滇西南地区澜沧断裂全新世滑动速率与走滑起始时间探讨

通过卫星影像解译、野外实地调查和地质填图,获得滇西南地区澜沧断裂的基本特征和活动性参数,澜沧断裂属于龙陵—澜沧新生地震断裂带的东南段,北起耿马县联合村,向南东经澜沧县哈卜吗、战马坡、大塘子至澜沧县城东南,总体走向NNW,长度约85km。该断裂为一条全新世活动的右旋走滑断裂,兼具倾滑分量,沿断裂形成了丰富的断错地貌现象,主要表现为断层陡崖、冲沟右旋、断层陡坎、断层沟槽、断层垭口和断陷凹坑等。通过详细的野外考察,选择典型断错地貌进行差分GPS测量,结合所获相应地貌面的年代数据,得到该断裂全新世以来平均右旋走滑速率为(4.2±2.3)mm/a,其结果与现今GPS观测所得速率相当,反映了该断裂长期以来滑动速率的稳定性。同时根据岩体的最大位错量4.6~4.8km,估算断裂开始右旋走滑的时代为距今约1.1 Ma,即早更新世晚期。     

利用滑动速率、古地震资料估算走滑断裂的粘滑及蠕滑量的方法

断层走滑包括粘滑和蠕滑,前者是伴有强震发生的快速运动,后者则是一种缓慢的无震稳滑运动。这２ 种运动常随时间交替出现,共同构成了断层的基本运动方式。在利用断层滑动速率讨论大震重复率的问题中,人们最关心的问题则是如何从总滑动量中分辨和划分出其中所包含的粘滑和蠕滑量,特别是对蠕滑量的划分,因为它直接影响着大震重复率的正确性。笔者在野外考察的基础上,对昌马活动断裂的位移量进行了分级,确定出昌马断裂带全新世以来的水平滑动量大致可划分为５个级别：３１～４１ ｍ ;２５～３１ ｍ ; １５～２２ ｍ ; ８～１３ ｍ ;１～５．５ ｍ ,同时依据古地震学方法并结合１４Ｃ断代法及断层崖形成年代的数学模拟计算,求得全新世以来在昌马断裂带上共发生５ 次古地震事件。在上述２ 项资料确定的基础上,进一步对昌马断裂带的粘滑及蠕滑量进行了划分,并给出了它们随时间的变化情况     

Experimental Study on the Stick-slip Phenomenon of Intact Granite under Solid Confining Pressure

In this paper,compression tests of intact granite samples have been made in a triaxial testing machine with solid confining pressure.From the tests,the influences of confining pressure and loading rate(axial strain rate)on the deformation and fracture process of rock samples,on the stress drop and recurrence interval of stick-slip events,and on the geometric distribution of the main fracture have been studied.The experimental results show that the loading rate influences the stress drop and recurrence interval of stick-slip events greatly.At lower loading rates,the stress drop of stick-slip events is greater,their recurrence interval is longer and shows no regularity in distribution.When the loading rate goes higher,the stress drop will become smaller and the recurrence interval will tend to be constant and stick-slip events show a quasi-periodicity.At lower confining pressures and strain rates,the main fracture may evolve into 2 X-shaped conjugate shear faults; whereas at higher confining pressures and     

On the interpretation of slow ground deformation precursory to the 1976 Friuli earthquake

During three years preceding the 1976 Friuli earthquake, a continuous southward ground tilt was recorded by a tiltmeter placed near Tolmezzo, 15 km north-west of the epicentre of the impending earthquake. The cumulative ground tilt amounted to as much as 3 minutes of arc. Since the tiltmeter was placed in the proximity of an active fault, such a tilt can be explained if the fault slipped aseismically on its shallower section during the same three year period. Aseismic slip on the fault might have been caused by the same mechanism which concentrated stress in the region and eventually produced the 1976 earthquake.     

