Seismotectonic Study on the West Part of the Interaction Zone Between Southern Tianshan and Northern Tarim

The interaction zone between southern Tianshan and northern Tarim is located at the northeast side of Pamir. It is a region with high seismicity. We constructed a seismotectonic model for the west part of this zone from geological profiles, deep crust seismic detection and earthquake focal mechanisms data. Based on the synthesized geological features, deep crust structure, and earthquake focal mechanisms, we think that the main regional tectonic feature is that the Tianshan tecto-lithostratigraphic unit overthrusts on the Tarim block. The Tianshan tectonic system includes the Maidan fault and thrust sheets in front of the fault; The Tarim tectonic system includes the underground northern Tarim margin fault, conjugate faults in basement and overthrust fault in shallow. The northern Tarim margin fault is a high angle fault deep in the Tarim crust, adjusting different trending deformation between Tianshan and Tarim. It is a major active fault that can generate large earthquakes. The other faults, such as the Tianshan overthrust system and the Tarim basement faults in this area may generate moderately strong earthquakes with different styles.     

The Crust-Mantle Structure in Zhangbei-Shangyi Earthquake Area

The seismic data obtained from the wide angle reflection and refraction profiles that pass through Zhangjiakou area of Hebei Province were interpreted. Some conclusions drawn from the result are as follows: (1) The nearly EW-trending Zhangbei-Chongli crustal fault zone and WNW-trending Zhangjiakou-Bohai Sea deep crustal fault zone meet in the Zhangbei earthquake (Ms = 6.2) area; (2) At the intersection, the two deep crustal fault zones that stretch to the Moho and the discontinuities of interfaces within the crust form the path for large area basalt eruption in Hannuoba; (3) In the earthquake area, the local velocity reversal in the middle-upper crust and abnormal low velocity zone in the lower crust imply that the magmatic activity there is still fairly violent; and (4) The recent activity of Zhangjiakou-Bohai Sea deep crustal fault zone may be the main cause of the Zhangbei earthquake.     

大同—阳高震区深部构造背景

利用通过本区的宽角反射／折射剖面资料对大同－阳高震区及邻区地壳上地幔速度结构与构造进行了详细的研究,结果表明,地壳上地幔速度结构与构造在纵向和横向上具有明显的不均一性,浅部基底断裂发育,对应其深部,根据波组特征,壳内界面及速度等值线起伏变化和低速异常体的边界等推测了地壳深断裂带,区内最明显的上地壳低速体位于大同－阳原附近,其南界存在地壳断裂,大同－阳高地震群与该低速异常体和深断裂有关。     

The heterogeneous characteristics of crust-mantle structures and the seismic activities in the northwest Beijing region

Introduction Zhangjiakou-Bohai seismic zone is a major active seismic zone that passes through the north-ern part of North China. Zhangjiakou-Beijing area, the northwest part of North China, is located at the intersection position of Yanshan, Taihangshan uplift, and Shanxi down-faulted zone, and the geological structures in this area are extremely complicated. Many researchers in the geoscience circle always pay close attention to this region because Yanqing-Huailai region is located in th…     

南天山及塔里木北缘构造带西段地震构造研究

南天山及塔里木北缘构造带位于帕米尔地区东北侧,地震活动强烈。文中通过地质构造剖面、深部探测资料和地震震源机制解资料,综合研究了该区的地震构造模型。结果认为,该区的构造活动主要表现为天山地块逆冲于塔里木地块之上。天山构造系统包括迈丹断裂及其前缘推覆构造;塔里木构造系统包括深部的塔里木北缘断裂、基底共轭断层和浅部的推覆构造。塔里木北缘断裂是发育于塔里木地壳内部的高角度断裂,其形成原因在于塔里木和天山构造变形方向的差异。塔里木北缘断裂为研究区大地震的主要发震构造,天山推覆构造和塔里木基底断裂系统均具有不同性质的中强地震发震能力     

