共查询到20条相似文献，搜索用时 185 毫秒
1.
2.
在已有的凹凸体震源模型基础上考虑凹凸体位错非均匀性,提出改进的凹凸体位错模式.新的位错模式随机设置凹凸体上各子断层位错量,同时在凹凸体与背景区交界处设置位错平缓变化的区域.以1989年美国 LomaPrieta地震为例,计算不同断层位错模式下引起的地表位移,并与反演得到真实情况下地表的位移作对比,验证改进凹凸体位错模式的可靠性.结果显示,使用改进的渐变凹凸体非均匀位错模式计算时,与真实情况下竖向地表位移差大于8cm 的区域面积为 43km2,相较凹凸体均匀位错模式缩减25%;水平地表位移差大于8cm 区域面积为117km2,相较凹凸体均匀位错模式缩减达31%.利用改进的渐变凹凸体非均匀位错模式,计算1679年三河—平谷大地震在北京地区形成的地表位移场.北京市外,最大竖向地表位移大于4．8m,最大水平地表位移大于2．6m,均出现在三河附近;北京市内,通州区至平谷区一带地表位移最大,最大水平地表位移大于 2．6m,最大竖向地表位移大于1m.研究结果可为今后北京地区的抗震设防提供参考. 相似文献
3.
孔隙压岩石三轴摩擦实验装置是研究孔隙压对岩石滑动面摩擦性状影响的专用设备.该设备包括孔隙压岩石三轴实验装置和岩石摩擦装置两部分.摩擦装置由上、下压头,密封套筒和具有内部滑动块体的岩石样品组成.滑动面宽20×20mm、高40mm 的长方体,滑动面宽20mm、高30mm.最大孔隙压P_(max)=100MPa,最大位移L_(max)=10mm.应用该装置将三轴条件下样品之间的斜向摩擦滑动变为轴向滑动.滑动面上的法向压力σ_n=σ_3,即σ_n 变为与轴压无关的独立变量. 相似文献
4.
利用日本ALOS-2和欧空局Sentinel-1A卫星获得的尼泊尔地震同震形变场,结合GPS同震位移数据,联合反演了断层滑动分布特征和空间展布.结果表明:尼泊尔地震的同震形变场主要集中在150km×100km的范围内,且分为南北两个相邻的形变中心,南形变中心的视线向抬升量约为1.2m,北形变中心的视线向沉降量约为0.8m,均位于发震断层上盘.位于形变抬升区的KKN4和NAST两个GPS站,抬升量和南向运动量均达到了m级,而远离震区的其他GPS台水平和垂直观测量均在1cm以内.联合反演得到的断层位错分布主要集中在沿走向150km,沿倾向70km的范围内,最大滑动量为5.59m,平均滑动量为0.94m.断层面倾角在浅部约为7°,随着深度增加,倾角逐渐变大,到垂直深度20km时倾角接近12°;5月12日MW7.2级余震位于主震破裂区的"凹"型滑动缺损区域;主震破裂区的上边界与MBT空间位置十分吻合,主震破裂区主要集中的MBT以北50~60km处,垂直深度为8~9km,倾角为9°,继续向北时主震破裂面以10°~12°的倾角向深延伸,在18~20km可能与MHT交汇.因此,初步判定MBT为此次地震的发震断层. 相似文献
5.
简要介绍了合成孔径雷达干涉测量技术、差分干涉雷达测量技术，并对干涉测量精度进行了简单讨论．以西藏玛尼地区为例，通过三通差分干涉处理，获取了玛尼地震同震形变场.结果表明:形变场长200 km、宽115 km．干涉条纹以北东东向发震断层——玛尔盖茶卡断层为中心分布，且基本与发震断层平行；通过对干涉形变图进行分析，发震断层可分为3段，其中西段长约23 km，中段长约60 km，东段长约26 km，整个发震断层共长110 km；震中附近最大隆起斜距向位移量为162.4 cm，断层西侧最大沉降斜距向位移量为103.6 cm，震中最大地面水平位错为7.96 m． 相似文献
6.
