This article has summarized the shortcomings and deficiencies in the construction and operation of the earthquake monitoring station network of China, analyzes the trend of modernization development of the monitoring station network, and proposes measures and suggestions for upgrading and replacing the earthquake monitoring network of China from the perspective of a new development philosophy. It has also detailed the design and implementation of the national disaster prevention project.

On December 18, 2023, an Ms 6.2 earthquake jolted Jishishan County in the Linxia Hui Autonomous Prefecture in Northwest China's Gansu Province, causing substantial casualties and building collapses. The earthquake occurred in the Qilian Block on the northeastern border of the Qinghai-Tibet Plateau, where faults are highly active and the geological structure is complex. In this study, we utilized methods such as relocation, focal mechanism solutions, and earthquake rupture processes to describe seismogenic faults. The results indicated that the majority of aftershocks occurred at a depth of 12 km. The centroid depth of the main shock and the depth of the maximum rupture point during the rupture process were also 12 km. Various geophysical methods exhibited a high degree of consistency in depth exploration. Aftershocks were distributed mainly to the west and north of the main shock and extended in the NNW direction, primarily through unilateral rupture. The main shockwas a reverse thrust event with a small dextral strike-slip component. In this study, more regional data, such as previous GPS observations, field geological observations, and the distributions of the primary stress states in the region, were also incorporated. We inferred that the main shock was triggered by the main fault at the northern margin of the Lajishan Fault and that the movement of the main fault also activated some secondary faults. The compressive forces on both sides of the Lajishan Fault Zone led to the uplift of mountain areas, accompanied by some landslides, leading to this catastrophic earthquake event. In this article, the activity relationships among the 2022 Ms 6.9 Menyuan earthquake, the 2019 Ms 5.7 Xiahe earthquake, and the Jishishan earthquake under the action of regional stress are also discussed. This study provides additional evidence and new ideas for exploring the seismogenic process of the Lajishan Fault Zone and has implications for future in-depth research on underground activity in this region.

北京时间2022年1月8日1时45分青海海北州门源县(37.77°N,101.26°E)发生6.9级地震,中国地震台网中心部署的测试预警系统于震后5.3s产出首报预警结果,震后13min中国地震台网中心发布正式速报结果,同时联合多家单位启动地震应急产品产出工作,共产出震源参数、历史地震、地震构造、震源机制、余震定位、推测烈度等9类16种数据产品.产品结果显示,本次地震发生在青藏高原东北缘,位于柴达木-祁连地块、阿拉善地块和鄂尔多斯地块交汇处,震中位于冷龙岭断裂西段和托莱山北缘断裂交接部位.震源机制解表明该地震为一次走滑型事件,余震精定位结果显示主震西侧余震展布呈近EW向,主震东侧呈NW-SE向,与震中区域断裂走向基本一致,烈度速报推测极震区烈度达到Ⅸ度,区域面积约175km2,Ⅷ度及以上区域总面积约1442km2,涉及四乡一镇.

利用2015年1月至2021年5月28日期间我国云南省漾濞县及周边地区固定台站和漾濞地震后布设的流动台站所记录到的近震资料,使用双差层析成像方法获得了该地震震区的高分辨率地壳三维速度结构和震源位置。重定位结果显示,漾濞M6.4地震序列主要沿NW-SE向展布,与维西—乔后—巍山断裂走向一致,地震主要集中在4—10 km的深度范围,呈约80°高倾角分布。结合定位结果与三维速度结构显示:漾濞M6.4地震序列的空间分布与速度结构变化具有相关性,主震位于P波、S波高低速异常交界处,这种介质物性变化的交界地带可能有利于中强地震的孕育和发生,余震主要分布在低P波速度、高S波速度和低波速比的脆性区域;沿漾濞地震序列的分布走向,主震两侧呈现完全不同的速度结构,其西北部具有明显的高P波速度、低S波速度特征,该地区高密度、强韧性的地层可能是阻挡漾濞地震的NW向破裂而呈单向破裂特征的原因。

Seismicity in the Yangbi area is relatively active (Figure 1). Since 1970, 145 earthquakes of magnitude greater than 3.0 have occurred within 50 km, including 108 Ms3.0−3.9 events, 27 Ms4.0−4.9 events, 9 Ms5.0−5.9 events, and the latest one reported here, which, at Ms6.0−6.9, is the strongest in this 51-year record. In the area within 100 km of Yangbi, 312 earthquakes above magnitude 3 have been recorded since 1970, including 249 Ms3.0−3.9 events, 45 Ms4.0−4.9 events, 16 Ms5.0−5.9 events, and two Ms6.0−6.9 events; the other Ms6.0 earthquake occurred in Yongsheng, Yunnan, on October 27, 2001.

