Application of the Double-difference Relocation Method Combined with Waveform Cross-correlation on the Three Gorges Reservoir Seismicity

In this paper,we use the double difference location method based on waveform crosscorrelation algorithm for precise positioning of the Three Gorges Reservoir( TGR)earthquakes and analysis of seismic activity. First,we use the bi-spectrum cross-correlation method to analyze the seismic waveform data of TGR encrypted networks from March,2009 to December,2010,and evaluate the quality of waveform cross-correlation analysis.Combined with the waveform cross-correlation of data obtained, we use the double difference method to relocate the earthquake position. The results show that location precision using bi-spectrum verified waveform cross-correlation data is higher than that by using other types of data,and the mean 2 sig-error in EW,NS and UD are 3.2 m,3.9 m and 6.2 m,respectively. For the relocation of the Three Gorges Reservoir earthquakes,the results show that the micro-earthquakes along the Shenlongxi river in the Badong reservoir area obviously show the characteristics of three linear zones with nearly east-west direction,which is in accordance with the small faults and carbonate strata line of the neotectonic period,revealing the reservoir water main along the underground rivers or caves permeated and induced seismic activity. The stronger earthquakes may have resulted from small earthquakes through the active layers.

Relocation of the M_S≥2.0 Earthquakes in the Northern Tianshan Region, Xinjiang, Using the Double-Difference Earthquake Relocation Algorithm

We applied the double-difference earthquake rdocation algorithm to 1348 earthquakes with Ms ≥2.0 that occurred in the northern Tianshan region, Xinjiang, from April 1988 to June 2003, using a total of 28701 P- and S-wave arrival times recorded by 32 seismic stations in Xinjiang. Aiming to obtain most of these Ms ≥ 2.0 earthquakes relocations, and considering the requirements of the DD method and the condition of data, we added the travel time data of another 437 earthquakes with 1.5 ≤ Ms 〈 2.0. Finally, we obtained the relocation results for 1253 earthquakes with Ms ≥2.0, which account for 93 % of all the 1348 earthquakes with Ms ≥ 2.0 and includes all the Ms ≥ 3.0 earthquakes. The reason for not relocating the 95 earthquakes with 2.0 ≤ Ms 〈 3.0 is analyzed in the paper. After relocation, the RMS residual decreased from 0.83s to 0.14s, the average error is 0.993 km in E-W direction, 1.10 km in N- S direction, and 1.33 km in vertical direction. The hypocenter depths are more convergent than before and distributed from 5 km to 35 kin, with 94% being from 5km to 35 kin, 68.2% from 10 km to 25 kin. The average hypocenter depth is 19 kin.

Double-difference tomography of P- and S-wave velocity structure beneath the western part of Java, Indonesia

West Java in the western part of the Sunda Arc has a relatively high seismicity due to subduction activity and faults.In this study,double-difference tomography was used to obtain the 3D velocity tomograms of P and S waves beneath the western part of Java.To infer the geometry of the structure beneath the study area,precise earthquake hypo・center determination was first performed before tomographic imaging.For this,earthquake waveform data were extracted from the regional Meteorological,Climatological,Geophysical Agency(BMKG)network of Indonesia from South Sumatra to Central Java.The P and S arrival times for about 1,000 events in the period April 2009 to July 2016 were selected,the key features being events of magnitude>3,azimuthal gap<210°and number of phases>8.A nonlinear method using the oct-tree sampling algorithm from the NonLinLoc program was employed to determine the earthquake hypocenters.The hypocenter locations were then relocated using double-difference tomography(tomoDD).A significant reduction of travel-time(root mean square basis)and a better clustering of earthquakes were achieved which correlated well with the geological structure in West Java.Double-difference tomography was found to give a clear velocity structure,especially beneath the volcanic arc area,i.e.,under Mt Anak Krakatau,Mt Salak and the mountains complex in the southern part of West Java.Low velocity anomalies for the P and S waves as well as the vp/vs ratio below the volcanoes indicated possible partial melting of the upper mantle which ascended from the subducted slab beneath the volcanic arc.

