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1.
On May 22, 2021, the MS 7.4 earthquake occurred in Madoi County, Qinghai Province; it was another strong event that occurred within the Bayan Har block after the Dari MS 7.7 earthquake in 1947. An earthquake is bound to cast stress to the surrounding faults, thus affecting the regional seismic hazard. To understand these issues, a three-dimensional viscoelastic finite element model of the eastern Bayan Har block and its adjacent areas was constructed. Based on the co-seismic rupture model of the Madoi earthquake, we analyzed the co- and post-seismic Coulomb stress change caused by the Madoi earthquake on the surrounding major faults. The results show that the Madoi earthquake caused significant co-seismic stress increases in the Tuosuo Lake and Maqin-Maqu segments of the East Kunlun fault (>10 ?kPa), which exceeded the proposed threshold of stress triggering. By integrating the accumulation rate of the inter-seismic tectonic stress, we conclude that the Madoi earthquake caused future strong earthquakes in the Tuosuo Lake and Maqin-Maqu segments of the East Kunlun fault to advance by 55.6-623 and 24.7-123 ?a, respectively. Combined with the influence of the Madoi earthquake and the elapsed time of the last strong earthquake, these two segments have approached or even exceeded the recurrence interval of the fault prescribed by previous research. In the future, it is necessary to focus greater attention on the seismic hazard of the Maqin-Maqu and Tuosuo Lake segments. This study provides a mechanical reference to understand the seismic hazard of the East Kunlun fault in the future, particularly to determine the seismic potential region. 相似文献
2.
1932年12月25日,甘肃玉门市昌马镇附近发生MS7.6地震(震中：39.70°N,96.70°E),此次地震是继1920年海原MS8.5地震、1927年古浪MS8.0地震之后青藏高原东北缘祁连山—河西走廊地震带内的又一强震。这组大地震活动无论在时间序列上还是在空间序列上都极其罕见,引起了众多国内外学者的广泛关注,普遍认为是一次陆内地震活动沿相关断裂带由东向西迁移的典型样例。基于PSGRN/PSCMP程序,以前人地表地质调查相关结果为约束,利用弹性位错理论获取昌马地震断层破裂模型,以此为基础,基于黏弹性半空间分层模型模拟计算昌马地震产生的地表同震三维形变场。通过研究单次地震与地震叠加的库仑应力变化对后续地震的触发关系,分别对海原地震、古浪地震以及它们的叠加对昌马地震的触发作用进行研究。结果表明：海原地震、古浪地震以及它们的叠加均未超过可能触发地震的经验阈值,故认为昌马地震可能不受海原地震和古浪地震所造成的库仑应力变化的影响。此研究可为利用实际形变解释昌马地震的孕震过程研究提供理论依据。 相似文献
3.
2021年5月22日,青海省果洛藏族自治州玛多县发生M_S7.4地震。以青海省地震局玛多地震烈度调查为基础,着重分析6个重点地区的房屋震害及极震区桥梁道路的破坏情况。此次地震震级高、伤亡轻,仅造成震中附近个别土木结构、砖木结构房屋出现倒塌破坏,部分砖混及框架结构出现楼梯间及填充墙开裂的现象,多数房屋基本完好;调查中还发现野马滩一号、二号大桥以及昌马河大桥均出现不同程度的倒塌损毁,这也为烈度图的划分提供了数据支持;最后对此次地震产生的次生地质灾害进行统计分析,并对灾后重建和抗震设防提出意见及建议。 相似文献
4.