In this work, we collected the seismic travel-time data from a local dense array in the Rongxian-Weiyuan area since 2019 and the seismic networks. Double-difference seismic tomography method was used to invert the high-resolution three-dimensional velocity structure and hypocentral locations. The results show that most of moderate and small earthquakes occurred in NS trending clusters, which are not associated with known faults. Their focal depths generally range 2 similar to 5 km. These events are associated with velocity anomalies, mostly occurred at the high V-s anomalies above depth 5 km, while in the high-to-low anomaly transition zones of V-P and V-s in the depth range of 7 similar to 10 km. Synthesis of the relocation and velocity profile permit to speculate that the thickness of sedimentary cap is about 4 similar to 6 km, and some moderate earthquakes took place in crystalline basement. In the deep subsurface, higher P wave velocity anomalies are present in the seismic area north of the Huangjuepo fault compared with the Rongxian seismic area. In a similar stress state, the seismic area north of the Huangjuepo fault with larger strength is more difficult to rupture, which may be the reason for later occurrence of earthquakes in this region.

2021年5月22日02时04分11.3秒（北京时间）青海果洛州玛多县发生M7.4地震。中国地震台网中心在震后立即启动余震监测和统计工作,于震后9min发布正式速报结果。同时,中国地震台网中心联合多家单位,共产出9类14种数据产品。产品结果显示,本次地震发生在巴颜喀拉块体,位于甘德南缘断裂带和玛多甘德地震带之间,推测极震区的烈度达到Ⅸ度;震源机制解显示该地震为一次走滑型事件,余震在震中两侧均有分布,总体呈NW-SE走向;震源破裂过程的结果表明本次地震持续时间约为45s,主要能量在震后30s释放,地震的破裂方式为双侧破裂,最大滑移量达4.5m,地壳浅层滑动位移量较大,推测可能存在地表破裂。

The New National Standard (NNS) of earthquake magnitude have been used in the determination of earthquake magnitude. To estimate the magnitude impact of the NNS on the moderate-strong shallow earthquakes in quick report, the differences between the magnitudes of broad band surface wave (MS (BB)) and the magnitudes of old rapid determination are systematically analyzed based on the rapid report catalogue of M≥5.0 earthquakes in China mainland from 2001 to 2017. In addition, we make a comparative analysis on the MS (BB), MS (NEIC), MW (CENC) and MW (GCMT). The results show that the NNS magnitudes are basically consistent with that of the NEIC for M≥6. The frequencies of earthquakes with M≥5 and M≥6 decrease to about 60％ and 80％ of the original data, but difference is little when M≥6.5. The moment magnitudes estimated by China mainland are consistent with the international results. Because the earthquake magnitude is released using the moment magnitude in world and there is systematical difference between the moment magnitude and surface wave magnitude. Thus, we should take the moment magnitude as the rapid determination result in China to consistent with the international results. It may further decrease the frequency of M6 and M7 earthquakes.

Focal mechanism solutions and accurate source depths of earthquakes are important for understanding seismicity and structure of seismic faults. This work collected the seismic wave data of earthquakes with magnitudes M >= 5. 0 and 5. 0>M >= 4. 0,which occurred from January 1, 2010 to December 31, 2017, recorded by the national seismic network and the regional seismic network in Sichuan province. The focal mechanisms of these events were inverted applying the synthetic seismograms method. The results show that the earthquakes on the Longmenshan fault zone are of thrust focal mechanism. On the Xianshuihe fault zone, focal mechanism solutions are dominated by strike-slip. And in the southwest of the Sichuan-Yunnan block, normal faulting dominates the focal mechanism solutions. As the excitation energy of surface waves is sensitive to source depth, the surface wave amplitude spectrum is applied to determine the focal depth and compared with the results from China Earthquake Networks Center (CENC) , the U. S. Geological Survey (USGS), and the International Seismological Centre (ISC). The sources of the moderate-major earthquakes in the Sichuan region are mainly distributed in the upper-middle crust above 20 km. In the Longmenshan region, seismic sources are concentrated in the depth range from 10 km to 20 km. On the Xianshuihe fault zone, focal depths are confined about 10 km. In the southwest of Sichuan-Yunnan block, near the Litang and Jinshajiang faults, the depths of seismic sources are generally 5 km to 10 km.