The Subduction Structure Beneath the New Britain Island Arc and the Adjacent Region from Double-Difference Tomography

We applied double-difference tomography to relocate seismic events and determine the lithospheric velocity structure beneath the New Britain Island arc and the South Bismarck Sea Basin,based on the local P wave arrival time dataset collected by the International Seismological Centre.Results of the seismic relocation and velocity inversion show that the subduction of Solomon Sea Plate along the New Britain Trench is spatially different above 150 km,and the subduction angle of the slab on the west side is higher than that on the east side.The relocated earthquakes also show that there are double seismic zones at the depths of about 30–90km beneath the New Britain Island Arc.The velocity structure shows that the dehydration of the subducting slab caused the low-velocity anomalies in mantle wedge above the slab,which are associated with the magmatic activities around the New Guinea-New Britain Island arc.Moreover,it shows that there is another low-velocity anomaly zone beneath the Bismarck mid-oceanic ridge with spatial variation.Beneath the west of the Bismarck mid-oceanic ridge,the low-velocity anomaly is weakly connected to the subducted Solomon Sea slab.Conversely,the low-velocity anomaly beneath the Manus Sea Basin is highly intertwined to the subducting slab and its mantle wedge,indicating that the subduction of the Solomon Sea Plate might be a key deep dynamic factor that drives the spreading of the Manus Sea Basin and the separation of the Bismarck Plate.

Analysis on Double-difference Earthquake Location and the Seismicity Pattern of the Yangjiang Earthquake Sequences

The locations of about 400 earthquakes in Yangjiang, Guangdong Province are determined using the double, difference earthquake location algorithm （DDA）. The seismicity pattern becomes concentrated from discrete grids. The rupture characteristics of the Yangjiang earthquake sequence show a conjugated distribution in NW and NE directions. The major distribution trends NE and dips NE with an angle of 30^o and a length of 30km,and the minor distribution trends NW and dips SE with an angle of 30^o and a length of 20km. The focal depth is 5km - 15km. The distribution of the Enping earthquake sequence,which is not far from Yangjiang,is NW-trending. The relationship between hypocenter distribution and geological structure is discussed.

Relocation of Uppermost Mantle Earthquakes in the Atlas Mountains, Morocco

Upper mantle earthquakes are usually associated with plate boundary tectonics, but rarely occur beneath intracontinental orogenic belts. In the Moroccan Atlas Mountains, earthquakes determined at subcrustal depths are a controversial topic because they are few in number compared to subduction zones and are not related to plate boundary tectonics. A recent increase of broadband stations in Morocco has revealed numerous events below the Atlas belts, thought to occur from the upper mantle. Using additional available stations, these Atlas events were relocated and new epicenter resolutions were acquired following rigorous depth and RMS error criteria. 309 events were reprocessed and epicenter depths obtained were between 31 and 240 km during the last 23 years. Temporal variations of High Atlas events appear to be continually dipping while Anti Atlas events show no temporal variation trends. In addition, a recent strong event M6.8 occurred in September 2023 at the transition crust-uppermost mantle followed by several aftershocks which have been relocated at uppermost mantle depths. These events support delamination model under the High-Middle Atlas which could flow southward beneath the Anti Atlas lithosphere, and explain the large variation observed in lithosphere thickness between the High-Middle Atlas, and the Anti Atlas. Subcrustal events beneath the Atlas may be related to upper mantle earthquakes beneath the neighboring Canary Islands which have experienced recent swarms and eruptions. This possible correlation cannot be excluded since descending and ascending material is necessary for a regional geodynamic balance.