慢滑移及相关脉动和慢地震研究的历史和现状

观测表明,慢滑移事件通常发生在活动断裂带内,为发震层之下的短暂滑移,能够造成地表的瞬态运动。与慢滑移密切相关的慢地震能够发射出频率在一定范围内的脉动信号,但不造成灾害性事件。慢滑移和慢地震很可能是断裂带上形变能释放的基本方式,其观测有可能为人们更深入地了解断裂带的动力学过程提供基础和依据。本文重点介绍近10年来关于慢地震和慢滑移事件的研究历史和现状。目前对慢滑移引发的地表形变和慢地震发射的脉动信号特征有了深入细致的研究,开展了对慢滑移的数值模拟和慢地震定位的研究;但对慢地震和慢滑移发生的位置、两者的关系以及物理机制等方面还存在很多争论和问题。     

东昆仑活动断裂带东段全新世滑动速率研究

文中通过对东昆仑活动断裂带托索湖至玛曲段的实际野外测量,获得了该段上的1组断裂位错实测数据和14C及TL测年样品。通过室内分析研究,发现大体以阿尼玛卿山玛积主峰为界,东昆仑活动断裂带托索湖至玛曲段可再分为花石峡段和玛沁段2个在几何上不连续的段落,花石峡段的全新世水平滑动速率(115±11)mm/a明显高于玛沁段(70±06)mm/a。此外,由于断裂而引起的断裂两侧的差异垂直隆升速率,花石峡段自4kaBP以来约为(21±03)mm/a,玛沁段自10kaBP以来约为055mm/a。这种差异垂直隆升速率的明显变化,一方面反映了东昆仑活动断裂带不同段落上活动的差异,另一方面也可能反映了研究区内全新世以来的快速隆升     

Determination of the direction and magnitude of recent tectonic stress in the Xianshuihe fault zone using fault slip data

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基于Landsat 8光学影像的巴基斯坦Awaran M_w7.7地震形变监测及参数反演研究

2013年9月24日巴基斯坦俾路支省(Balochistan)境内的阿瓦兰县(Awaran)发生了Mw7.7级地震.本文利用覆盖该地区的Landsat 8数据,基于影像配准的方法获取了该次地震的同震形变场,并运用地统计的方法对形变结果进行精度评定.针对传统四叉树算法中近场和远场中采样密度的不均匀性,以及噪音区域对数据降采样和反演结果收敛性的影响,本文提出了改进的四叉树算法对点的密度和形变梯度进行合理兼顾.最后利用光学影像获取的形变结果和数据的精度水平,基于Okada弹性半空间形变模型反演了该地震的震源参数和断层滑动分布.结果表明,地震断层北倾47°,滑动以左旋走滑为主,断层的西南部兼具少量的倾滑运动分量,断层滑动主要集中分布在断层面0~15km深度范围,最大滑动量达10m.反演获得的地震标量矩为4.68×1020 N·m,震级约为Mw7.75级.本文的研究结果可以为该地区的地壳应力变化研究和地震灾害评估提供依据,同时为Landsat 8光学影像应用于地震的形变研究提供参考.     

Dynamic Rupture in a 3-D Particle-based Simulation of a Rough Planar Fault

An appreciation of the physical mechanisms which cause observed seismicity complexity is fundamental to the understanding of the temporal behaviour of faults and single slip events. Numerical simulation of fault slip can provide insights into fault processes by allowing exploration of parameter spaces which influence microscopic and macroscopic physics of processes which may lead towards an answer to those questions. Particle-based models such as the Lattice Solid Model have been used previously for the simulation of stick-slip dynamics of faults, although mainly in two dimensions. Recent increases in the power of computers and the ability to use the power of parallel computer systems have made it possible to extend particle-based fault simulations to three dimensions. In this paper a particle-based numerical model of a rough planar fault embedded between two elastic blocks in three dimensions is presented. A very simple friction law without any rate dependency and no spatial heterogeneity in the intrinsic coefficient of friction is used in the model. To simulate earthquake dynamics the model is sheared in a direction parallel to the fault plane with a constant velocity at the driving edges. Spontaneous slip occurs on the fault when the shear stress is large enough to overcome the frictional forces on the fault. Slip events with a wide range of event sizes are observed. Investigation of the temporal evolution and spatial distribution of slip during each event shows a high degree of variability between the events. In some of the larger events highly complex slip patterns are observed.     