. Chen Xiaoꎬ Yu Pengꎬ Zhang LuoleiꎬLi Yangꎬ Wang Jialin. Regularized synchronous joint inversion of MT and seismic data[J]. Seismology and Geologyꎬ 2010ꎬ 32(3): 402-408 (in Chines with English abstract) . Deng Qidongꎬ Cheng Shaopingꎬ Ma JinꎬDu Peng. Seismic activities and earthquake potential in the Tibetan Plateau[J]. Chinese Journal of Geophysicsꎬ 2014ꎬ 57(5): 678-697. Deng Wanmingꎬ Zhong Dalai. Crust ̄mantle transition zone and its geological significance in the lithospheric tectonic evolution[J]. Chinese Science Bulletinꎬ 1997ꎬ 42(23): 2474-2482 (in Chinese). Ding Zhifengꎬ He Zhengqinꎬ Wu Jianpingꎬ Sun Weiguo. Research on the 3 ̄D seismic velocity structures in Qinghai ̄Xizang Plateau [ J]. Earthquake Research in Chinaꎬ 2001ꎬ 17(2): 202 209 ( in Chinese with

2019年6月17日22时55分(北京时间),四川宜宾市长宁县发生了M6.0地震.中国地震台网中心用时10min发布正式速报结果,并开展余震监测和统计.同时,中国地震台网中心联合各有关单位,对台网数据进行分析处理,产出10类19种数据产品.产品结果显示:四川长宁M6.0地震极震区烈度达Ⅶ度,为一次逆冲型为主的事件,余震呈NWW向展布.据主震和余震分布方向,由区域地震构造图可初步推测,发震断层为NW向隐伏断层.

We present a Pn wave velocity and anisotropy model of the central segment of the North-South Seismic Belt in China, where there are numerous stable basins and active faults, making this segment attractive for extensive studies. The model was obtained by a tomographic analysis of 49,973 Pn wave phase readings collected by the China Earthquake Networks Center and temporary stations in Yunnan and Sichuan. The tomographic velocity model shows that the average Pn wave velocity is 8.06 km/s; prominent high-velocity (high-V) anomalies are visible under the Sichuan Basin, the Zoige Basin and the Ordos block, which clearly outline their tectonic margins. A pronounced low-velocity (low-V) zone is observed from the Songpan-Ganzi block to the Chuan-Dian and Daliangshan blocks, suggesting the presence of hot material upwelling. The station delay data show a gradual variation from negative to positive values, possibly reflecting a crustal thickness variation from the southwest to the northeast of the study area. A correlation between the Pn wave anisotropy and the distribution of velocity anomalies is observed: anisotropy is relatively weaker in the high-V anomaly zones beneath stable basins, while it is stronger in the low-V anomaly zones and the high-to-low-V anomaly transition zones. The high-resolution velocity and anisotropy tomographic model that we obtained could also provide a better understanding of the study area seismicity, since the occurrence of strong earthquakes seems to be related to the presence and strength of lateral heterogeneities at the uppermost mantle level.

At 06:34（CST）on Nov.18,2017,an M6.9 earthquake occurred in the Mainling County,Nyingchi Region of Xizang Autonomous Region,China.The epicenter is located at 95.02°E,29.75°N and the focal depth is about 10 km（Figure 1）.The epicenter is about 100km from the Mainling County.The average elevation within 5 km is about 3100 m.This earthquake has caused widespread concern among members of government,research institutions,and public