北京西北地区壳幔结构的非均匀性特征与地震活动

利用在北京西北部地区穿过张家口——渤海地震带北西段地震测深剖面进行了综合解释和研究, 揭示了延庆——怀来、 张北——尚义地震活动区异常的深浅地壳结构特征. 结果表明: 研究区基底结构具有明显的起伏变化, 不同的地质构造单元基底埋深存在着较大差异. 基底埋深在局部地段呈现出的急剧变化可视其为基底断裂存在的一种标志, 基底断裂与地壳深断裂的存在为岩浆的上溢提供了条件, 从而导致了地壳结构强烈的非均匀性. 延怀地区壳内复杂反射波组序列和局部强弱不连续反射带现象的出现, 表明该地区地壳结构发生了强烈的挤压变形, 从而构成了该地区复杂的地壳结构, 为该地区地震的发生提供了动力来源; 张北——尚义地区壳内不同深度范围低速异常体和局部的C1界面的存在, 可以认为是岩浆多期活动的产物, 在区域构造活动的作用下脆性的上地壳内, 当局部应力积聚到一定的程度从而引发了地震的发生.      

地震前地温突升现象研究

地温观测,特别是80 cm以下浅层和深井地温观测已基本上摆脱了外界等自然因素的干扰,是获取地热信息的一种比较直观、简便的度量.临震前出现的地温突升现象被认为是探测地震活动的有效手段,已越来越引起人们的普遍关注.文中对地震前浅层地温突升变化特征、浅层地温突升一些观测事实研究、深井地温突升的一些观测事实的研究以及地温突升现象的成因,分别进行了阐述.     

Characteristic of crustal structure in the Shulu fault basin and its vicinity

（王椿镛，张先康，林中洋，李学清）ＣｈａｒａｃｔｅｒｉｓｔｉｃｏｆｃｒｕｓｔａｌｓｔｒｕｃｔｕｒｅｉｎｔｈｅＳｈｕｌｕｆａｕｌｔｂａｓｉｎａｎｄｉｔｓｖｉｃｉｎｉｔｙ￥Ｃｈｕｎ－ＹｏｎｇＷＡＮＧＩ；Ｘｉａｎ－ＫａｎｇＺＨＡＮＧ；Ｚｈｏｎｇ－ＹａｎｇＬ...     

福建台网接入台湾台站对定位台湾中深源地震精度影响分析

福建台网负责监测中国台湾地区地震。对于中深源地震使用何种定位方法能获得较好的地震参数,这直接影响到地震定位精度。利用JOPENS系统中交互分析软件MSDP提供的定位方法,对同一地震进行两次定位,即不使用和使用接入的台湾台站,将福建台网得出的两次结果与中国台湾公布的地震参数进行对比,分析定位精度,进而找出适用于台湾地区中深源地震的定位方法,以便进一步判断在地震速报中使用这些台站进行辅助定位的可行性,并给出相关的操作方法及建议。     

强烈地震孕育与发生的地点、时间及强度预测的思考与探讨

进入21世纪以来,全球范围内强烈地震频频发生,势已进入到一个新的地震活动时期.我国大陆内部、周边和台湾岛内一系列强烈地震(M_S≥6.5)的发生,特别是2008年5月12日汶川M_S8.0大地震的突发与其震前的异常平静表明:地表与上地壳均未见有明显的或确切能构成短、临强烈地震预测的浅表层活动过程,大地震由深部壳、幔物质运动,即深层动力过程所致.基于对强烈地震孕育、发生和发展的初步研究提出:(1)面对强烈地震的预测必须强化震源深部介质和构造环境的研究与探索,以达对未来地震发生地点的预测.(2)在地震强烈活动地区长期坚守介质破裂效应及其派生物理响应的井中观测,即"抚模"震源区介质与结构的动态"脉搏",以达对地震发生时间的逐步逼近或预测.(3)深入剖析强烈地震活动区、带、点的深、浅层空间结构与动力过程,历史地震在地震活动地域的纵向和横向的分布特征及可靠前兆信息的同步性经验和统计效应与发展态势,以对未来强烈地震发生强度的估计.这三个方面均必须以地壳深部信息的采集和研究为前提,是地震学和地震预测深化研究与探索的必经之途！     