本文以龙滩水库为例,根据库区地质构造、深部速度结构及数字地面高程,建立了库区三维有限元模型,基于孔隙弹性理论计算了水库蓄水过程中库底断层和围岩体孔隙压力、有效附加正应力、剪应力和库伦应力的动态变化,并结合水库蓄水后库区地震活动时空分布的特征,讨论了RIS时空演化与库水加卸载及渗透过程的动态响应关系及其可能的成因机制.结果表明：（1） 龙滩水库蓄水后地震活动呈现出明显的丛集性,主要分布在罗妥（丛Ⅰ）、八茂（丛Ⅱ）、拉浪（丛Ⅲ）、坝首（丛Ⅳ）和布柳河（丛Ⅴ）5个水库蓄水后淹没的深水区,这些区域也恰恰是库水加卸载及渗透过程中ΔCFS增加最明显的区域,而ΔCFS的影区几乎没有地震发生,表明水库蓄水后库区地震活动与ΔCFS的变化密切相关.（2） 在水库蓄水过程中,与水库有直接水力联系且渗透性较好的断裂成为地表水体附加水头压力向深部扩散的优势通道,沿此通道附加水头压力扩散的最大深度达13 km左右,震旦系-古生界以碳酸盐岩为主的地层成为附加水头压力扩散的主体层位,这与蓄水后库区中、小地震震源深度均小于13 km,且优势分布在5~10 km的特征相吻合,表明由于孔隙压力的存在降低了岩石的抗剪强度,同时部分抵消了围压的影响,致使该层位的岩体易于产生脆性破坏从而诱发地震活动.（3） 无论是深部还是浅部,各丛地震密集发生的时段绝大部分与相应深度ΔCFS加速升高或阶段性高值时段相重叠,可能说明在库水位快速抬升或阶段性高值时段,受外部荷载加载速率快速升高的影响,库底岩体和断层、裂隙等结构面更容易实现失稳扩展;深、浅部地震响应时间、活动频度和强度的差异可能与不同层位岩体力学性质及渗透性能的不均匀性有关.（4） 各丛地震诱发的物理力学机制有所不同.丛Ⅰ、丛Ⅱ、丛Ⅲ地震的诱发可能与库体重力荷载、孔隙压力扩散和库水浸润弱化3种作用都有关;丛Ⅳ地震的诱发主要受控于库体重力荷载作用,孔隙压力扩散和库水浸润弱化不起主导作用;丛Ⅴ地震的诱发主要受孔隙压力扩散和库水浸润弱化作用的影响,库体重力荷载作用一定程度上抑制了地震的发生. 相似文献
7.
利用差分干涉雷达测量技术获取的宏观震中区的同震形变场，结合对地震活动性、震源机制、野外考察等资料分析，对昆仑山口西8.1级地震同震形变场特征进行了研究. 结果表明:宏观震中位于库赛湖东北侧，宏观震中区发震断层可分为两个形变中心区域，其中西段长约42 km，东段长约48 km，整个发震断层主破裂段长90 km；由干涉形变条纹分布格局可清楚地判断出发震断层的左旋走滑特征；断层两盘变形特征不同，南盘变形程度明显大于北盘；宏观震中附近最大斜距向位移量为288.4 cm，最小斜距向位移量为224.0 cm，宏观震中发震断层最大左旋水平位错为738.1 cm，最小地面左旋水平位错为551.8 cm. 相似文献
8.
基于Sentinel-1 SAR升、降影像,利用D-InSAR技术获取新疆伽师M S6.4地震的同震形变场,结果表明,本次地震引起的同震形变场整体呈近椭圆状分布,形变区东西长约66 km,南北宽约40 km,整个形变场由南部隆升区和北部沉降区组成,南部最大隆升量约7 cm,北部最大沉降量约3 cm。本次地震发生在块体俯冲界面处的低倾角逆冲推覆构造带上,隆升和沉降两个中心均位于逆冲推覆体的上盘,形变主要以隆升形变为主,符合低倾角逆断层中强震的变形特征。在沉降区与隆升区之间干涉条纹连续分布,未出现表征地表破裂位置的空间失相关带,表明地震未引起明显的地表破裂。结合震源机制、余震精定位及区域构造特征,初步推断认为伽师地震的发震构造可能为柯坪塔格推覆构造前缘的N倾的柯坪断裂。 相似文献
9.