We present new high-resolution Pn velocity and anisotropy models beneath Mongolia and the adjacent regions by inverting 169,406 Pn arrivals. The data are selected from 786 permanent stations and 106 portable seismographs recently deployed in Mongolia and China's Inner Mongolia. The availability of new data acquired has allowed us to explore the uppermost mantle structures in great detail in this region, and the 2 degrees x2 degrees model resolution is capable of distinguishing small-scale geological features. Pn average velocity is 8.18km/s, substantially faster than the global average. Distinct contrast in the velocity of the uppermost mantle is observed between the central part and two ends of the Baikal Rift, with the presence of higher velocities under the Central Baikal Rift, indicating strong variation of lithospheric thinning across the entire Baikal Rift. Low velocity beneath the Hangay Dome implies partial melting of mantle reflected by asthenospheric upwelling. Azimuthal anisotropy in the upper and lower mantle lid is measured by grouping the travel time data into two phases by epicenter distance. The obvious depth dependence of Pn anisotropy beneath the Hentey Mountains suggests different origins of fabrics. The lower anisotropy may origin from asthenospheric flow, while the shallower fabric may exhibit the preserved lattice preferred orientation anisotropy in the uppermost mantle. Meanwhile, depth-dependent anisotropic structures and significantly low velocity are found beneath Tien Shan, most possibly suggesting that the lithospheric mantle thinning is experienced by either delamination or local asthenospheric upwelling.

The M s7.0 Jiuzhaigou earthquake with the hypocenter depth of 20 km occurred at the NNW extension line of the Huya fault located next to the eastern boundary of the Bayan Har block. The focal mechanism solution of the mainshock based on the W-phase source inversion showed a sinistral slip and the moment magnitude was M w 6.5. Over 3000 aftershocks were recorded within six days, among which the largest was M 4.8 and three others were larger than M 4.0. The value of the aftershock frequency attenuation coefficient P was 1.03, and the b value of the magnitude-frequency relationship was 0.68. The aftershock activities were relatively inactive but the attenuation was normal. Relocation results of 603 aftershocks were obtained by using the double-difference earthquake location algorithm and the location errors of the EW, NS and the vertical directions were 0.81, 0.84 and 1.59 km respectively. The mainshock occurred in the center of the aftershock region and ruptured on both sides along the strike direction. The aftershocks were distributed linearly along a NNW direction, and the fault plane was nearly vertical with a length over 30 km and a width of about 15 km. Aftershocks were more concentrated in the southeast than in the northwest. The focal mechanism solutions of most aftershocks in the central and southeastern regions were consistent with the mainshock, while those in the northwest were thrust-types, which might be related to the Minjiang fault. Meanwhile, the regional stress was released more in the central and southeastern regions than in the northwest. The maximum intensity investigated in the damage zone was up to IX. The maximum intensity region was located in scenic areas, therefore few people were present when the earthquake occurred at night. The peak acceleration was highest in the NS records, followed by the EW and vertical records. The design spectra of intensity for Jiuzhaigou was VIII, which is higher than the acceleration response spectra obtained from the Jiuzhaibaihe station, the nearest station which had strong motion recordings. These aforementioned factors may have contributed to the minor casualties resulting from this earthquake. The aftershock regions of the Jiuzhaigou earthquake, the 1973 M s6.5 Songpan northeast earthquake, and the 1976 M s7.2 Songpan earthquake are connected along the Huya fault which may extend to the northwest in the deep earth. Considering the rupture displacement distribution of the mainshock, the focal mechanism of aftershocks, and the stress drop, strong aftershocks are unlikely to occur in the central and southeastern Jiuzhaigou aftershock regions; however, the development of seismicity in the northwest and the Minjiang River fault should be noted. Static Coulomb stress triggering of other 4 earthquakes larger than M 6.5 occurred near the Ganqingchuan border were calculated using the Coulomb 3.3 software. The results indicated that the Jiuzhaigou earthquake was triggered by the Wenchuan earthquake and related to the stress adjustment in the study area.

