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1.
本文联合使用云南、四川和贵州地震台网的85个地震台站在2008年1月—2017年12月期间记录的49130个地震、317366个初至Pg震相绝对到时数据和2674110条高精度的相对到时数据,采用区域双差地震层析成像方法联合反演了川滇南部地壳三维P波速度结构和39621个地震的震源参数,探究了川滇南部中下地壳流和腾冲火山区岩浆囊的分布特征.研究结果表明：（1）川滇南部上地壳的速度异常特征与地表地形密切相关;（2）小江断裂带的中下地壳存在一条绵延近二百多公里的低速异常结构,最南端受到红河断裂带的阻挡而终止于断裂带南段北侧,这可能是川滇南部的一条中下地壳流,低速异常结构在红河断裂带南段转而向南东流动反映了红河断裂带可能为川滇菱形块体的西南边界;（3）红河断裂带各段速度异常存在明显的差异,重定位后的震源分布显示红河断裂带中段和南段虽然不如北段地震活动强烈,但地震震源深度分布较北段深;（4）腾冲火山区西侧和北侧下方10~20 km深度范围内存在的低速异常体推测为通过怒江断裂带形成的岩浆通道从中地壳涌入上地壳的岩浆囊,可能反映了自更新世延续至今的以橄榄玄武岩和安山岩为主要岩性的壳内岩浆活动,持续的岩浆活动为地表热活动提供了主要动力. 相似文献
2.
现今地震活动性显示红河断裂带强震主要发生在断裂带的北段，中段长期存在地震空区.为了更好地理解红河断裂带不同段落地震活动性差异和评估未来潜在地震危险性，本研究基于分层半无限空间黏弹性地球模型计算了自1833年嵩明M8.0地震以来，红河断裂带上及其周边共25次强震由于同震应力阶变、震后黏滞松弛和震间构造应力加载的综合作用，红河断裂带上库仑应力变化的演化过程.结果表明，在近180年红河断裂带南北两段得到加载，中段始终位于应力影区，这可能部分解释红河断裂带南北段地震相对活跃、中段长期存在的地震平静现象.假设未来三十余年该地区不再发生大震，考虑震后和震间作用，红河断裂带中段应力影区仍然存在，但范围在缩小；洱源附近、大理至大斗门以北地区、元江以南地区应力增加超过0.1 MPa，可能仍是地震潜在危险区段. 相似文献
3.
应用粘弹性计算程序，计算1833年嵩明8.0级大地震产生的同震和震后应力场变化，并计算对附近的小江断裂带、安宁河断裂带、则木河断裂带及云南境内红河断裂带造成的同震和震后库仑应力变化。结果表明，嵩明8.0级大地震对滇中南地区应力分布产生较大影响，对周围断层的影响甚至持续数百年的时间。嵩明8.0级地震使震中附近的小江断裂中段、安宁河断裂南段和红河断裂带中段库仑应力减小，降低发震危险；而小江断裂带南北段、安宁河断裂北段、则木河断裂带和红河断裂带南北两段库仑应力增加，地震危险性增强。红河断裂带中段在数百年时间尺度内始终处于嵩明8.0级地震库仑应力的减小区域，该研究结果有助于解释此断裂段的地震平静现象。 相似文献
4.
云南地区地震精确定位及其构造意义分析 总被引：3，自引：1，他引：3
运用双差定位法，对云南区域数字地震遥测台网记录的1999—2003年云南地区ML≥1.0地震进行重新定位，得到3000多个地震的精确定位结果。重定位结果显示，在东经100。和103。线附近存在两个震源深度较深的区域，最深达50km，刚好对应金沙江一红河断裂带的北段和小江断裂带。这一结果一方面揭示出这两条深大断裂与地震活动之间存在密切关系，另一方面也表明重定位结果在震源深度和空间分布上都较以前有明显改善。同时，姚安、大姚地震序列的重定位结果也说明双差定位法是一种比较好的地震定位方法。 相似文献
5.
应用结合波形互相关技术的双差地震定位法对红河断裂带北段1999—2015年发生的地震进行重新定位。 重新定位后残差明显降低, 震中相比于定位前分布更为集中, 绝大部分地震位于5~15 km的中上地壳。 对重定位结果进行误差分析, 统计显示在95%置信水平下, 定位误差椭圆的长轴基本不超过2.6 km, 水平和垂直方向定位误差均为1.6 km, 定位结果具有较好的稳定性。 相似文献
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7.
