历史的烙印 永久的反思--纪念1303年山西洪洞大地震700周年

2003年9月17日是我国史载的第一个8级地震700周年纪念日,这是一个值得纪念的日子。元大德七年八月初六,公历1303年9月17日,山西省洪洞赵城发生强烈地震。史料记载“民居官舍荡然无存”,建筑物破坏惨重;“山摧阜移,其土之奋怒奔突数里,跨涧鄄谷”“郇堡徙十余里”,山川地貌为之改观;“死亡20万有余”,人口伤亡巨大。震撼之烈、破坏之重、伤亡之大、波及之广当属其震。根据烈度震级关系测算,强度为8级。洪洞至今尚存有这次地震的遗迹,遍散于山西各处的碑刻题记,对当时震害的描述历历在目。抚今追昔,震后思震,洪洞地震的烙印值得反思。洪洞…     

河北省阳原六棱山北麓断裂古地震年代学的初步研究

六棱山北麓断裂位于阳原盆地南缘，是一条总体走向北东东，倾向北北西的倾滑正断裂。它的断错地貌在河北阳原独山堡发育最好且保存完整在，在狡山堡六棱山北麓断层陡坎前缘开挖了２个探槽，共揭示了２次古地震事件；采集了多个测年样品，经红外释光（ＩＲＳＬ）测年技术测定，初步获得了２次古地震事件发生的可能时代。     

汶川M_S8.0地震发震断裂大地震原地重复现象初析

在历史记录中,成都和龙门山地区没有发生过类似汶川MS8.0地震强度的地震。那么,在地质记录中是否会存在类似震级的古地震遗迹?作者分别在中央和前山断裂中段的地表破裂带上4个地点开挖了探槽4个和剖面1个,并进行了断错地貌面的实测。文中从几个地点新老地貌面累计变形量、探槽揭露的古地震遗迹等方面讨论汶川地震发震断裂大地震原地重复现象存在的基本事实。结果表明:无论在中央断裂的小鱼洞、擂鼓镇还是前山断裂的白鹿镇、汉旺等地,汶川5.12地震之后Ⅱ级阶地断层陡坎与Ⅰ级阶地陡坎高度基本呈倍数关系,探槽揭露Ⅱ级阶地标志地层(黄砂土层)在断裂两盘的位差也是5.12地震的约2倍,显示在龙门山地区区域Ⅱ级阶地形成之后,汶川5.12地震发生之前,存在一次与汶川MS8.0地震地表变形规模相当的地震事件     

西昌市大箐梁子一带古地震初探

大箐梁子一带有着众多明显的古地震遗迹。它们的相互叠加和重复，说明该地是一个曾多次发生强震的震中区。从古地震遗迹的初步研究可知，目前地处大箐梁子北侧一带的活动断层侵蚀作用十分活跃，造成了邛海水系袭夺则木河上游水系，并迫使分水岭不断南移。     

山西全新世古地震的基本特征

本文系统地总结了山西省境内多年来发现的全新世古地震的基本特征，并将其分为七大类和若干种。文章对每种古地震遗迹的基本特征进行了描述。     

山西侯马—河津一带西汉初期的强烈地震

1989年至1987年间,在国家地震局招标合同项目《全新世古地震的研究方法和确定标志》工作中,笔者在山西省侯马至河津一带,发现了大规模地震断层和许多古地震遗迹。本文就是在此基础上,对黄土中的古地震遗迹进行了总结,分析研究了古地震的分布和特征,讨论了侯马至河津一带西汉初期强震的规模和震中。     

福建深沪湾海底古森林与全新世强古地震

介绍了深沪湾海底古森林遗迹，指出了海底古森林与古地震的关系，给出了深沪湾全新世强古地震的依据。     

青海省温泉水库近场区活动断裂特征

在全面收集和总结前人工作资料的基础上，采用野外地震地质学研究方法，结合浅层地震勘探、断层气测量、开挖探槽、年代测样等丰富的第一手资料，综合分析总结了青海省格尔木市温泉水库近场区内活动断裂的特征及其古地震形变遗迹。特别是对穿越坝体的京昆仑活动断裂进行了更为详细的研究，总结出它是全新世以来经过多期强烈活动，水平位移达40～80m，平滑速率为7．5～9．5mm／a，是古地震遗迹十分状观的一条岩石围深大断裂。     

1668年郯城8.5级地震断裂的全新世滑动速率、古地震和强震复发周期

本文根据野外考察，实测和开挖资料研究了１６６８年郯城８ １／２级地震断裂上的全新世位移分布，滑动速率，古地震遗迹，古地震期次和强震复发周期以及地震破裂模式。     

1668年郯城8.5级地震断裂的全新世滑动速率,古地震和强震复发周期

本文根据野外察、实例和开挖资料，研究了１６６８年郯城８．５级地震断裂的水年和垂直位移及地震标志和证据、全新世位移分布和滑动速率、古地震遗迹、古地震期次、强震复发周期以及地震破裂模式。     