利用改进的自动经验基线校正方法SMBLOC,对2016年8月24日意大利佩鲁贾MW 6.2级地震震中周围约60 km内的近场强震记录进行基线校正并尝试给出同震位移场,与GPS观测结果进行对比分析,分别独立和联合两种资料反演震源滑动模型,并根据震源模型进一步给出全空间预测位移场分布.研究结果表明:(1)两种不同的资料给出的水平位移场幅值均为cm级,且均表明断层的错动以正断为主.(2)两种同震位移场分别独立和联合反演所得的震源静态滑动范围基本一致,最大滑动均发生在震中东北侧,强震模型表现出明显的双事件特征,较大滑动分布在震中东北侧和东南侧,GPS模型在震中东南侧的滑动相对较小,其双事件特征不明显.两种模型的最大滑动量分别为0.96 m和0.86 m,较为一致,反演的矩震级均在MW 6.3左右.(3)根据震源滑动模型计算所得的佩鲁贾地震全空间预测的水平同震位移场中最大位移分布区域与震后报告中受灾严重的地区基本一致.表明在一定的条件下,利用SMBLOC方法解算震级较小的MW 6.0左右地震强震记录的同震位移场,并反演震源滑动模型具有一定的可行性,且其同震位移场和滑动模型可为震后灾害快速评估、救援力量分配、余震趋势判定等快速应急响应工作提供参考依据. 相似文献
10.
2008年10月5日在新疆乌恰地区39.50°N、73.64°E处发生MW6.7地震,用ROI_PAC软件处理4景日本ALOS卫星数据得到乌恰地震的三维同震形变场。距离向,断层北侧最大位移达39 cm,南侧最大位移达36 cm;方位向,北侧和南侧的最大位移分别为1.5 m和2 m。采用Okada弹性位错模型分析该地震的滑动分布,模拟得出的断层走滑角为48°,倾滑角为53°,深度为10.5 km,最大形变量2.5 m,分析得出该地震为向北逆冲兼左旋走滑。 相似文献
11.
An Assessment of the Seismicity of the Bursa Region from a Temporary Seismic Network 总被引：2，自引：0，他引：2
A temporary earthquake station network of 11 seismological recorders was operated in the Bursa region, south of the Marmara
Sea in the northwest of Turkey, which is located at the southern strand of the North Anatolian Fault Zone (NAFZ). We located
384 earthquakes out of a total of 582 recorded events that span the study area between 28.50–30.00°E longitudes and 39.75–40.75°N
latitudes. The depth of most events was found to be less than 29 km, and the magnitude interval ranges were between 0.3 ≤ ML ≤ 5.4, with RMS less than or equal to 0.2. Seismic activities were concentrated southeast of Uludag Mountain (UM), in the
Kestel-Igdir area and along the Gemlik Fault (GF). In the study, we computed 10 focal mechanisms from temporary and permanents
networks. The predominant feature of the computed focal mechanisms is the relatively widespread near horizontal northwest-southeast
(NW–SE) T-axis orientation. These fault planes have been used to obtain the orientation and shape factor (R, magnitude stress ratio)
of the principal stress tensors (σ1, σ2, σ3). The resulting stress tensors reveal σ1 closer to the vertical (oriented NE–SW) and σ2, σ3 horizontal with R = 0.5. These results confirm that Bursa and its vicinity could be defined by an extensional regime showing a primarily normal
to oblique-slip motion character. It differs from what might be expected from the stress tensor inversion for the NAFZ. Different
fault patterns related to structural heterogeneity from the north to the south in the study area caused a change in the stress
regime from strike-slip to normal faulting. 相似文献
12.
Truncation of the distribution of ground-motion residuals 总被引：4，自引：3，他引：1
Recent studies to assess very long-term seismic hazard in the USA and in Europe have highlighted the importance of the upper
tail of the ground-motion distribution at the very low annual frequencies of exceedance required by these projects. In particular,
the use of an unbounded lognormal distribution to represent the aleatory variability of ground motions leads to very high
and potentially unphysical estimates of the expected level of shaking. Current practice in seismic hazard analysis consists
of truncating the ground-motion distribution at a fixed number (ε
max) of standard deviations (σ). However, there is a general lack of consensus regarding the truncation level to adopt. This paper investigates whether
a physical basis for choosing ε
max can be found, by examining records with large positive residuals from the dataset used to derive one of the ground-motion
models of the Next Generation Attenuation (NGA) project. In particular, interpretations of the selected records in terms of
causative physical mechanisms are reviewed. This leads to the conclusion that even in well-documented cases, it is not possible
to establish a robust correlation between specific physical mechanisms and large values of the residuals, and thus obtain
direct physical constraints on ε
max. Alternative approaches based on absolute levels of ground motion and numerical simulations are discussed. However, the choice
of ε
max is likely to remain a matter of judgment for the foreseeable future, in view of the large epistemic uncertainties associated
with these alternatives. Additional issues arise from the coupling between ε
max and σ, which causes the truncation level in terms of absolute ground motion to be dependent on the predictive equation used. Furthermore,
the absolute truncation level implied by ε
max will also be affected if σ is reduced significantly. These factors contribute to rendering a truncation scheme based on a single ε
max value impractical. 相似文献
13.