2020年2月3日四川省成都市青白江区发生MS5.1地震,震中烈度为Ⅵ度。该地震事件震中位于龙泉山断裂带上,距离成都市中心38 km,是龙泉山断裂带历史上非常罕见的5.0级以上地震事件。针对该事件成因进行了综合分析与研究,具体内容包括:(1)通过收集历史地震资料讨论龙泉山断裂带的地震活动性;(2)利用高质量的波形数据对主震位置进行重定位;(3)根据地震层析成像获得的三维vP、vS以及泊松比(σ)模型分析了孕震构造和流体影响,以及(4)利用固体潮理论模型分析了固体潮与地震触发的相关性。结果表明,本次MS5.1地震发生在龙泉山断裂带北段,震中坐标为(30.732°N,104.529°E),震源深度为15.12 km;震源位于高-低泊松比过渡带附近,并伴随着大范围的低速异常,初步推断与深部流体有关;同时,固体潮在断层面上产生的剪切应力变化,也可能与本次地震的触发密切相关,暗示着在地震发生前龙泉山北段的地震危险性已经达到了较高水平。因此深部流体侵入作用、强震同震效应以及特定孕震构造环境的综合影响可能是导致本次地震触发的主要因素。 相似文献
8.
本文以青藏高原东南缘南段1999—2017年的GPS速度场为主,结合小震分布、历史地震和活断层探测等资料,首先,基于Okada断层位错模型反演了研究区域主要活断层的滑动速率;其次,以断层滑动速率和GPS速度场观测资料作为约束,利用DEFNODE负位错方法反演了研究区域的块体内部变形及主要活断层的闭锁程度和滑动亏损;最后,计算研究区域现今应变率场,并结合Pms和XKS剪切波分裂结果,探讨分析了青藏高原东南缘的动力学特征.研究结果表明:(1)红河断裂带现今滑动速率明显低于南华—楚雄—建水断裂和无量山断裂;(2)红河断裂带的元江—元阳段、鹤庆—洱源段和小江断裂带北段处于强闭锁状态,南华—楚雄—建水断裂带和无量山断裂带中—北段的闭锁程度强于南段;(3)青藏高原东南缘南段现今地壳变形表现为近E-W向的拉张和近N-S向的挤压,最大剪切方向与Pms和XKS剪切波分裂的快波方向呈一定角度,表明地壳与地幔处于完全解耦状态,而中-下地壳低速层可能是壳幔解耦的主要原因之一;(4)青藏高原东南缘的整体变形受控于印度板块的推挤、印缅俯冲带的深源俯冲以及缅甸微板块与巽他板块的后撤/回退的共同作用. 相似文献
9.
龙门山断裂带南段地壳一维P波速度结构 总被引：2，自引：0，他引：2
基于2009年1月1日至2013年5月6日四川地震台网、重庆地震台网记录的龙门山断裂带南段587个地震的5 012个P波到时数据,利用最小一维速度模型方法反演了龙门山断裂带南段地壳一维P波速度模型及台站校正值,并将其应用到龙门山地区地震重定位中。结果表明,台站校正值表征出龙门山断裂带南段地表速度结构的横向不均匀性,青藏高原的彭灌杂岩体及宝兴杂岩体在近地表表现为高速异常,而四川盆地的第四纪沉积表现为低速异常。重定位后地震震源在北西向的剖面上呈明显的条带状并向北西倾斜,该地震带与宝兴杂岩下方的滑脱带延伸趋势一致。此外,该地震带上方分布着一条反冲地震带,两地震带呈"y"型分布,这可能是宝兴杂岩上方的岩层为调节逆冲过程受阻而产生的反冲运动所致。 相似文献
10.
利用区域固定台站和中国地震科学探测台阵记录的7349个近震事件的60471个Pg波绝对走时和196465个相对走时数据,采用双差地震层析成像获得滇西北地区(25°～28.2°N,99.5°～101.5°E)横向分辨率为0.2°的中、上地壳的三维P波速度模型,重点分析了区域内各主要断裂带及其邻区的速度结构特征.结果表明:金沙江—红河断裂带北段15 km以上的P波速度较低,重定位后中、小地震的震中主要位于低速异常的内部,且震源深度在断裂带两侧相似;推测金沙江—红河断裂带作为川滇菱形块体西南边界的剪切控制作用已弱化,分界能力局部减弱,并且断裂带下方主体的低速异常可能为跨越断裂的动力传递提供条件.丽江—小金河断裂带(西南段)两侧存在大范围的P波低速异常,推测此低速体可能是青藏高原东南向挤出的物质,而程海断裂带以东从近地表至25 km深处明显的P波高速异常体则可能会阻挡高原物质东南向的逃逸. 相似文献
11.