Based on the seismic phase reports of the Yangbi area from January 1 to June 25, 2021, and the waveform data of M ≥ 4 earthquakes, we obtained the relocation results and focal mechanism solutions of the MS6.4 Yangbi earthquake sequence using the HypoDD and CAP methods. Based on our results, our main conclusions are as follows: (1) the MS6.4 Yangbi earthquake sequence is a typical foreshock-mainshock-aftershock sequence. The foreshocks of the first two stages have the obvious fronts of migration and their migration rate increased gradually. There was no apparent front of migration during the third stage, and the occurrence of the mainshock was related to stress triggering from a M5.3 foreshock. We tentatively speculate that the rupture pattern of the Yangbi earthquake sequence conforms to the cascading-rupture model; and (2) the main fault of the MS6.4 Yangbi earthquake sequence is a NW-trending right-lateral strike-slip fault. As time progressed, a minor conjugate aftershock belt formed at the northwest end of this fault, and a dendritic branching structure emerged in the southern fault segment, showing a complex seismogenic fault structure. We suggested that the fault of the Yangbi earthquake sequence may be a young sub-fault of the Weixi-Weishan fault. 相似文献
5.
2022年1月8日,青海省海北藏族自治州门源县发生MS6.9地震,震中位于青藏高原东北缘地区祁连—海原断裂带的冷龙岭断裂和托勒山断裂构造转换区域(37.77°N,101.26°E)。震后野外现场考察结果表明,此次地震形成的同震地表破裂带总长度约为26 km,整体走向NWW向,破裂性质以左旋走滑局部逆冲为主。断层错动造成的破坏形式以雁列式组合的张裂隙、张剪裂隙、挤压鼓包、断层陡坎等为主。其中,道河至硫磺沟段地表破裂最为强烈,规模大且连续性好,造成的震害最为显著,地表破裂规模向东、西两端逐渐衰减。破裂带穿过区域内多条河流,造成显著的冰面破裂变形,并沿河岸形成一系列的边坡崩塌、滚石等地质灾害。综合破裂带及震害规模分析,宏观震中位于道河至硫磺沟地区。 相似文献
6.
主要研究2009年7月24日西藏尼玛西南MS5.6地震的基本参数、地震序列特征、震源参数、发震构造等;利用震中附近600km范围内台站测定参数研究地震的震源机制解,与哈佛大学给出的震源机制解较一致,且与通过现场考察的发震断层走向具有一致性。研究认为本次地震发生在冈底斯山—拉萨块体内部,断裂为NNW向,主要受张应力作用产生左旋走滑正断层活动。此外还分析了震前地震学条带异常特征,结束表明,震前1年出现NW向条带非常显著,研究结论为该地区今后地震预测提供科学依据。 相似文献
7.
Coseismic deformation of the 2021 MW7.4 Maduo earthquake from joint inversion of InSAR,GPS, and teleseismic data 
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下载免费PDF全文 Chaoya Liu Ling Bai Shunying Hong Yanfang Dong Yong Jiang Hongru Li Huili Zhan Zhiwen Chen 《地震科学（英文版）》2021,34(5):436-446
The MW7.4 Maduo earthquake occurred on 22 May 2021 at 02:04 CST with a large-expansion surface rupture. This earthquake was located in the Bayan Har block at the eastern Tibetan Plateau, where eight earthquakes of MS >7.0 have occurred in the past 25 years. Here, we combined interferometric synthetic aperture radar, GPS, and teleseismic data to study the coseismic slip distribution, fault geometry, and dynamic source rupture process of the Maduo earthquake. We found that the overall coseismic deformation field of the Maduo earthquake is distributed in the NWW-SEE direction along 285°. There was slight bending at the western end and two branches at the eastern end. The maximum slip is located near the eastern bending area on the northern branch of the fault system. The rupture nucleated on the Jiangcuo fault and propagated approximately 160 km along-strike in both the NWW and SEE directions. The characteristic source rupture process of the Maduo earthquake is similar to that of the 2010 MW6.8 Yushu earthquake, indicating that similar earthquakes with large-expansion surface ruptures and small shallow slip deficits can occur on both the internal fault and boundary fault of the Bayan Har block. 相似文献
8.
