2022年青海门源M6.9地震矩心矩张量解

据中国地震台网中心测定,北京时间2022年1月8日01时45分,中国青海省海北州门源县发生了M6.9地震,震中位于( 37.77°N, 101.26°E),震源深度为10 km.这是2022年中国大陆第一个接近7级的强震.距离此次地震震中40 km以东,2016年曾发生过门源M6.4地震;且东北部在1927年还发生过甘...     

2010年4月14日青海玉树地震快速矩张量解

北京时间2010年4月14日7时49分37秒,在中国青海省玉树县发生了MW7.0地震.作者利用矩张量快速反演技术,通过反演全球台网的宽频带P波波形资料得到了这次地震的矩张量解,并判断走向119°、倾角83°、滑动角-2°的节面是本次地震的发震断层面.     

2010年1月12日海地地震快速矩张量解

2010年1月12日21点53分9秒协调世界时(UTC),在加勒比海域的海地发生了MW7.2地震.作者利用矩张量快速反演技术,通过反演全球地震台网的宽频带P波波形资料得到了这次地震的矩张量解,并判断走向253°、倾角74°、滑动角17°的节面是本次地震的发震断层面.     

2009年12月19日台湾花莲地震快速矩张量解

2009年12月19日13点2分16秒协调世界时(UTC),在台湾花莲海域发生了MW6.7地震.作者利用矩张量快速反演技术,通过反演全球地震台网的宽频带P波波形资料得到了这次地震的矩张量解,并判断走向4°、倾角75°、滑动角76°的节面是本次地震的发震断层面.     

2014 年新疆于田MS 7. 3 地震矩心矩张量快速测定

基于中国大陆中强震自动矩张量测定系统,采用虚拟中国地震台网记录的近震波形(震中距4° ～ 12°),反演了新疆于田MS7. 3 地震的矩心矩张量。结果显示,地震发震断层面参数分别为走向243° /倾角70° /滑动角－ 18°,表现为1 次左旋走滑为主兼有少量正倾滑分量的事件。矩心在水平方向上位于震中(36. 123°N,82. 499°E)以东约13 km,矩心深度约10 km。总标量地震矩M0为3. 05 × 1019N·m,换算成矩震级MW6. 92,推断震源破裂时大部分能量释放的持续时间约14s。同时探讨了自动矩张量测定系统在未来地震灾情预判中的重要作用。     

矩震级及震源机制相似地震的辐射能量差别——2014年鲁甸地震与景谷地震宽频带体波震级的比较

2014年8月3日鲁甸地震和10月7日景谷地震具有相似的矩震级和震源机制,但所造成的灾害却相差甚远。为考察地震辐射能量在这两次地震致灾过程中的作用,本文利用震中距6°~80°范围内记录了鲁甸地震的142个台站、记录了景谷地震的138个台站的宽频带地震记录,计算了累积宽频带体波震级m_(Bc)。结果表明鲁甸地震的m_(Bc)高于景谷地震,因此地震辐射能量的差别对解释两次地震灾害的差别有不可忽视的作用。     

天山地震带境内外主要断层滑动速率和地震矩亏损分布特征研究

本文搜集、整理1998—2013年境内外天山及周边地区(包括中国新疆、哈萨克斯坦、吉尔吉斯斯坦等)500余个GPS观测点数据,采用GAMIT/GLOBK软件对其进行解算和平差计算,并利用了弹性块体模型计算区域块体边界断层闭锁深度、块体运动参数和主要活动断层的滑动速率.研究结果表明,东、西昆仑地震带闭锁深度最大(19km),其次为南天山地区,闭锁深度达到17km,闭锁深度最小的为哈萨克斯坦(13km);各块体相对欧亚板块作顺(逆)时针旋转,旋转速率最大(-0.7208±0.0034°/Ma)为塔里木块体,其围绕欧拉极(38.295±0.019°N,95.078±0.077°E)顺时针方向转动,旋转速率最小为天山东段(0.108±0.1210°/Ma),而天山东、西两段无论是在旋转速率上还是在旋转方向上都有显著的区别.西昆仑断裂带的滑动速率(10.2±2.8mm·a-1)最大,南天山西段滑动速率为9.5±1.8mm·a-1,其东段为3.9±1.1mm·a-1;而北天山东段滑动速率(4.7±1.1mm·a-1)高于北天山西段(3.7±0.9mm·a-1);塔里木盆地南缘的阿尔金断裂带平均滑动速率为7.6±1.4mm·a-1,其结果与阿勒泰断裂带滑动速率(7.6±1.6mm·a-1)基本相当;天山断裂带运动方式主要以挤压为主,而阿尔金、昆仑、阿尔泰以及哈萨克斯坦断裂带均是以走滑运动方式为主,除阿勒泰断裂带走滑方式为右旋以外,其余几个断裂带均为左旋运动.最后,利用主要断裂带的滑动速率计算出各地震带的地震矩变化率以及1900年以来地震矩累计变化量,其结果与利用地震目录计算所得到的地震矩进行比较,判定出各地震带上地震矩均衡分布状态,研究结果显示阿尔金、西昆仑、东昆仑和北天山东段断裂带存在较大的地震矩亏损,均具有发生7级以上地震的可能性,南天山东段和哈萨克斯坦断裂带地震矩亏损相对较小,具有孕育6~7级地震的潜能,而天山西段、阿勒泰地震矩呈现出盈余状态,不具在1~3年内有发生强震的可能.     