活动断裂带中地震时空分布的信息维 D1避免了容量维 D0的缺陷,考虑了每一地震事件对信息所作的贡献,从新的角度反映了地震分布时空结构特征.计算表明,炉霍大震前鲜水河断裂带地震分布时间结构信息维 D1=0.1051,这是该区大震活动的一个参考性判据.安宁河断裂带十七年现今地震分布时间结构信息维:北段,D1（tN）=0.1363;南段,D1（tS）=0.06710.地震空间分布信息维:北段,D1（KN）=1.053;南段,D1（Ks）=0.7758.南北两段分属信息维维数不同的两个自相似系统.南段地震活动自组织程度较高.这有助于强震重点监测区内主要危险段的判定地震时空分布 D1特征探索对于活断层研究以及地震预报都有一定的意义. 相似文献
12.
LI Xi RAN Yong-kang CHEN Li-chun WANG Hu YU Jiang ZHANG Yan-qi XIE Ying-qing 《地震地质》2016,38(3):596-604
Nine earthquakes with M≥6 have stricken the northern segment of the Red River fault zone since the historical records, including the 1652 Midu M7 earthquake and the 1925 Dali M7 earthquake. However, there have been no earthquake records of M≥6 on the middle and southern segments of the Red River Fault, since 886 AD. Is the Red River fault zone, as a boundary fault, a fault zone where there will be not big earthquake in the future or a seismogenic structure for large earthquake with long recurrence intervals?This problem puzzles the geologists for a long time. Through indoor careful interpretation of high resolution remote sensing images, and in combination with detailed field geological and geomorphic survey, we found a series of fault troughs along the section of Gasha-Yaojie on the southern segment of the Red River fault zone, the length of the Gasha-Yaojie section is over ten kilometers. At the same time, paleoseismic information and radiocarbon dating result analysis on the multiple trenches show that there exists geological evidence of seismic activity during the Holocene in the southern segment of the Red River fault zone. 相似文献
13.
Yebang Xu 《地震科学（英文版）》1992,5(2):389-398
The research of the information dimension (D 1) in an active fault zone considers the contribution of each seismic event to information and reflects the characteristics of the temporal and spatial distributions of earthquakes from a new point of view, avoiding some short-comings of the research about the capacity dimension (D 0). The results of calculation show that the information dimension of the temporal distribution in Xianshuihe active fault zone before Luhuo large earthquake isD 1=0.1051. It is a consult creterion of large earthquakes in future in the fault zone. The information dimensions of the temporal distribution of the earthquakes in Anninghe active fault zone are respectivelyD 1(t N)=0.1363 (for the north section) andD 1(t S)=0.06710 (for the south section). The information dimensions of the spatial distribution are respectivelyD 1(K N)=1.053 (for the north section) andD 1(K S)=0.7758 (for the south section). The north section and the south section belong to two self-similar systems with different information dimensions respectively. The extent of the self-organization of seismic activity in the south section is higher than that in the north section. This is helpful for us to judge the major dangerous section in the key region of the seismic monitoring. The research about the information dimension of the temporal and the spatial distributions of earthquakes is significant for the exploration of active fault zones and seismic prediction. 相似文献
14.
攀西地区位于峨眉山大火成岩省中西部,构造和岩浆特征显著,地震活动强烈.通过对野外重力测量得到的云县—会东和普洱—七甸两条剖面的高精度重力观测数据进行处理和分析,构建了沿剖面的二维地壳密度结构,其中普洱—七甸剖面与孟连—马龙宽角地震剖面部分位置重合.同时结合区域重力异常特征及下地壳视密度填图结果,得到如下初步认识:红河断裂带是南北地震带南段地区重要的构造分界线,断裂带南北向密度结构和莫霍面分布形态存在较大差异,沿走向构造变化.云县—会东剖面上大姚—会东段下地壳底部存在密度较高的壳幔过渡层,结合研究区下地壳底部壳幔过渡层的密度分布特征,认为该过渡层不是攀西裂谷下的"裂谷垫",而是由岩浆底侵作用造成的. 相似文献
15.
