakes have led different research groups to suggest intermediate-term earthquake prediction is possible and imply that the LURR and AMR/AER observations may have a similar physical origin. To study this possibility, we conducted a retrospective examination of several Australian and Chinese earthquakes with magnitudes ranging from 5.0 to 7.9, including Australia's deadly Newcastle earthquake and the devastating Tangshan earthquake. Both LURR values and best-fit power-law time-to-failure functions were computed using data within a range of distances from the epicenter. Like the best-fit power-law fits in AMR/AER, the LURR value was optimal using data within a certain epicentral distance implying a critical region for LURR. Furthermore, LURR critical region size scales with mainshock magnitude and is similar to the AMR/AER critical region size. These results suggest a common physical origin for both the AMR/AER and LURR observations. Further research may provide clues that yield an understanding of this mechanism and help lead to a solid foundation for intermediate-term earthquake prediction.