2012年5月3日甘肃金塔MS5.4地震矩张量反演

使用甘肃省测震台网记录的三分向宽频带长周期数字波形资料,在时间域反演2012年5月3日甘肃金塔5.4级地震的矩张量解,并与Harvard大学CMT解进行比较。结合该地区的地质资料和构造背景,分析金塔地震的发震成因。结果显示震源性质为走滑型,断层破裂面走向为166°、倾角66°、滑动角-168°,P轴走向为32°,与金塔地震余震分布和地震破坏分布情况大体一致,由此推测金塔地震的发震断层可能为神螺山-野马井断层。     

2021年2月13日日本本州东海岸MW7.2地震矩心矩张量解

根据美国地质调查局(United States Geological Survey,缩写为USGS)国家地震信息中心(National Earthquake Information Centre,缩写为NEIC)的测定,2021 年2 月13 日14 时7 分50 秒( UTC) ,日本本州以东发生了一次矩震级高达 M...     

基于W震相技术的全球强震(MW≥6.5)矩心矩张量自动反演系统评估

使用最近构建的虚拟全球地震台网记录的波形数据,采用OpenMP的并行编程技术优化原有算法, 研制了基于W震相技术的全球强震(M_W≥6.5)矩心矩张量自动反演系统.为了评估该系统的准确度和时效性,将离线自动测定的2008年1月—2013年7月全球140次地震(M_W6.5—9.0)的矩心矩张量与全球矩心矩张量工作组(GCMT)的结果进行了比较.结果表明:该系统可准确测定全球M_W≥6.5地震的矩张量,绝大多数地震矩震级与GCMT给出的矩震级呈现出良好的线性趋势,两者之差ΔM_W的标准方差约0.13,ΔM_W位于区间(-0.2,0.2)的地震占总数的96%;地震矩6个分量分别与GCMT相应的结果沿对角线近线性分布,多数地震矩心水平位置与GCMT给出的矩心水平位置比较接近,两者间大圆弧距离位于区间(0,50km)的地震次数占总数的84%;在台站覆盖较均匀的条件下,该系统能够实现震后25—40分钟自动准确测定全球M_W≥6.5地震的矩心矩张量.      

强震观测网、高灵敏度地震观测网、地中强震观测网、宽频带地震观测网

阪神·淡路大震灾后 ,日本着手对原有的地震观测体制作彻底改革 ,多项全国性配置地震计的计划同时开始启动。地震引起的地面晃动的程度不尽相同 ,无感微小地震引发的晃动仅有 0 .0 0 1 μm,频率为1 0 Hz;巨大地震引起的地面晃动的幅度高达 2～ 3 m,周期也有几十秒。虽说都称之为地震计 ,但由于地震动的振幅和频率涉及的范围太大 ,所以应针对观测对象选用不同类型的地震计。下面介绍不同类型的观测网。1　强震观测网 ( K- NET)无论大地有多大的晃动都能将其准确记录下来的地震计称之为强震计。它构造坚实 ,信号明确 ,通常设置在地表 ,对了…     

Age, geology, geophysics, and geochemistry of Mahukona Volcano, Hawai`i

The size, shape, and magmatic history of the most recently discovered shield volcano in the Hawaiian Islands, Mahukona, have been controversial. Mahukona corresponds to what was thought to be a gap in the paired sequence (Loa and Kea trends) of younger Hawaiian volcanoes (<4?Ma). Here, we present the results of marine expeditions to Mahukona where new bathymetry, sidescan sonar, gravity data, and lava samples were collected to address these controversies. Modeling of bathymetric and gravity data indicate that Mahukona is one of the smallest Hawaiian volcanoes (～6,000?km³) and that its magmatic system was not focused in a long-lived central reservoir like most other Hawaiian volcanoes. This lack of a long-lived magmatic reservoir is reflected by the absence of a central residual gravity high and the random distribution of cones on Mahukona Volcano. Our reconstructed subsidence history for Mahukona suggests it grew to at least ～270?m below sea level but probably did not form an island. New ⁴⁰Ar–³⁹Ar plateau ages range from 350 to 654?ka providing temporal constraints for Mahukona’s post-shield and shield stages of volcanism, which ended prematurely. Mahukona post-shield lavas have high ³He/⁴He ratios (16–21?Ra), which have not been observed in post-shield lavas from other Hawaiian volcanoes. Lava compositions range widely at Mahukona, including Pb isotopic values that straddle the boundary between Kea and Loa sequences of volcanoes. The compositional diversity of Mahukona lavas may be related to its relatively small size (less extensive melting) and the absence of a central magma reservoir where magmas would have been homogenized.     