2014年9月12日至2014年10月31日,在浙江文成-泰顺交界的珊溪水库区域发生了最大震级M4.2地震。珊溪水库地区曾在2002、2006年分别发生过最大震级为ML3.9、ML4.6的地震序列,受这2次地震作用影响,震区房屋已经遭受了一定程度的破坏。2014年地震现场调查发现,震区震感明显,房屋受损现象较为普遍,震害具有叠加效应,出现了"小震致灾"的现象。另外,在震中附近的一些道路边坡上,地震还引发了规模较小的崩塌、滑坡等地质灾害。 相似文献
9.
An MS 6.4 earthquake occurred in Yangbi, Yunnan province, on May 21, 2021. According to related investigations, the macro-epicenter of the earthquake is 6 km northwest of Yangbi County, and the seismogenic structure is the NW-trending Weixi-Qiaohou fault. The earthquake area is located in the hinterland of the Hengduan Mountains in the northwest of Yunnan province, a region dominated by high and medium-high mountains, with deep canyons and tectonic basins in between. Various geomorphic features are derived from drastic topographic changes and huge geological differences in the earthquake area. There are a variety of buildings in the earthquake-affected zone, including civil and brick-wood structures ones with weak seismic performance, as well as brick-concrete and frame ones with better seismic performance. This paper summarizes and analyzes different characteristics of the earthquake in different geomorphic units through field investigations of different buildings and geological disasters in the affected area. The results show that under the same earthquake intensity, the damage to most buildings (located in slope areas or rooted in weak strata) is amplified by the earthquake. The earthquake has exerted an obvious propagation effect along the direction of the seismogenic structure. Moreover, local ground fissures will aggravate the damage to the buildings even without surface dislocation. Thus, we suggest that attention should be paid to the ground fissures caused by the slope effect. The fissure areas may also be the disaster spot of collapses and landslides in case of a high-magnitude earthquake. 相似文献
10.
通过对2022年1月8日青海门源6.9级地震的震源机制、发震构造、房屋和重大生命线工程震害、地震地表破裂带等震害调查资料的综合分析,系统介绍了此次地震震源机制、发震构造、地震烈度分布特点、房屋破坏特征及机理、生命线工程破坏特征及地表破裂带特征。研究结果表明：门源6.9级地震震中位置位于冷龙岭断裂带的西段,性质以左旋走滑为主,其与震源机制解得到的结果相一致,均为走滑型破裂类型;地震最大烈度Ⅸ度,烈度Ⅵ度(含)以上面积约23 417 km2,等震线长轴呈NWW走向,长轴200 km,短轴153 km;整体上房屋破坏较轻,甘肃境内主要属Ⅶ和Ⅵ度区影响范围,极少部分为Ⅷ度区影响范围;此次地震中滑坡灾害和生命线工程震害较少,主要在Ⅸ和Ⅷ度区造成部分路面裂缝,最为严重的则为兰新高铁浩门至军马场区间祁连山一号隧道群线路桥梁严重受损,隧道震害主要集中在断层影响范围内,其中隧道受破坏严重段约350m,占隧道全长的5.33%,受破坏较严重段分别位于严重段大里程侧402m和小里程侧646m范围内,占隧道全长的15.96%,其余段落震害总体轻微;地震造成地表破裂带约22 km,地震造成的... 相似文献
11.
2022年1月8日青海省海北州门源县发生MS6.9地震,震中距离2016年1月21日门源MS6.4地震震中约33km,两次门源地震均发生在冷龙岭断裂附近,但在震源机制、主发震断层破裂过程及地震序列余震活动等方面显著不同。针对两次门源地震序列的比较分析,对研究冷龙岭断裂及其附近区域强震序列和余震衰减特征等具有重要研究意义。通过对比分析2022年门源MS6.9地震和2016年门源MS6.4地震余震的时空演化特征,发现二者在震源过程和断层破裂尺度上存在明显差异,前者发震断层破裂充分,震后能量释放充分,余震丰富且震级偏高;而后者发震断层未破裂至地表,余震震级水平偏低。综合分析两次门源地震序列表现出来的差异性,认为其可能与地震发震断层的破裂过程密切相关,且同时受到区域构造环境的影响。 相似文献
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13.
