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| 1 | The 20 April 2013 Lushan, Sichuan, mainshock, and its aftershock sequence: tectonic implications显示文摘Using the double-difference relocation algorithm,we relocated the 20 April 2013 Lushan,Sichuan,earthquake(MS7.0),and its 4,567 aftershocks recorded during the period between 20 April and May 3,2013.Our results showed that most aftershocks are relocated between10 and 20 km depths,but some large aftershocks were relocated around 30 km depth and small events extended upward near the surface.Vertical cross sections illustrate a shovel-shaped fault plane with a variable dip angle from the southwest to northeast along the fault.Furthermore,the dip angle of the fault plane is smaller around the mainshock than that in the surrounding areas along the fault.These results suggest that it may be easy to generate the strong earthquake in the place having a small dip angle of the fault,which is somewhat similar to the genesis of the 2008Wenchuan earthquake.The Lushan mainshock is underlain by the seismically anomalous layers with low-VP,low-VS,and high-Poisson’s ratio anomalies,possibly suggesting that the fluid-filled fractured rock matrices might significantly reduce the effective normal stress on the fault plane to bring the brittle failure.The seismic gap between Lushan and Wenchuan aftershocks is suspected to be vulnerable to future seismic risks at greater depths,if any. | Jianshe Lei Guangwei Zhang Furen Xie | 2014 | Earthquake Science2014，27，1： | 22 |
| 2 | 基于强震动资料的破裂过程快速反演及其自动化的可行性显示文摘破裂过程快速反演是目前快速获取地震灾害特征的主要手段之一,是震后应急工作的重要内容.近十年来基于远震资料开展的手动快速反演工作取得了长足进步,但在响应时间方面存在固有的局限,阻碍了反演效率的持续提升.我们根据新近发展的IDS(Iterative Deconvolution and Stacking)自动反演方法,尝试反演近场强震动资料确定破裂过程,探讨破裂过程反演自动化的可行性.对近几年国内发生的强震——包括2013年芦山MW6.6地震、2016年青海门源MW5.9地震和2016年新疆阿克陶MW6.6地震——的应用结果表明,采用IDS方法反演强震数据可以得到稳定可靠的破裂模型,且反演计算时间都控制在几十秒内.此外,以2008年汶川MW7.9地震为例,测试了不同子断层尺度、截止频率和地壳速度结构模型对反演结果的影响,发现滑动分布主要特征不强烈依赖于反演参数和地壳模型,证实了自动反演的稳定性和很强的适应能力.这一研究表明,基于强震动资料的自动反演可能是破裂过程快速反演的主要发展方向.特别地,在未来强震动台网持续发展、强震动数据的质量和共享速度都得到进一步提高之后,这一工作可望纳入到地震参数的常规自动测定工作中,为震后应急和海域地震的海啸预警提供急需的震源模型. | 郑绪君 张勇 马强 汪荣江 | 2018 | 地球物理学报2018，61，10： | 14 |
| 3 | Resolving rupture processes of great earthquakes: Reviews and perspective from fast response to joint inversion显示文摘Resolving rupture processes of great earthquakes has fundamental importance to the study of earthquake physics,rupture dynamics, fault zone structure, and evolving processes. It also plays an essential role in earthquake hazard estimation,emergency response and seismic hazard mitigation. This paper reviews the major progress of the earthquake rupture process studies in the last decades, with an emphasize on the research directions of the department geophysics of Peking University including real-time response, back-projection techniques, geodetic data analysis, joint inversion and inversion in complex earth medium. We discussed the advantages and limitations of tradition methods;proposed a systematic and integrated approach from fast-response to detailed study. We also raised perspectives of using source models for ground motion prediction and the possibility of full-dynamic inversion. | Han YUE Yong ZHANG Zengxi GE Teng WANG Li ZHAO | 2020 | Science China Earth Sciences2020，63，4： | 11 |