The 2023 Turkey earthquake doublet: Earthquake relocation, seismic tomography, and stress field inversion

On February 6,2023,two earthquakes with magnitudes of M_(W) 7.8 and M_(W) 7.5 struck southeastern Turkey,causing significant casualties and economic losses.These seismic events occurred along the East Anatolian Fault Zone,a convergent boundary between the Arabian Plate and the Anatolian Subplate.In this study,we analyze the M_(W) 7.8 and M_(W) 7.5 earthquakes by comparing their aftershock relocations,tomographic images,and stress field inversions.The earthquakes were localized in the upper crust and exhibited steep dip angles.Furthermore,the aftershocks occurred either close to the boundaries of low and high P-wave velocity anomaly zones or within the low P-wave velocity anomaly zones.The East Anatolia Fault,associated with the M_(W) 7.8 earthquake,and the SürgüFault,related to the M_(W) 7.5 earthquake,predominantly experienced shear stress.However,their western sections experienced a combination of strike-slip and tensile stresses in addition to shear stress.The ruptures of the M_(W) 7.8 and M_(W) 7.5 earthquakes appear to have bridged a seismic gap that had seen sparse seismicity over the past 200 years prior to the 2023 Turkey earthquake sequence.

From Poverty to Prosperity How relocation to Aktas Town is a living-standards leap for Xinjiang people

"3,000 yuan per month,"proclaimed Abdulaziz Mehmet,a Uygur worker at Dena Shoes Factory in Kargilik County of Xinjiang Uygur Autonomous Region.Why is it noteworthy?Bangkok's minimum wage in 2024 is US$327.65,while Jakarta is US$332.92.Mehmet is earning significantly more than what he would getin either of the national capitals.

利用区域地震资料监测朝鲜地下核试验的研究进展

根据朝鲜6次地下核试验在中国东北及邻近地区产生的宽频带区域地震资料,中国科学院地质与地球物理研究所地震学学科组发展了一套用于监测地下核试验的地震学方法,主要包括震级测量和当量估计、高精度震中定位以及爆炸与天然地震事件识别等.在全球范围内,存在多个用于震级-当量转换的经验公式,确定何种公式适合于朝鲜半岛地区至关重要.通过搜集一组用于地震测深的化学爆炸的当量和埋深,并以这些已知爆炸源作为量规事件,能够标定朝鲜地下核试验场的震级-当量关系,从而实现对朝鲜地下核爆进行当量估计.在精确定位方面,发展了利用多事件之间波形互相关方法精确测定它们之间的走时差从而完成高精度相对震中定位.通过进一步利用Pn和Pg等多震相数据还实现了对核爆深度的相对定位.在爆炸震源识别方面,利用统计处理方法分析研究了不同类型事件所产生地震波的特征,包括6次地下核试验、4次天然地震和3次化学爆炸,以及一些矿区塌陷等.结果发现P和S类型波的振幅比,例如Pn/Lg、Pg/Lg和Pn/Sn等,在2 Hz以上能够较好区分各类震源.其中爆炸震源产生的振幅比显著高于天然地震的值.特别是,通过计算谱振幅比的台网平均值能够显著提高识别的可靠性.利用中国东北和附近地区地震台网所提供的数据可以准确地将朝鲜地下核试验从周边天然地震事件中识别出来.该方法同时得到化学爆炸的P/S谱振幅比值介于核爆炸和天然地震的群组之间.

易地搬迁社区体育文化生态系统的建构逻辑

易地搬迁是党中央做出的重大战略部署,是从根本上解决生态脆弱地区、偏远山区和民族地区群众脱贫发展的重要举措。易地搬迁社区的体育文化生态系统建构,不仅是社区文化建设的重要组成部分,更是促进搬迁居民社会融入、提升生活质量的关键途径。从价值逻辑看,它是实现国家搬迁工程的稳定的时代呼求,是促进易地搬迁居民社会适应的现实诉求,是培育居民文化认同与塑造居民价值秩序的理论诉求。从内容逻辑看,它是由体育社会生态和体育自然生态组成。从方法逻辑看,就搬迁居民而言,强化其文化认同;就政府而言,政府支持和认可其制度;就社会而言,关注和监督其发展是其基本实现路径。