S. A. Fedotov A. V. Solomatin S. D. Chernyshev 《Journal of Volcanology and Seismology》2008,2(6):375-394
Results are reported from the ongoing 2007–2008 work using the method of long-term earthquake prediction for the Kuril-Kamchatka arc based on the patterns of seismic gaps and the seismic cycle. This method was successful in predicting the M S = 8.2 Simushir I. (Middle Kuril Is.) earthquake occurring in the Simushir I. area on November 15, 2006. An M S = 8.1 earthquake occurred in the same area on January 13, 2007. We consider the evolution of the seismic process and determine the common rupture region of the two earthquakes. The sequence of M ≥ 6.0 aftershocks and forecasts for these are given. We provide a long-term forecast for the earthquake-generating zone of the Kuril-Kamchatka arc for the next five years, April 2008 to March 2013. Explanations are given for the method of calculation and prediction. The probable locations of future M ≥ 7.7 earthquakes are specified. For all segments of the earthquake-generating zone we predict the expected phases of the seismic cycle, the rate of low-magnitude seismicity (A10), the magnitudes of moderate-sized earthquakes to be expected, with probabilities of 0.8, 0.5, and 0.15, their maximum possible magnitudes, and the probabilities of occurrence of great (M ≥ 7.7) earthquakes. The results of these forecasts are used to enhance seismic safety. 相似文献
14.
Jean M. Johnson Yuichiro Tanioka Larry J. Ruff Kenji Satake Hiroo Kanamori Lynn R. Sykes 《Pure and Applied Geophysics》1994,142(1):3-28
The 9 March 1957 Aleutian earthquake has been estimated as the third largest earthquake this century and has the longest aftershock zone of any earthquake ever recorded—1200 km. However, due to a lack of high-quality seismic data, the actual source parameters for this earthquake have been poorly determined. We have examined all the available waveform data to determine the seismic moment, rupture area, and slip distribution. These data include body, surface and tsunami waves. Using body waves, we have estimated the duration of significant moment release as 4 min. From surface wave analysis, we have determined that significant moment release occurred only in the western half of the aftershock zone and that the best estimate for the seismic moment is 50–100×1020 Nm. Using the tsunami waveforms, we estimated the source area of the 1957 tsunami by backward propagation. The tsunami source area is smaller than the aftershock zone and is about 850 km long. This does not include the Unalaska Island area in the eastern end of the aftershock zone, making this area a possible seismic gap and a possible site of a future large or great earthquake. We also inverted the tsunami waveforms for the slip distribution. Slip on the 1957 rupture zone was highest in the western half near the epicenter. Little slip occurred in the eastern half. The moment is estimated as 88×1020 Nm, orM
w
=8.6, making it the seventh largest earthquake during the period 1900 to 1993. We also compare the 1957 earthquake to the 1986 Andreanof Islands earthquake, which occurred within a segment of the 1957 rupture area. The 1986 earthquake represents a rerupturing of the major 1957 asperity. 相似文献
15.