| 4 | 近场位移数据约束的2013年芦山地震破裂模型及其构造意义显示文摘以往的研究显示了2013年芦山MS7.0级地震发震断层的隐伏逆冲断层基本特征,但是破裂深部细节差异较大.本文以近场密集的同震形变数据约束芦山地震破裂面几何形状及滑动分布,结果显示芦山地震破裂面具有铲状结构,上部16km为43°~50°高角度断层,深部16~25km为小于27°的低角度断层,破裂深度与重定位的余震分布深度一致.破裂分布模型清楚显示上下两个断层上各有一个滑动幅度大于0.5m的峰值破裂区,最大滑动量1.5m位于13km深处.重定位的余震分布基本都落在最大滑动量等值线外部库仑应力增加的区域.芦山地震破裂面几何形状和滑动分布特征与2008年汶川MS8.0级地震映秀—北川破裂相似,支持龙门山冲断带发育大规模的近水平滑脱层,是青藏高原东缘地壳缩短增厚、龙门山挤压隆升的重要证据。 | 谭凯 王琪 丁开华 李恒 邹蓉 聂兆生 王迪晋 杨少敏 乔学军 | 2015 | 地球物理学报2015，58，9： | 11 |
| 5 | Significant isostatic imbalance near the seismic gap between the M8.0 Wenchuan and M7.0 Lushan earthquakes显示文摘A gravity network with 302 observation points has been established in the western Sichuan Foreland Basin(SFB) to explore Bouguer gravity anomalies(BGAs). Our observational results reveal that the BGAs are negative as a whole, with a maximum value of-220 m Gal(10-5m s-2)at the northwest region of the study area. The real Moho depths beneath the SFB revealed by BGA data change smoothly from 39.5 km in the southeast to 43.7 km in the northwest of the monitoring region. However, the isostatic ones deduced from Airy isostatic model and topographical data vary approximately 39.5–42.0 km. The maximum differences of 2.7 km between the real and isostatic Moho depths are found near the seismic gap between the M8.0Wenchuan and M7.0 Lushan earthquakes, where the crust is in the greatest isostatic imbalance of the monitoring region. Analysis of the isostatic state indicates that the deep dynamic environment near the seismic gap between these two earthquakes indicates an M C 7.0 earthquake in the future. This study indicates that we can use isostasy as a potential approach to study the dynamic process of crustalmaterial movement and to analyze regional potential seismic risks. | Guangyu Fu Guoqing Zhang | 2014 | Chinese Science Bulletin2014，59，34： | 7 |
| 6 | 芦山震中区上地壳剖面二维波速结构模型反演显示文摘CT技术已经广泛应用到科学和工程领域,特别是在地球物理学和土木工程质量无损检测方面.本文用精密可控的地震波雷达在芦山震中区持续300 s向地壳主动发射低能量的线性调频弹性波,通过高灵敏度的地震仪器接收信号,实现对上地壳剖面波速结构进行无破坏性探测.用短时傅里叶变换分析记录到的线性调频信号的时间和频率特征,并用能量累积法提取信号的走时形成走时曲线图,识别震相后用射线追踪方法进行P波走时反演,得到了芦山地震震中区上地壳剖面二维波速结构.分析结果表明地震波雷达发出的信号符合控制要求,重复性高达99.7%;用能量累积法得到的地震波走时曲线易于识别震相.从芦山地震震中区上地壳剖面二维波速结构中可以看出,在芦山震中区附近有明显的波速差异,并且出现了向上凸起、向下急剧下降,再缓慢上升,呈'铲形'特征,存在低速层,分析出芦山地震是一次逆冲型地震,并且距震中区近的检测点波速比偏低,距震中区远的检测点波速比偏高.通过与其他方法研究结果对比,证明了用地震波雷达信号走时反演地壳波速结构是可行的. | 刘明辉 彭朝勇 周银兴 陈阳 李江 王洪体 | 2016 | 地球物理学进展2016，31，1： | 6 |