The Yecheng,Xinjiang, China,earthquake of February 14, 1980

In this study, we have checked the location and focal depth of the Yecheng earthquake (m _b = 6.0, maximum intensity VII) of February 14, 1980. The result shows that this is an intermediate event with a focal depth of 90 km. The microepicenter is located at 36. 4°N, 76, 9°E, while the macroepicenter is at 37.3°N, 76.9°E, 90 km to the north of the microepicenter. This is the first destructive intermediate event in China which led to a damage as severe as of intensity VII. The focal mechanism of the event is determined to be of thrust type. Combined with the analysis of seismological and geological data in surrounding area, the possible relation between the event and plate movement has been discussed. The result in this paper indicates that in some particular place, the destructive effect of intermediate event should be considered in seismic hazard assessment.     

Sun, climate, hunger, and mass migration

Paleoclimatic studies indicate four epochs of global cooling during the last 4 000 years, i. e. during the few centuries before and after 2000 BC, 800 BC, 400 AD, and 1 600 AD; the quasiperiodicity corresponds to cyclic variation of solar activity. Global temperature changes influenced regional precipitation patterns: Northern Europe was wetter while the middle- and low-latitude lands were more arid during colder epochs. Both sets of cold climatical conditions were unfavorable for agricultural production. Historical records show that large demographic movements in history took place because of crop failures and mass starvation, rather than escaping from war zones. The “wandering” of the Germanic tribes during the first two or three centuries of the Christian Era is one example. Whereas the accelerated release of carbon dioxide from the burning of fossil fuels is ultimately to cause global warming, historical evidence indicates, however, that global warming has been on the whole a blessing to mankind. Global cooling, on the other hand, has curtailed agricultural production and has led to famines and mass migrations of people. Perhaps the most important task at the present is not so much computer-modelling of greenhouse effect on global climate, but water-management and agricultural researches to insure food-supply for an everincreasing world population.     

Physical properties,vitrinite reflectance,and microstructure of coal,Taiyuan Formation,Qinshui Basin,China

In this study, we experimentally established the relationship between physical properties, vitrinite reflectance, and microstructure of coal, Taiyuan Formation, Qinshui Basin, China using representative coal samples collected from three different mines via the rock mechanics testing system (MTS). We analyzed the organic macerals, vitrinite reflectance, and microstructure of 11 coal samples using petrography and scanning electron microscopy (SEM). The experimental results suggest that (1) the elastic parameters can be described by linear equations, (2) both P-and S-wave velocities display anisotropy, (3) the anisotropy negatively correlates with vitrinite reflectance, and (4) the acoustic velocities and Young’s modulus are negatively correlated with the volume of micropores. The derived empirical equations can be used in the forward modeling and seismic inversion of physical properties of coal for improving the coal-bed methane (CBM) reservoir characterization.     

Spatial distribution,source apportionment,and associated risks of trace metals (As,Pb, Cr,Cd, and Hg) from a subtropical river,Gomti, Bangladesh

Sediment samples from the Gomti River basin were investigated to determine and evaluate trace metal concentrations,their biological effect,and potential ecological and human health risks for adults and children.The mean concentrations of trace metals were organized in the descending order of mercury(Hg)(0.08 mg/kg)>chromium(Cr)(0.06 mg/kg)>lead(Pb)(0.05 mg/kg)>arsenic(As)(0.02 mg/kg)>cadmium(Cd)(0.01 mg/kg).The current study illustrated that metals were attributed to the area from natural sources and different anthropogenic sources especially from industries.However,the concentration levels were lower than the sediment quality guidelines(SQGs)based on the effect-range classifications of threshold effect concentration(TEC)and probable effect concentration(PEC).Therefore,the concentration of the elements showed no adverse biological effects on aquatic organisms.The evaluated potential ecological risk index also revealed the low toxicity to the aquatic environment.Moreover,the applied sediment quality indices,geo-accumulation index(Igeo),contamination factor(CF),and contamination severity index(CSI)suggested that the contamination levels of the elements were in the acceptable range,and the contamination had not notably impacted on the sediment quality.The risk index(HI)concerning age groups was significantly less than the threshold limit of 1 indicating that the contamination had no non-carcinogenic risk effect.The total carcinogenic risk(TCR)was less than a risk value of 1×10⁴.Hence,the current study suggests that immediate remediation is not required due to an absence of alarming conditions in the study area.Proper monitoring of the attribution of the metal elements should be done for the betterment of human and environmental health。     

山西高平地震

阐述了发生在山西高平的地震和对高平有影响的地震，分析了高平市的地震灾害，通过分析得出高平地震与晋获断裂带活动有关的结论。