Simulation of strong earthquake characteristics of a scenario earthquake (MS7.5) based on the enlightenment of 2022 MS6.9 earthquake in Menyuan 下载免费PDF全文
下载免费PDF全文 The Menyuan area is an important transportation hub in the Hexi Corridor. The Menyuan MS6.9 earthquake that occurred on January 8, 2022 had a major impact on the local infrastructure and transportation of this region. Due to the high possibility of similar strong earthquakes occurring in this area in the future, preliminary assessment of the seismic intensity characteristics of destructive earthquakes in this region is essential for effective disaster control. This paper uses the empirical Green′s function (EGF) method as a numerical simulation tool to predict the ground motion intensity of Datong Autonomous County under the action of the scenario earthquake (MS7.5). Seismic records of aftershocks of the 2016 Menyuan MS6.4 earthquake were used as Green’s functions for this simulation. The uncertainties associated with various source parameters were considered, and 36 possible earthquake scenarios were simulated to obtain 72 sets of horizontal ground motions in Datong County. The obtained peak ground acceleration (PGA) vs. time histories of the horizontal ground motion were screened using the attenuation relationships provided by the fifth-edition of China's Seismic Ground Motion Parameter Zoning Map and the NGA-West2 dataset. Ultimately, 32 possible acceleration-time histories were selected for further analysis. The screened PGA values ranged from 78.8 to 153 cm/s2. The uncertainty associated with the initial rupture point was found to greatly affect the results of the earthquake simulation. The average acceleration spectrum of the selected acceleration-time history exceeded the expected spectrum of a intermediate earthquake, which means that buildings in Datong County might sustain some damage should the scenario earthquake occur. This research can provide reliable ground motion input for urban earthquake damage simulation and seismic design in Datong County. Growing the dataset of small earthquakes recorded in this region will facilitate the large-scale simulation of ground motions under different earthquake scenarios. 相似文献
16.
《地震研究进展（英文）》2021,1(4):100065
The focal mechanism solution of the Shiqu MS 4.4 earthquake occurred on May 16th, 2017 in Sichuan Province is studied by the gCAP method using the waveform data from the regional seismic networks in Sichuan, Qinghai, Tibet and Gansu provinces. The strike/dip/dipping angle of the first nodal plane are 214°/80°/167° and those of the second nodal plane are 306°/77°/10°, the optimal centroid depth is 7.3 ± 0.6 km and the moment magnitude is MW 4.5. Furthermore, the study investigates the robustness of the results against the error of crustal velocity structure, location, data quality and difference of seismic parameters, subsequently obtaining a stable resolved focal mechanism. According to the geological structure in the seismogenic area, spatial distribution of aftershock sequenceof the regional tectonic stress field, and the focal mechanism of the main shock, we suggest that the Shiqu earthquake is induced by a left-lateral strike-slip mechanism and the second nodal plane is inferred to be the seismogenic fault, consistent with the geometry of the Changshagongma fault which is the secondary fault of the northwest part of the Xianshuihe fault zone. 相似文献
17.
Wei-feng Liang Yun-feng Zhao Yun-ma Xu Yi-qing Zhu Shu-song Guo Fang Liu Lian Liu 《地震科学（英文版）》2013,26(3-4):251-257
This paper introduces relative and absolute gravity change observations in the eastern portion of the Tibetan Plateau. We analyze and discuss a change that occurred in 2010 in the gravity along the eastern margin of the plateau and the relationship between this change and the 2013 Lushan M S7.0 earthquake. Our results show that: (1) before the Lushan M S7.0 earthquake, gravity anomalies along the eastern margin of the Tibetan Plateau changed drastically. The Lushan earthquake occurred at the bend of the high gradient zone of gravity variation along the southern edge of the Longmenshan fault zone. (2) The 2013 Lushan earthquake occurred less than 100 km away from the epicenter of the 2008 Wenchuan earthquake. Lushan and Wenchuan are located at the center of a four-quadrant section with different gravity anomalies, which may suggest that restoration after the Wenchuan earthquake may have played a role in causing the Lushan earthquake. (3) A medium-term prediction based on changes in gravity anomalies was made before the Lushan M S7.0 earthquake, in particular, a prediction of epicenter location. 相似文献
18.