| 7 | Characteristics of subsurface density variations before the 4.20 Lushan M_s7.0 earthquake in the Longmenshan area: inversion results显示文摘The 4.20 Lushan MS7.0 earthquake occurred on the southwest segment of the Longmenshan fault on 20 April 2013. Some meaningful information on the preparation and occurrence of this earthquake was found based on the dynamic variation of gravity(DVG). To examine the great progress of the Lushan earthquake, we obtained the density variation(DENV) derived from the DVG using the compact gravity inversion method in this article. The inversion results reveal three main findings:(1) the DENV in the crust in the Jinshajiang fault area changed from positive in 2010–2011 to negative in 2011–2012.(2) The DENV in the Xianshuihe fault area decreased continuously from 2010 to 2012.(3) The DENV of the uppermost mantle of South China decreased in 2010–2011 and increased in 2011–2012. We propose that the flow/expansion of the middle-lower crust beneath the Bayan Har block and Moho subsidence on the southwest margin of the Chuan-Dian block may have been the major causes of the Lushan earthquake. | Songbai Xuan Chongyang Shen Hui Li Hongtao Hao | 2015 | Earthquake Science2015，28，1： | 5 |
| 8 | 2013年Ms 7.0级中国芦山地震断层曲面模型的构建及其滑动分布的大地测量反演显示文摘根据中国芦山地震的余震序列分布和地质构造情况,联合GPS同震位移和水准测量数据,采用格网搜索法和方差分量估计(variance covariance component,VCE)方法建立了芦山地震的断层曲面模型。以建立的断层曲面模型为基础进行滑动分布反演,反演结果表明此次地震以明显的逆冲滑动为主,存在左旋趋势,断层的滑动主要发生在4.56~18.25km深度范围内,最大滑动量为0.70m,在深度12.64km附近,释放的能量为8.77×10^(18) N/m(相当于Mw 6.57级)。对曲面模型进行棋盘检验,结果表明其能够较好地分辨出断层深度浅于13km的凹凸体,其面积最小为8km×8km。 | 许才军 周力璇 尹智 | 2017 | 武汉大学学报(信息科学版)2017，42，11： | 5 |
| 9 | 一种基于有限动态源的烈度估计方法显示文摘首先,基于地震烈度与震级和震中距或震源距的经验关系,考虑实际地震断层的有限性以及几何学和运动学特性,提出了一种基于有限动态源模型的烈度预估方法.然后,利用数值实验讨论了体现几何学和运动学特性的参数的作用以及断层的倾角和破裂速度的影响;最后,将这种方法应用于近年来发生的两次破坏性地震,讨论了这种方法的实用性与不足之处.在实时获取破裂过程图像成为可能的今天,用这种方法预估烈度对于震后救援十分重要. | 许力生 张旭 魏强 李春来 | 2016 | 地球物理学报2016，59，10： | 3 |
| 10 | 小震震源机制解反演芦山断层倾角显示文摘断层的几何形态控制着上盘地层的变形特征,断层运动模型的地球物理与大地测量反演依赖于断层几何参数的给定,而在几何参数中,断层倾角参数对反演结果的影响最为显著.为探索芦山地震与地表同震位移的关系,本文以分布在芦山地震断层周围的地震震源机制解为起算数据,运用地震矩张量理论反演得到芦山地震断层面倾角的平均值为42°.为了进一步精细化断层的几何结构,根据震源机制解分布的差异特征,沿断层走向与断层面宽度方向将其划分成为3×3断层模型.经计算发现断层南段、中段、北段的倾角均随深度增加而减小,在同一深度上,断层中段的倾角小于南段和北段的倾角,在8~12 km深度时,从南到北断层面的倾角分别为66.29°、51.10°、55.22°,在12~16 km深度时,从南到北断层面的倾角分别为44.67°、34.95°、43.40°,在16~20 km深度时,从南到北断层面的倾角分别为42.00°、29.93°、31.11°.分别采用单一平面模型(1×1)与分段分层模型(3×3)计算地表同震位移,发现两个模型的计算结果具有较好的一致性.相对单一平面模型(1×1)而言,分段分层模型(3×3)的计算结果与GPS观测值符合性更好,由此表明本文给出的细化后断层更接近断层的真实形态. | 段虎荣 陈胜雷 李闰 闫全超 | 2019 | 地球物理学进展2019，34，5： | 1 |
| 11 | Seismic sentinel? An analysis of captive giant panda behavior in response to the Lushan earthquake in China显示文摘It is widely believed that various animal species can sense and respond to the geophysical stimuli that precede earthquakes,especially electromagnetic fields,although supporting field evidence is mostly anecdotal.Here we report on the reactions of four female giant pandas under observation over the three days prior to the Lushan(30.1°N,103.0°E)magnitude 7.0 earthquake that occurred in Sichuan province,China,on