Song-Yan Song Xue-Song Zhou Chun-Yong Wang Xian-Kang Zhang Jian-Li Song Yi Gong 《地震学报(英文版)》1997,10(1):15-25
On the basis of S wave information from Tai’an-Xinzhou DSS profile and with reference to the results from P-wave interpretation,
the 2-D structures, including S-wave velocity V
s, ratio γ between V
p and V
s; and Poisson’ s ratio σ, are calculated; the structural configuration of the profile is presented and the relevant inferences are drawn from the
above results. Upwarping mantle districts (V
s≈4.30 km/s) and sloping mantle districts (V
s≈4.50 km/s) of the profile with velocity difference about −4% at the top of upper mantle are divided according to the differences
of V
s, γ and σ in different media and structures, also with reference to the information of their neighbouring regions; the existence of
Niujiaqiao-Dongwang high-angle ultra-crustal fault zone is reaffirmed; the properties of low and high velocity blocks (zones)
including the crust-mantle transitionalzone and the boudary indicators of North China rift valley are discussed. A comprehensive
study is conducted on the relation of the interpretation results with earthquakes. It is concluded that the mantle upwarps,
thermal material upwells through the high-angle fault, the primary hypocenter was located at the crust-mantle juncture 30.0∼33.0
km deep, and additional stress excited the M
S=6.8 and M
S=7.2 earthquakes at specific locations around 9.0 km below Niujiaqiao-Dongwang, the earthquakes took place around the high-angle
ultra-crustal fault and centered in the brittle media and rock strata with low γ and low σ values.
This subject is part of the 85-907-02 key project during the “8th Five-Year Plan” from the State Science and Technology Commission. 相似文献
14.
Summary The periods, the maximum absolute displacement amplitudes and the maximum particle velocities of the surface waves, propagating in the weathered layer are investigated. Dependences of the parameters under discussion on the distance r (km) between sites and shot points are expressed for distances from 3.6 to 38.6 km by the functions: T(s)=0.40r
0.30
, A
max
(m)==502.73r
–1.93
and v
max
(mm s
–1)=7.95
r
–2.22. 相似文献
15.
ＥｓｔｉｍａｔｉｏｎｏｆｓｅｉｓｍｉｃｓｔｒｅｓｄｒｏｐｆｒｏｍｔｈｅｐｅａｋｖｅｌｏｃｉｔｙｏｆｇｒｏｕｎｄｍｏｔｉｏｎＪＩＡＺＨＥＮＧＱＩＮ（秦嘉政）ＺＵＹＩＮＬＩＵ（刘祖荫）ＸＩＡＯＤＯＮＧＱＩＡＮ（钱晓东）ＱＩＮＧＹＩＮＸＩＥ（谢庆... 相似文献
16.
Modern tectonic stress field in the Chinese mainland inverted from focal mechanism solutions 总被引：1，自引：0，他引：1
IntroductionTheinversionapproachofregionalstressfielddevelopedinrecent10to20yearsprovidesausefultoolforstudyingthemeanstressinagivenregion(Angeller,1979;Ellsworth,1981,Xu,Ge,1984).Becauseitusesmultitudinousfaultsinsteadofsinglefault,itcanremovetheinhomogeneityoflocalmediumsoastorevealtheregionalstressinformation.Besides,thismethodproducesaRvalue,whichisdefinedby(O-2--q)/(q--q),andmaydescribestherelativemagnitUdeofintermediateprincipalstress,whereq,acand%arethemaximum,theintermediateandthemi… 相似文献
17.