At the beginning of the 21st century, a series of great earthquakes were recorded in northeastern Tibet, along the periphery of the Bayan Hara lithospheric block. An earthquake with MS = 8.1 occurred within the East Kunlun fault zone in the Kunlun Mountains, which caused an extended surface rupture with left-lateral strike slip. An earthquake with MS = 8 occurred in Wenchuan (China) on May 12, 2008, giving rise to an extended overthrust along the Lunmanshan fault zone. An earthquake with MS = 7.1 occurred in Yushu (China) on April 14, 2010; its epicenter was on the Grazze–Yushu–Funchuoshan fault; a left-lateral strikeslip offset was observed on the surface. An earthquake with MS = 7 occurred in the vicinity of Lushan on April 20, 2013; its epicenter was within the Lunmanshan fault zone, 103 km southwest of the zone of the catastrophic Wenchuan earthquake. An earthquake with MS = 8.2 occurred in Nepal on April 25, 2015. Based on the CSN seismic catalog, the energy of all earthquakes in eastern Tibet at the end of the 20th and beginning of the 21st centuries was estimated. It was found that Tibet was seismically quiet from 1980 to 2000. The beginning of the 21st century has been marked by seismic activation with earthquake sources migrating southward to surround the Bayan Hara lithospheric block from every quarter. Therefore, this block can be regarded as one of the most seismically active regions of China. 相似文献
19.
Qi Li Kai Tan Dong Zhen Wang Bin Zhao Rui Zhang Yu Li Yu Jie Qi 《Journal of Seismology》2018,22(3):805-814
The spatio-temporal slip distribution of the earthquake that occurred on 8 August 2017 in Jiuzhaigou, China, was estimated from the teleseismic body wave and near-field Global Navigation Satellite System (GNSS) data (coseismic displacements and high-rate GPS data) based on a finite fault model. Compared with the inversion results from the teleseismic body waves, the near-field GNSS data can better restrain the rupture area, the maximum slip, the source time function, and the surface rupture. The results show that the maximum slip of the earthquake approaches 1.4 m, the scalar seismic moment is ~ 8.0 × 1018 N·m (Mw?≈?6.5), and the centroid depth is ~ 15 km. The slip is mainly driven by the left-lateral strike-slip and it is initially inferred that the seismogenic fault occurs in the south branch of the Tazang fault or an undetectable fault, a NW-trending left-lateral strike-slip fault, and belongs to one of the tail structures at the easternmost end of the eastern Kunlun fault zone. The earthquake rupture is mainly concentrated at depths of 5–15 km, which results in the complete rupture of the seismic gap left by the previous four earthquakes with magnitudes >?6.0 in 1973 and 1976. Therefore, the possibility of a strong aftershock on the Huya fault is low. The source duration is ~ 30 s and there are two major ruptures. The main rupture occurs in the first 10 s, 4 s after the earthquake; the second rupture peak arrives in ~ 17 s. In addition, the Coulomb stress study shows that the epicenter of the earthquake is located in the area where the static Coulomb stress change increased because of the 12 May 2017 Mw7.9 Wenchuan, China, earthquake. Therefore, the Wenchuan earthquake promoted the occurrence of the 8 August 2017 Jiuzhaigou earthquake. 相似文献
20.
Yanyan Han Yang Zang Lingyuan Meng Yue Wang Shiguang Deng Yawei Ma Mengyu Xie 《地震研究进展（英文）》2022,2(3):100157
In this article, we review the general characteristics of seismicity in and around China and the overall statistics of earthquake damage in 2021, focusing on several significant events and related scientific topics. Among them, the largest event is the MS 7.4 Madoi earthquake in Qinghai Province, northwest China. The event marks another MS ?≥ ?7 earthquake occurring near the boundary of the Bayan Har Block that has ended a remarkable quiescence of the MS ?≥ ?7 earthquakes within the Chinese mainland. In addition, the MS 6.4 Yangbi earthquake in Yunnan Province, southwest China draws the most attention because of its abundant foreshocks, which are well recorded by the densely distributed seismic stations in the surrounding regions. Regarding this event, we review several recent publications focusing on the Gutenberg-Richter b-value change and the physical mechanism of foreshocks associated with this sequence. The MS 6.0 Luxian earthquake in Sichuan Province, southwest China has caused serious damage with a relatively low magnitude, partly because the focal depth of the mainshock is relatively shallow (3.5 ?km). It is another strong earthquake occurring within the southeast Sichuan basin with low historical seismicity yet has increased significantly since 2015, probably due to shale gas development and associated hydraulic fracturing. 相似文献