April 20,2013.We observed no significant generalized behavioral anomalies indicative of them perceiving an impending earthquake.We also observed no startle behaviors in the 5 s prior to tremors commencing,indicating that these pandas either did not detect or did not respond to precursor P-waves.Our findings suggest that although giant pandas have evolved in,and continue to occupy exclusively,a seismically active range in central China,they do not appear to perceive pre-earthquake geophysical warning signs. | Yuan Jin Xiaozan Ma Bo Luo Guiquan Zhang Rongping Wei Desheng Li Hemin Zhang Chris Newman Christina Buesching Dingzhen Liu | 2021 | Earthquake Science2021，34，6： | 0 |
| 12 | Extrusion deformation process of ground surface during the Lushan earthquake in China显示文摘Based on finite element method, the extrusion deformation process of ground surface during the Lushan earthquake(April 20, 2013) is investigated in this work. In order to construct the finite element model of Lushan earthquake structure, the geophysical layer model of Lushan area, the frictional characteristic of slip-weaken along the fault surface, and the Coulomb failure criterion are considered. Through the computation and the comparison with achievement on the Lushan focal dynamics, our researches indicate that:(1) The most extrusion deformation of ground surface occurred in the initial phase of earthquake procession, i.e., between the fourth and sixth seconds after the earthquake occurred.(2)Between the first and sixth seconds after the earthquake, the extrusion deformation concentrates on the surface projection of earthquake fault.(3) Between the first and third seconds after the earthquake, the extrusion deformation of ground surface is very tiny. Meanwhile, the extrusion deformation reaches maximum at the sixth second after earthquake.(4) After 6 s of Lushan earthquake, the extrusion deformation spread out of earthquake structure projection.(5) During the earthquake, the maximum of extrusion deformation on ground surface is larger than the final deformation of the post-earthquake, in other words, the ground extrusion deformation will lastly reach a relatively small value after the Lushan earthquake occurred. | Yuzhu Bai | 2017 | Geodesy and Geodynamics2017，8，2： | 0 |
| 13 | 2013年MS7.0芦山地震的动力学破裂过程及其影响因素显示文摘2013年4月20日在四川芦山发生了M S7.0地震,震源运动学反演结果给出了此次地震的破裂过程和同震滑动分布.为了更好地理解造成芦山地震破裂过程的力学原因,本文综合野外地质调查、余震定位、深地震反射剖面等结果,构建芦山地震铲型断层模型,以震源运动学反演结果为约束,将震源参数与震源附近的构造应力场结合,建立断层面上滑动量和牵引力的时空分布关系,通过试错法给定震源动力学计算参数模拟芦山地震破裂传播的可能情况,进而分析讨论不同动力学计算参数对芦山地震破裂过程和同震滑动分布的影响.结果显示,初始应力是决定断层是否发生错动的关键;临界滑动弱化位移D c对破裂滑动速率有着很大的影响;成核区半径和初始应力主要影响破裂成核的快慢;局部不均匀破裂强度主要影响破裂行为和断层最终滑动量分布.利用边界积分方程法可以有效计算芦山地震铲型断层模型的动力学破裂过程,再现此次地震的主要特征.通过探究动力学参数对破裂过程影响,可解释运动学反演结果所揭示的破裂特征的力学原因,对于深入了解地震震源过程的物理本质和预测未来可能发生的地震的主要特征有着重要的参考意义. | 马聪慧 钱峰 张海明 | 2021 | 地球物理学报2021，64，1： | 0 |
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