在美国,超过1.43亿人面临地震风险威胁.如果社会公众能够理解其面临的风险,并采取积极防御措施,地震影响就能显著减小.美国国家现代地震监测系统(ANSS)通过协作对地震与大地测量数据进行汇集与分析,及时发布地震发生及其影响的可靠信息,为地震研究及危险性与风险评估提供数据,这是建立地震韧性国家的重要基础.作为对ANSS的投资成果,现在对于发生在美国或世界上任何其他地区的任何显著地震事件都能够用一套产品来快速表征,在地震危机来临之际为人们提供态势感知.ANSS监测工作服务于科学研究和地震工程需求,这包括改进人们对建构筑物地震响应的理解.作为参与美国国家地震减灾计划(NEHRP)的四个联邦机构之一,美国地质调查局(USGS)为ANSS提供了管理与财政支持.2000年,美国国会颁布 《国家地震减灾计划》再授权法案[公法第106-503号(Public Law 106-503)]时,作为该计划的一项支撑设施,创立了ANSS.ANSS是美国联邦政府、州政府和学术界的合作.由于认识到地震灾害危险性与风险的地区差异性,所以ANSS管理结构强调区域执行与国家集成.其允许与其他联邦和州政府机构以及与关注地震监测的地球科学界和工程界协作.ANSS推动地方、区域和国家层面各机构间建立合作伙伴关系,共同致力于减轻地震灾害损失.这些合作关系对于ANSS在全国范围内的协调、在区域范围内的规划与执行,以及争取地方支持都是有必要的.许多承办学术机构、部分州政府机构、其他联邦机构、私人基金会和科学组织为ANSS的成长和(或)运行提供了支持.建设ANSS的需求最初在美国地质调查局(U.S.Geological Survey,1999)题为《美国地震监测评估——国家现代地震监测系统的需求》的出版物中率先提出.这些需求包括加强国内各监测台网间协调、开发新的地震信息产品,以及在全国范围内扩建监测基础设施.2000年以来,ANSS强化了基础设施建设与伙伴关系建立,并开发了新的地震信息产品与服务.虽然现有资助尚未达到ANSS的预期计划,但其1999年所设定的在野外及建筑物、桥梁和其他构筑物中安装7100个现代化地震观测站点的总体建设目标,截止2016年年底,已经完成了42％.ANSS产品的及时性与有效性提升了政府机构、应急响应人员、公众及工程界与科学界对ANSS能力的期望值.作为ANSS的投资成果,地震信息服务发生了革命性的变化.ANSS的品牌服务包括:向政府和应急管理人员提供即时地震通知,通过地震通知服务系统以电子邮件或文本形式提供快速通知、震源特征产品、提供实时地震信息的ANSS网站、一套实时态势感知产品(地震动图ShakeMap、地震动图发布系统ShakeCast、全球地震响应即时评估系统PAGER、"你有感么?"DYFI)、ANSS综合地震目录ComCat,以及由工程强地面运动数据中心(CESMD)为工程师提供的产品.在未来10年中,为了满足预期,ANSS必须在聚焦提升基础服务稳定性的同时确保获得不断创新的能力.ANSS具备在全国范围内进一步提升地震安全性并开展震后响应与处置的能力.本报告描述了一系列特定的发展机遇,并形成了ANSS未来10年的重点工作,包括使ANSS确保地震危机时有备无患,加强城市地区地震安全性,拓展降低地震风险的观测数据获取能力.把握机遇、实现目标,额外的资助也是十分有必要的.创立伊始,ANSS被视为创新与风险并存.如今已证明,尽管只得到了部分资助,ANSS却是成功的.我们的国家在快速发展,国家的结构体系日趋庞大和复杂,如果耽于成就,接受现状,我们将会面临更多的地震风险.ANSS要充分发挥其在减轻地震灾害损失方面的潜力,就必须不断前行——引发地震的构造力是无情的,它们将永不停息,我们减轻国家地震灾害的努力也将永不停息.

The records of 168 global seismographic stations from 2 to 3 o'clock (UTC) on April 1,1936 have been collected in order to locate the strong earthquake M63/4 occurred in northeast Lingshan of Guangxi.The station readings were grouped and associated based on the macro-epicenter of Lingshan mainshock (22.5°N,109.4°E) and the initial P wave residuals of the seismic stations.Finally records of thirteen stations were successfully associated to Lingshan mainshock,and phase arrivals of 7-8 stations contributed to the event relocation.The routine location method and model of China National Seismic Network Center and ISCloc have been used to relocate the Lingshan mainshock,and the relocation results show that the distance between the two relocated epicenters is about 47.6 km.By comparison,the routine location method and model of China National Seismic Network Center are more suitable for the data with the poor observational conditions of Lingshan mainshock.

A M3.4 seismic event occurred in the Punggye-ri nuclear test site in North Korea at 16:29 on September 23,2017.We analyzed the waveforms of this event recorded by China earthquake network.In conclusion,this event is complex including an explosion occurred with a successive earthquake.Although the beginning of the event is explosion,fault dislocation plays the main role in the event.