Analysis and study of the large earthquake risk in Yanqing-Huailai basin

ＡｎａｌｙｓｉｓａｎｄｓｔｕｄｙｏｆｔｈｅｌａｒｇｅｅａｒｔｈｑｕａｋｅｒｉｓｋｉｎＹａｎｑｉｎｇＨｕａｉｌａｉｂａｓｉｎＣＨＡＮＧＱＵＡＮＬＩＵ（刘昌铨）ＳＨＩＸＵＪＩＡ（嘉世旭）ＭＩＮＧＪＵＮＬＩＵ（刘明军）ＣＨＡＮＧＦＡＬＩ（李长发...     

用成都遥测台网记录判定深远震的几个问题

因成都遥测台网使用的记录器不同,通过对１９９６～１９９８年两年多的资料分析,发现采用常规的分析处理方法,有可能将深远震误作浅源震,其结果是震中位置偏差最大可达１５度。鉴于此情况,提出一种新的简易办法,可以改善深远震定位精度。     

吉林省汪清两次深源地震的研究

本文在给出了发生在吉林省汪清的两次深源地震的基本参数、CMT解及有感范围等基本情况的基础上，总结了对2002年6月29日汪清7．2级深源地震的预测情况。对汪清两次深震前出现的水位、水化学异常进行了分析，初步认为异常可能与深源地震孕育过程中引起的大区域应力场调整有关。对6月29日汪清7．2级深源地震前长春净月地震台体应变仪记录到的前驱波机理进行了分析，认为对前驱波机理的研究，可能成为地震预测的一个突破点。     

深厚软土场地基岩地震动反演——以天津波为例

根据天津波地表加速度记录和相应实测场地钻孔资料,采用等效线性化方法模拟土体非线性,进行了深厚软土场地基岩地震动反演,研究了频率截断对深厚软土场地基岩地震动反演的影响,为天津波地表加速度记录提供了相应的基岩地震动输入。研究表明:不同截断频率情况下,反演得到的基岩地震动峰值和反应谱曲线形状均相差悬殊,但反演后再正演所得到的地面运动与原地表记录相比,加速度时程曲线形状和峰值大小、反应谱曲线形状和峰值大小均非常接近;可根据工程需要对地表加速度记录进行不同频率的截断,反演得到所需强度的基岩地震动。     

Three-dimensional characteristics of focal fault of 1995 M S=6.5 Wuding earthquake occurring in Yunnan Province

By means of the hypocenter distribution and focal mechanism of Wuding MS=6.5 earthquake sequence occurred in 1995, the space orientation and activity characteristics of focal fault of Wuding earthquake have been studied from the three-dimensional space-time process. The results indicate that the focal fault of Wuding earthquake is a subsurface, NWW-trending, upright and right-lateral strike slip fault which is consistent with the intensity distribution in the meizoseismal region. Although the large-scale NS-trending Tanglang-Yimen active fault passes through the earthquake region, it is irrelevant to the MS=6.5 Wuding main earthquake. Since the relationship between the strong earthquake and the shallow geological active fault can not be determined, the crustal deep structure should be studied. The method proposed in the paper can be used to distinguish the focal fault in the deep crust.     