Relocation method of microseismic source in deep mines

A new method, named relocation, was proposed to reduce the impact of sensor errors systematically, especially whenavailable data of sensors are abundant. The procedure includes evaluating the reliability of every sensors datum, processing the initiallocation by the credible data, and selecting a set of equations with optimal noise tolerance according to the relative relationshipbetween the initial location and sensors location, then calculating the final location by k-mean voting. The results obtained in thisresearch include comparing traditional location method with the presented method in both simulation and field experiment. In thefield experiment, the location error of relocation method reduced 41.8% compared with traditional location method. The resultssuggested that relocation method can improve the fault-tolerant performance significantly.

Earthquake relocation and 3-dimensional crustal structure of P-wave velocity in cen-tral-western China

采用中国中西部地区(2l°～36°N，98°～112°E)193个地震台在1992～1999年间记录到的9988次地震的Pg和Sg震相走时的读数资料，用Roecker的SPHYPIT90程序，反演了该地区三维地壳P波速度结构，并用SPHREL3D90程序进行了地震的重新定位．反演结果揭示了中国中西部地区地震P波速度结构明显的横向不均匀性，这些不同深度上波速的横向变化多以该地区的活动断裂为分界线．可以看出活动断裂两侧存在明显的速度反差．通过重新定位，得到了6459次地震的震源参数，这些精确定位的地震震中明显沿该区活动断裂呈现条带状分布，其范围和尺度清晰地表示了这一地区地震活动与活动断裂的紧密关系．其中，82％重新精确定位的事件的震源深度在20km以内．这一结果与笔者用双差地震定位法得到的重新定位的震源深度分布相一致．

基于微观企业数据的高技术制造业迁移特征分析——以北京市为例

基于2008-2016年北京市规模以上企业数据,运用标准差椭圆、核密度估计、游程检验等方法分析北京市内部高技术制造业企业迁移特征。结果表明:1)从属性特征上看,迁移企业以混合所有制和外资企业为主,中等规模的企业比小微型或大型企业更倾向迁移,同时营收更高的企业更易发生迁移。2)受集聚区根植性和嵌入性影响,超过77.19%的企业倾向于在亦庄经济技术开发区、上地、中关村等主要集聚区内部及其周边的集聚区拓展区迁移。3)北京市高技术制造业企业迁移过程大致分为适应期、迁移期和稳定期3个阶段,小微型企业适应期和达到稳定期的时间都相对较短,其迁移主要受规模增长的影响,而中等规模企业无论是适应期还是寻找新区位的迁移期都需要相对较长的时间,影响迁移的因素也更加复杂多样。

Energy-saving Architectural Designs for Relocation Residential Districts in North Jiangsu Province of China

By investigating present relocation residential districts for peasants whose houses are removed for the unified planning of rural areas in north Jiangsu Province, as well as residents' feelings about the environment of residential district, main architectural structures and energy consumption conditions, the indoor thermal environment, use of main heating and cooling facilities, residents' satisfaction on the acoustical and luminous environment, major space-enclosing structures and calculation of energy-saving designs are analyzed, and suggestions are given for the architectural design of relocation residential districts in the study area. It is stressed that the relationship between energy conservation and architectural layout, orientation, lighting, ventilation, selection of enclosing-structure materials, facade, color and style should be properly handled in the planning, and the focus is to control building orientation and shape coefficient, on the basis of which energy-saving designs of windows, exterior walls and roofs can be done. Energy consumption of present residential buildings is calculated and analyzed to bring forth new ideas to the energy-saving designs for relocation residential districts in north Jiangsu Province, and establish an architectural energy-saving system suitable for climatic and natural conditions of north Jiangsu to instruct the energy-saving designs of relocation residential districts in the study area.