求解活断层滑动速率的分形方法及其初步应用

断层平均滑动速率是描述和衡量断层活动强度的一个重要指标。破裂过程的分形结构决定了断层能量结构和几何结构都存在自相似性,断层系的尺度无关性对于断层活动性的定量化研究有着重要的理论价值和实用价值。本文以破裂发展的分形理论为基础,发展了求解活断层现代滑动速率的分形方法,导出了一个便于应用的分形公式。并以川西鲜水河断裂带为例对其中的活动断层的现代滑动速率作了计算,结果表明分形方法是研究断层活动强度的有效捷径。     

1932年昌马地震破裂错动过程的初步探讨

以1932年12月25日发生在甘肃省境内祁连山西部的昌马地震(Ms=7.5)造成的宏观地表破裂带的调查与分析为基础,结合有关断裂活动的资料与室内模拟实验结果,本文着重探讨昌马地震发震断裂的构造演化及其应力集中部位的破裂错动过程。从宏观的角度提出了多破裂错动起始点的昌马地震断层模式     

断裂微观滑移方式标志在地震安全性评价中的应用

将笔者近年来总结归纳出的活动断裂滑动特性民引入重大工程场地地震安全性评价工作中，结合样品的产出环境及宏观和超微观滑移特性标志分析，对样品所反映的最新活动方式进行鉴定，并在实践中补充和完善识别标志，从而为工程场地地震环境分析提供微观依据。     

倾斜断层深部不均匀滑动的反演计算

根据倾斜断层走滑、倾滑及拉张运动产生的地表位移计算公式，利用Ｈａｒｒｉｓ和Ｓｅｇａｌｌ的反演方法，建立了倾斜断层具多个滑动分量的反演模型，编制了相应的计算机程序，实现了利用大地测量资料反演计算不同产状断层深部不同运动方向的滑动速率或滑动量。并以北京地区两条主要活动断层为例进行了计算，获得结果与北京地区区域应力场及断层应力场具有较好的一致性     

Late Quaternary Activity of the Chuxiong-Nanhua Fault and the 1680 Chuxiong MS6 ¾ Earthquake

In this paper, according to the results of the satellite imagery interpretation and field investigation, we study the active features and the latest active times of the Chuxiong-Nanhua fault, the Quaternary basins formation mechanism, and the relationship between the fault and the 1680 Chuxiong M_S6 ¾ earthquake. Several Quaternary profiles at Lvhe, Nanhua reveal that the fault has offset the late Pleistocene deposits of the T2 and T3 terraces of Longchuan river, indicating that the fault was obviously active in late Quaternary. The Chuxiong-Nanhua fault has been dominated by dextral strike slip motion in the late Quaternary, with an average rate of 1.6-2.0mm/a. Several pull apart Quaternary basins of Chuxiong, Nanhua, and Ziwu etc. have developed along the fault. The 1680 Chuxiong M_S6 ¾ earthquake and several moderate earthquakes have occurred near the fault. The Chuxiong-Nanhua fault are the seismogenic structure of those earthquakes, the latest fault movement was in the late-Pleistocene, and even the Holocene. In large area, the Chuxiong-Nanhua fault and the eastern Qujiang fault and the Shiping fault composed a set of NW-trending oblique orientation active faults, and the motion characteristics are all mainly dextral strike slip. The motion characteristics, like the red river fault of the Sichuan-Yunnan Rhombic Block southwestern boundary, are concerned with the escaping movement of the Sichuan-Yunnan Rhombic Block.     

龙陵-瑞丽断裂(南支)北段晚第四纪活动性特征

遥感影像解译和野外地质地貌调查表明,龙陵-瑞丽断裂(南支)北段是以左旋走滑为主兼张性正断的区域性活动断裂。根据一些断错地貌点的大比例尺填图、实地测量及其年代学分析,确定了该断裂为全新世活动断裂,断裂晚更新世以来的平均水平滑动速率为2.2mm/a,平均垂直滑动速率为0.6mm/a;全新世以来的平均水平滑动速率为1.8～3.0mm/a,平均垂直滑动速率为0.5mm/a。断裂晚更新世以来的滑动速率在不同的时间尺度上变化不大,反映了该断裂晚更新世以来的活动强度比较平稳     

郯庐断裂带（莒县招贤～宿迁晓店段）变形产物中的微观粘滑与蠕滑标志

通过对郯庐断裂带莒县招贤～宿迁晓店段断裂变形产物进行定向采集、原态固结，对其进行显微观测，结合宏观和实验岩石学资料分析，归纳出反映该活动断裂段运动特性的微观粘滑与蠕滑标志，并对有关问题进行了讨论     