Comparison of the earthquake detection abilities of PhaseNet and EQTransformer with the Yangbi and Maduo earthquakes

PhaseNet and EQTransformer are two state-of-the-art earthquake detection methods that have been increasingly applied worldwide. To evaluate the generalization ability of the two models and provide insights for the development of new models, this study took the sequences of the Yunnan Yangbi M6.4 earthquake and Qinghai Maduo M7.4 earthquake as examples to compare the earthquake detection effects of the two abovementioned models as well as their abilities to process dense seismic sequences. It has been demonstrated from the corresponding research that due to the differences in seismic waveforms found in different geographical regions, the picking performance is reduced when the two models are applied directly to the detection of the Yangbi and Maduo earthquakes. PhaseNet has a higher recall than EQTransformer, but the recall of both models is reduced by 13%–56% when compared with the results reported in the original papers. The analysis results indicate that neural networks with deeper layers and complex structures may not necessarily enhance earthquake detection performance. In designing earthquake detection models, attention should be paid to not only the balance of depth, width, and architecture but also to the quality and quantity of the training datasets. In addition, noise datasets should be incorporated during training. According to the continuous waveforms detected 21 days before the Yangbi and Maduo earthquakes, the Yangbi earthquake exhibited foreshock, while the Maduo earthquake showed no foreshock activity, indicating that the two earthquakes’ nucleation processes were different.     

中国东北深源地震定位方法解析

黑龙江省有时会发生震源深度300-600 km的深源地震,且地震释放能量及有感范围均较大。该地区发生M > 6.0深源地震会产生较大社会影响,对于深源地震,快速准确地确定震源参数具有重要意义。利用黑龙江省测震台网自"十五"项目投入运行以来记录的31条深源地震数据,采用LocSAT和HypoSAT定位方法进行重新定位,将定位结果与中国地震台网中心统一编目给出的目录数据进行对比,寻求更加适用该区深震的定位方法。分析表明,对于黑龙江省测震台网记录的东北地区深源地震,使用HypoSAT方法进行定位结果优于LocSAT定位方法。     

不同类别场地地震动参数的计算分析

基于188个工程场地计算剖面及场地地震反应分析的等线性化波动分析方法，通过对场地地震反应的计算及计算结果的分析，研究了4类场地条件对场地地震动影响的特点及规律，给出了每一类场地地震动参数变化的经验关系。     

The shock event of October 6, 1597 is a strong deep earthquake

A special earth shock event was recorded at 22 counties of the 7 provinces of eastern China on October 6, 1597, and 2 volcanic eruptions and seismic activities were recorded in Sanshui county, Xianjingbeidao, Korea at that day and the 3rd day. Because of the large range of this shock, low intensity, slow attenuation and no extreme-earthquake area, its epicenter and focus could not be determined onthe scientific-technological conditions at that time. In the Seismological Catalogue of China (GU, 1983) published in 1983, its epicenter was determined to be in the Bo Sea (38.5°N, 120.0°E), its magnitude was 7; and it was changed into 7.5 in the later Seismological Catalogue of Beijing; someone estimated it over 7(HUAN, 1989); someone thought that, it was a very large earthquake, might be a extraordinarily serious large one according to the scale of sensational range, reaching 8 (SHI, et al, 1985). The authors think that, the disputes on its magnitude and epicenter, and on deep or shallow earthquake show the complicities of this problem; further discussions about it will be helpful to the study on the seismic activity of the northern China area.     

唐山地震深浅构造关系研究

地表观察和浅层高分辨率地震探测表明 ,唐山断裂与地震地表主破裂带的位置、产状均一致 ,且具有高角度西倾的逆冲走滑性质 ,发生过右旋水平错动和向东逆冲的垂直活动 ,而次破裂带与褶皱构造活动引起的其他断裂直接相关。根据瞬变磁场和深地震探测结果分析 ,唐山地区存在莫霍面斜坡和地壳“背斜”、中地壳水平滑脱和扩展断裂、上地壳高角度逆冲走滑断裂和背向斜构造 ,它们组成 1幅多层次、多级序的复式逆断裂 -扩展背斜构造图像 ,控制了唐山地震的孕育和发生