易地扶贫搬迁老年人认知功能情况及其影响因素研究

背景易地扶贫搬迁老年人认知功能与其他老年群体相比可能存在一定差异,聚焦易地扶贫搬迁老年人认知功能,明确其影响因素,对于改善易地扶贫搬迁老年人认知功能具有重要意义。目的探讨山西省易地扶贫搬迁老年人认知功能情况,并分析其影响因素,为制订针对性的干预方案提供科学依据。方法2023年6—8月,采用多阶段分层抽样对山西省4个市(太原、忻州、吕梁、临汾)8个县24个易地扶贫搬迁安置点进行入户调查,共回收问卷1882份。采用中文版简易精神状态筛查量表(CMMSE)对受访老年人认知功能状况进行评估,根据受教育程度,小学及以下组>22分为无认知障碍;初中/中专及以上组>26分为无认知障碍。采用分层多元线性回归模型和多因素Logistic回归分析模型从社会人口学特征、健康相关行为、健康状况和社会与环境4个维度分析探究易地扶贫搬迁老年人认知功能的影响因素。结果最终纳入1848名山西省易地扶贫搬迁老年人为研究对象,CMMSE得分为(24.40±5.84)分。分层多元线性回归模型最终结果显示,年龄(B=-2.355)、受教育水平(小学及以下:B=-2.189)、婚姻状况(B=-0.987)、躯体锻炼(B=-0.792)、BMI(超重:B=1.034)、日常活动能力得分(B=0.900)、抑郁状况得分(B=-0.089)、社会资本得分(B=0.125)是山西省易地扶贫搬迁老年人CMMSE得分的影响因素(P<0.05)。山西省易地扶贫搬迁老年人中患认知功能障碍428例,认知功能障碍检出率为23.2%。多因素Logistic回归分析结果显示,年龄(OR=1.894,95%CI=1.398~2.566)、个人月收入(≤500元:OR=0.598,95%CI=0.380~0.943)、婚姻状况(OR=1.507,95%CI=1.078~2.106)、躯体锻炼(OR=1.673,95%CI=1.276~2.193)、BMI(超重:OR=0.543,95%CI=0.368~0.804)、日常活动能力得分(OR=0.805,95%CI=0.823~0.895)、社会资本得分(OR=0.958,95%CI=0.934~0.983)是山西省易地扶贫搬迁老年人认知功能障碍的影响因素(P<0.05)。结论山西省易地扶贫搬迁老年人认知功能障碍检出率为23.2%,年龄、受教育水平、婚姻状况、躯体锻炼、日常活动能力、抑郁状况、BMI、社会资本是山西省易地扶贫搬迁老年人认知功能的重要影响因素,应采取有效措施加强对这些关键因素的管理,预防易地扶贫搬迁老年人认知功能衰退。

智能汽车自动挪车控制策略研究

针对停车场地内因临时停车导致已泊车辆被堵的问题,提出了一种智能汽车自动挪车控制策略。该控制策略使智能汽车在停车位已满的情况下,能够实现临时停车和自动挪车,从而避免阻碍已泊车辆的正常出行。该控制策略通过将传感器技术、数据处理和路径规划算法相结合,确保智能汽车在复杂停车环境中自主应对各种挪车需求,实现自动挪车。

一种新三维速度模型在四川台网中的应用分析

为分析USTClitho2.0新三维速度模型应用于四川台网地震预警、大震速报和地震编目工作的可行性,本研究以四川台网人工分析的震相数据为基础,从两个方面测试新模型定位结果的可靠性:①基于四川台网现有的川滇3D三维速度模型和新模型,统一采用单纯型定位法分别对省内31次M≥3.0地震事件进行重新定位,验证两种三维速度模型定位结果的一致性;②采用新模型对2022年9月5日四川泸定M_(S)6.8主震及其2次强余震进行重新定位,比较其重定位结果与双差定位结果之间的偏差,进一步验证新模型结果的可靠性。结果显示:新模型与川滇3D三维速度模型对同一地震震中位置、发震时刻和震级的测定具有较好的一致性,但前者在定位用时方面优于后者。考虑到新模型的时效性,建议将该模型应用于地震预警与大震速报中。