Yebang Xu 《地震学报(英文版)》1992,5(2):389-398
The research of the information dimension (D
1) in an active fault zone considers the contribution of each seismic event to information and reflects the characteristics
of the temporal and spatial distributions of earthquakes from a new point of view, avoiding some short-comings of the research
about the capacity dimension (D
0). The results of calculation show that the information dimension of the temporal distribution in Xianshuihe active fault
zone before Luhuo large earthquake isD
1=0.1051. It is a consult creterion of large earthquakes in future in the fault zone. The information dimensions of the temporal
distribution of the earthquakes in Anninghe active fault zone are respectivelyD
1(t
N)=0.1363 (for the north section) andD
1(t
S)=0.06710 (for the south section). The information dimensions of the spatial distribution are respectivelyD
1(K
N)=1.053 (for the north section) andD
1(K
S)=0.7758 (for the south section). The north section and the south section belong to two self-similar systems with different
information dimensions respectively. The extent of the self-organization of seismic activity in the south section is higher
than that in the north section. This is helpful for us to judge the major dangerous section in the key region of the seismic
monitoring. The research about the information dimension of the temporal and the spatial distributions of earthquakes is significant
for the exploration of active fault zones and seismic prediction.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 372–379, 1991.
This paper is sponsored by the Chinese Joint Seismological Science Foundation. The English version is improved by Zhenwen
An. 相似文献
16.
By using moving average method to separate Bouguer gravity anomaly field in Sichuan-Yunnan region, we got the low-frequency Bouguer gravity anomaly field which reflects the undulating of Moho interface. The initial model is obtained after seismic model transformation and elevation correction. Then, we used Parker method to invert the low-frequency Bouguer gravity anomaly field to obtain the depth of Moho interface and crustal thickness in the area. The results show that the Qinghai-Tibet block in the northwest of the study area deepens and thickens from the edge to the interior, with the depth of Moho interface and the crust thickness of about 52~62km and 54~66km, respectively. The depth of Moho interface in Sichuan Basin is about 38~42km. In Sichuan-Yunnan block, the depth of Moho interface is about 42~62km from southeast to northwest. Beneath the West Yunnan block, west of the Red River fault zone, the Moho depth is about 34~52km from south to north. The Longmen Mountains and Red River fault zone are the gradient zone of the Moho depth change. Along the Red River fault zone, the depth difference of Moho interface is increasing gradually from north to south. No obvious uplift is found on the Moho interface of Panzhihua rift valley. The depth of Moho interface distribution in Sichuan and Yunnan is obviously restricted by the collision between the Indian plate and the Eurasian plate and the lateral subduction of the Indo-China peninsula. The mean square error of the depth of Moho interface is less than 1.7km between the result of divisional density interface inversion and artificial seismic exploration. At the same time, we compared the integral with divisional inversion result. It shows that:in areas where there is obvious difference between the crust velocity and density structure in different tectonic blocks, the use of high resolution seismic exploration data as the constraints to the divisional density interface inversion can effectively improve the reliability of inversion results. 相似文献
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18.
Through simultaneous inversion of earthquake hypocenters and velocity structure, we obtained the precise locations of earthquakes occurring from 1981 to 2013 in northern Shanxi and the 3D velocity structure, and analyzed emphatically the Kouquan Fault. The result of earthquake relocation shows that earthquakes are concentrated in the central-north segment of Kouquan Fault and the distribution is sparse towards both south and north end of the fault, which indicates that the strong activity is in the central-north segment of Kouquan Fault and the seismicity becomes weaker towards both ends. The result of velocity structure shows that the earthquake concentrated segment of Kouquan Fault is on the side of relative low-velocity area in the high-velocity body, and the south segment of Kouquan Fault is the continuous low velocity. We can recognize the velocity gradient zone from the obvious depression near the Kouquan Fault, which, as we preliminarily speculate, may be the evidence of the presence of Kouquan Fault(or basement detachment)at the deep part. The parallel velocity profile (velocity ratio profile) to Kouquan Fault shows that the earthquake cluster in the central-north segment of Kouquan Fault is located in the abrupt change zone from high to low velocity(from high to low velocity ratio). 相似文献