祁连山北缘玉门-北大河断裂晚第四纪活动特征

通过卫星影像解译、野外实地调查并结合前人研究成果,对位于祁连山北缘的玉门—北大河断裂晚第四纪构造活动特征进行研究。结果表明,玉门—北大河断裂为一条全新世活动的逆冲断裂,该断裂西起玉门青草湾,向东经老玉门市、大红泉止于骨头泉,全长约80km,整体走向NWW。根据断裂的几何结构及活动习性可将其分为三段:东段构造形态简单连续,为逆冲断层陡坎为主的古地震地表破裂带;中段结构复杂,由多条次级断层组成,以逆冲扩展为主;西段未出露地表而成为盲断裂-褶皱带。通过对断层陡坎差分GPS测量及相应地貌面年代测试,得到断裂晚更新世以来逆冲速率约为(0.73±0.09)mm/a。     

兰州马衔山北缘断裂带的新活动特征

通过详细地质填图研究获得了兰州马衔山北缘断裂带的几何学、新活动性、断错微地貌及滑动速率等的定量资料。马衔山北缘断裂为一条历史悠久的区域性活动断裂 ,其几何形态较简单 ,总体走向N6 0°W ,全长约 115 .5km。根据断裂分叉、拐弯及不连续阶区等几何特征和活动性的差异 ,大致可以将该断裂划分为 4条次级断层段 ,自东向西分别称为内官营段、马衔山段、七道梁段和雾宿山段。断裂的新活动具分段性 ,其中的内官营段为具逆断特性的晚更新世活动段 ,而马衔山段、七道梁段和雾宿山段均为全新世活动段。该断裂早期具逆断特性 ,大约自中更新世以来以左旋走滑为主兼具倾滑运动分量 ,形成了一系列山脊、冲沟、阶地等的左旋断错 ,断距几米至几百米。沿断裂带的水平位移具分组现象 ,可能反映了断裂的黏滑活动特性。根据Ⅰ ,Ⅱ级阶地的左旋断错值及其年代 ,得到了马衔山北缘断裂带晚更新世以来的平均水平滑动速率约为 3.73mm/a。同时沿断裂带还保存有断崖和断坎等 ,其中Ⅰ级阶地上的断坎高 1～ 1.5m左右     

COSMOGENIC NUCLIDES EXPOSURE DATING FOR BEDROCK FAULT SCARP: RECONSTRUCTING THE PALEOEARTHQUAKE SEQUENCE

The bedrock scarps are believed to have recorded the continuous information on displacement accumulation and sequence of large earthquakes. The occurrence timing of large earthquakes is believed to be correlated positively with the exposure duration of bedrock fault surfaces. Accordingly, cosmogenic nuclides concentration determined for the bedrock footwall can offer their times, ages, and slip over long time. In general, multiple sites of fault scarps along one or even more faults are selected to carry out cosmogenic nuclide dating in an attempt to derive the temporal and spatial pattern of fault activity. This may contribute to explore whether earthquake occurrence exhibits any regularity and predict the timing and magnitude of strong earthquakes in the near future. Cosmogenic nuclide ³⁶ Cl dating is widely applied to fault scarp of limestone, and the height of fault scarp can reach as high as 15~20m. It is strongly suggested to make sure the bedrock scarp is exhumed by large earthquake events instead of geomorphic processes, based on field observation, and data acquired by terrestrial LiDAR and ground penetration radar (GPR). In addition, it is better for the fault surface to be straight and fresh with striations indicating recent fault movement. A series of bedrock samples are collected from the footwall in parallel to the direction of fault movement both above and below the colluvium, and each of them is~15cm long,~10cm wide, and~3cm thick. The concentrations of both cosmogenic nuclide ³⁶ Cl and REE-Y determined from these samples vary with the heights in parallel to fault scarps. Accordingly, we identify the times of past large earthquakes, model the profile of ³⁶ Cl concentration to seek the most realistic one, and determine the ages and slip of each earthquake event with the errors. In general, the errors for the numbers, ages, and slips of past earthquake events are ±1-2, no more than ±0.5-1.0ka, and ±0.25m, respectively.     

走滑断裂带中挤压阶区内部剪切构造初探

野外地质调查和航片立体镜下解译发现,小江断裂带北段蒙姑和东支大营盘两个挤压阶区内部发育有剪切构造,它们在地表主要表现为断裂槽地、断层陡坎、地裂缝等。挤压阶区内部剪切构造和拉张阶区内部剪切构造一样,是阶区形成后,随着走滑断裂的进一步活动而形成的新生性构造