2021年5月21日云南漾濞M_(S)6.4地震序列中的共轭走滑断层研究

基于全国地震编目系统提供的地震编目报告和地震事件波形数据,采用双差定位法对2021年5月21日漾濞M_(S)6.4地震序列(2021年5月18日至10月31日,M_(L)0.0以上)进行重新定位,得到7138次地震事件的精确震源位置;同时,利用震源机制波形反演(CAP)方法,获得了序列中39次M S≥3.0地震的震源机制解结果。以此勾勒出更多的构造细节和清晰的共轭断层形迹,并结合地震序列分布区域的野外地质调查,对此次走滑型地震的破裂过程与模式进行分析。结果显示:(1)漾濞M_(S)6.4地震主震断层为一组宽度约5 km、长度约60 km、走向约130°,向西南陡倾的右旋走滑断裂;该断裂属简单剪切模式,主断层两侧发育与其相交呈斜列式排列的R剪切破裂、R′剪切破裂、伸展破裂等次级共轭断层,地震序列的分布明显受到简单剪切的约束,呈现出单斜对称特征(整个地震序列北端东侧与南端西侧呈现出扫帚状、马尾状分布,而南端东侧与北端西侧则存在明显的地震平静区),其中M_(S)≥5的强震均发生在共轭断层与主断层相交的区域。(2)整个地震序列均分布于维西—乔后断裂西侧中生代沉积地层之上,主震断层的延伸方向与维西—乔后断裂存在一定的夹角,断层性质则与左白达断裂差异较大。研究认为,此次漾濞M_(S)6.4地震的发震构造为一组位于维西—乔后断裂与左白达断裂之间相对独立且未出露地表的隐伏断裂。

连采机自主移机轨迹绝对坐标控制方法研究

针对连采机自主移机,目前尚无成熟控制策略,结合地质条件的变化,根据连采机掘进的特点,提出一种连采机自主移机轨迹绝对坐标控制方法,一定程度上解决连采机智能化过程的关键技术问题之一。

易地扶贫搬迁移民社会适应对心理健康的影响——基于湖北省J县的调查

“全民健康”是健康中国战略的根本目的,心理健康为实现乡村振兴和防止返贫提供了必要的人力资本基础。基于压力过程理论,采用2021年湖北省J县744份易地扶贫搬迁移民的微观调研数据,从生计发展适应、基本生活适应、人际交往适应、情感适应四个方面构建社会适应指标,重点分析移民社会适应对心理健康的影响,并实证检验搬迁前耕地面积的调节效应。研究表明,首先,易地扶贫搬迁移民心理健康风险是乡村全面振兴工作亟需干预的关键问题,生计发展适应是社会适应的突出短板;其次,社会适应对心理健康具有显著正向影响,该影响效应存在群体差异,在老年群体、非城镇安置群体以及无非农工作经历群体中,社会适应的心理健康改善效应有限;再者,耕地是农民生计发展和情感寄托的关键要素,对于“以农为生”和“以农为业”的农民而言,搬迁会对他们造成离地冲击,这种影响随着搬迁前耕地面积扩大而放大,搬迁带来的离地冲击越大,搬迁后的社会适应对心理健康的促进效应越明显。上述结果在使用工具变量缓解内生性问题之后仍然成立。基于此,提出在推进健康中国建设、落实乡村振兴与巩固易地扶贫搬迁成果的政策制定中,应从多维度增强移民社会适应,提高安置社区治理与服务水平,促进移民社会交往,增强移民社区认同;应加强社区心理健康宣传教育,提高移民心理健康素养,做好心理帮扶;面对离地产生的生计和情感冲击,应将保障移民有效就业与收入稳定作为搬迁帮扶的基础工作。