Ａｌｉｇｎｍｅｎｔｓｉｌｋｗｏｒｍｓａｓｓｅｉｓｍｉｃａｎｉｍａｌａｎｏｍａｌｏｕｓｂｅｈａｖｉｏｒ（ＳＡＡＢ）ａｎｄｅｌｅｃｔｒｏｍａｇｎｅｔｉｃｍｏｄｅｌｏｆａｆａｕｌｔ：ａｔｈｅｏｒｙａｎｄｌａｂｏｒａｔｏｒｙｅｘｐｅｒｉｍｅｎｔＭＯＴＯ... 相似文献
18.
ＩｎｆｌｕｅｎｃｅｃａｕｓｅｄｂｙｉｎｉｔｉａｌｔｅｃｔｏｎｉｃｓｔｒｅｓｏｎｒｅｌａｔｉｖｅｍｅａｓｕｒｅｍｅｎｔｏｆｂｏｒｅｈｏｌｅｇｒｏｕｎｄｓｔｒｅｓｉｎｖｉｓｃｏｅｌａｓｔｉｃｍｅｄｉａＰＥＮＧ－ＪＵＮＺＨＡＯ１）（赵鹏君），ＪＩＡＮ－Ｗ... 相似文献
19.
Uplift of a broad area centered ~6 km west of the summit of South Sister volcano started in September 1997 (onset estimated
from model discussed in this paper) and was continuing when surveyed in August 2006. Surface displacements were measured whenever
possible since August 1992 with satellite radar interferometry (InSAR), annually since August 2001 with GPS and leveling surveys,
and with continuous GPS since May 2001. The average maximum displacement rate from InSAR decreased from 3–5 cm/yr during 1998–2001
to ~1.4 cm/yr during 2004–2006. The other datasets show a similar pattern, i.e., surface uplift and extension rates decreased
over time but deformation continued through August 2006. Our best-fit model to the deformation data is a vertical, prolate,
spheroidal point-pressure source located 4.9–5.4 km below the surface. The source inflation rate decreased exponentially during
2001–2006 with a 1/e decay time of 5.3 ± 1.1 years. The net increase in source volume from September 1997 to August 2006 was 36.5–41.9 x 106 m3. A swarm of ~300 small (M
max = 1.9) earthquakes occurred beneath the deforming area in March 2004; no other unusual seismicity has been noted. Similar
deformation episodes in the past probably would have gone unnoticed if, as we suspect, most are small intrusions that do not
culminate in eruptions. 相似文献
20.
Gerassimos A. Papadopoulos Hiroyuki Matsumoto Athanassios Ganas Vassilis Karastathis Spyros Pavlides 《Journal of Seismology》2004,8(3):381-394
The static displacement field of the Athens 1999 earthquake has been numerically modeled by a BEM method and analysed from SAR interferometry images with compatible results: (a) for a fault that reaches the surface the subsidence field coincides with the hangingwall domain of the Fili neotectonic normal fault with maximum amplitude, d
max, 5.5–7 cm, which is consistent with the possibly co-seismic displacement of 6–10 cm observed in the field, the average fault dislocation of 5–8 cm found by the application of circular source models, and the displacement up to 6 cm predicted by empirical relations between magnitude and displacement; the field of uplift covers the footwall domain of the fault with d
max1.5 cm;d gradually decreases with distance from the fault at a gradient of 0.4 cm/km, (b) for a blind fault d
max is only 1.8 and 0.3 cm in the hangingwall and footwall, respectively, and the decay gradient becomes 0.15 cm/km, (c) the total deformation area is 15 km × 15 km and the Fili fault, with a preferred mean dip of 60°, constitutes the natural boundary between the subsidence and uplift areas. The macroseismic field pattern is similar with that of the static ground deformation. The majority of intensity values VI (MM and EMS-98 scales), are distributed within the hangingwall of the Fili fault, while the highest intensities (VIII and IX) concentrate very close to the Fili fault within its hangingwall domain. A gradual decrease of the intensities with the distance from the Fili fault is evident. Because of the similarity between the intensity distribution pattern and the static ground deformation pattern, we make the hypothesis that the latter predicts well enough the main characteristics of the former although the ground displacement is dominated by relatively low frequency as compared to the ground acceleration. 相似文献