从新史料看元大德七年山西洪洞大地震

在前人研究的基础上,根据新发现的史料,对元大德七年(公元1303年)洪洞大地震的破坏范围、震亡人数、震中、大型地体滑移、“李忠孝感碑”的下落及地震造成水利设施的破坏等情况进行了进一步的讨论,提出了新的见解。     

山西破坏性地震的人员伤亡和地面破坏特征

山西是一个多地震的地区，有史料记载以来共发生81次破坏性地震，这些地震除了在地震区引起人员伤亡和建筑物破坏以外，还引起喷沙冒水、地裂地陷、滑坡和崩塌等地面破坏。根据山西地震造成的人员伤亡和地面破坏的资料，讨论分析了人员伤亡和地面破坏的分布特点以及与震级的关系，这些结果对地震灾害的预测预防很有意义。     

岷县漳县6.6级地震典型滑坡特征及其诱发机制

地震和降雨是滑坡产生的两大诱因。一般认为二者的耦合作用概率小,在现实中也较少发现有此种实例。岷县漳县6.6级地震中黄土地震滑坡广泛发生,本文通过现场调查,在相关降雨量数据、航空影像空间分析的基础上研究了两个地点(永光村滑坡和堡子村滑坡)的典型地震黄土滑坡的空间展布特征和发生、发展过程,分析了诱发机制。结果发现:(1)地震滑坡呈带状分布与地震发震构造走向一致;(2)位于极震区范围的永光村黄土滑坡具有泥流特征,土体含水量可达塑限以上,是由于过量降水和强地震动耦合作用下发生;(3)堡子村黄土地震滑坡则主要为强地震动所诱发,滑距较短,并具滞后发生特性。本结果对未来地震中滑坡的预防与防治具有借鉴意义。     

Seismically reactivated Hattian slide in Kashmir, Northern Pakistan

The Pakistan 2005 earthquake, of magnitude 7.6, caused severe damage on landscape and infrastructure, in addition to numerous casualties. The event reactivated Hattian Slide, creating a rock avalanche in a location where earlier mass movements had happened already, as indicated by satellite imagery and ground investigation. The slide originated on Dana Hill, in the upper catchment area of Hattian on Karli Stream, a tributary of Jhelum River, Pakistan, and buried the hamlet Dandbeh and several farms nearby. A natural dam accumulated, impounding two lakes, the larger one threatening parts of downstream Hattian Village with flooding. An access road and artificial spillways needed to be constructed in very short time to minimize the flooding risk. As shown by this example, when pointing out the risk of large-scale damage to population and infrastructure by way of hazard indication maps of seismically active regions, and preparing for alleviation of that risk, it is advisable to consider the complete Holocene history of the slopes involved.     

A comparative study of bridge damage due to the Wenchuan, Northridge, Loma Prieta and San Fernando earthquakes

A comparative study of selected bridge damage due to the Wenchuan, Northridge, Loma Prieta and San Fernando earthquakes is described in this paper. Typical ground motion effects considered include large ground fault displacement, liquefaction, landslide, and strong ground shaking. Issues related to falling spans, inadequate detailing for structural ductility and complex bridge configurations are discussed within the context of the recent seismic design codes of China and the US. A significant lesson learned from the Great Wenchuan earthquake, far beyond the opportunities to improve the seismic design provisions for bridges, is articulated.     

Discrete Element Modeling of Tangjiagou Two-Branch Rock Avalanche Triggered by the 2013 Lushan MW6.6 Earthquake, China

Two branches of Tangjiagou rock avalanche were triggered by Lushan earthquake in Sichuan Province, China on April 20^th, 2013. The rock avalanche has transported about 1 500 000 m³ of sandstone from the source area. Based on discrete element modeling, this study simulates the deformation, failure and movement process of the rock avalanche. Under seismic loading, the mechanism and process of deformation, failure, and runout of the two branches are similar. In detail, the stress concentration occur firstly on the top of the mountain ridge, and accordingly, the tensile deformation appears. With the increase of seismic loading, the strain concentration zone extends in the forward and backward directions along the slipping surface, forming a locking segment. As a result, the slipping surface penetrates and the slide mass begin to slide down with high speed. Finally, the avalanche accumulates in the downstream and forms a small barrier lake. Modeling shows that a number of rocks on the surface exhibit patterns of horizontal throwing and vertical jumping under strong ground shaking. We suggest that the movement of the rock avalanche is a complicated process with multiple stages, including formation of the two branches, high-speed sliding, transformation into debris flows, further movement and collision, accumulation, and the final steady state. Topographic amplification effects are also revealed based on acceleration and velocity of special monitoring points. The horizontal and vertical runout distances of the surface materials are much greater than those of the internal materials. Besides, the sliding duration is also longer than that of the internal rock mass.     

Slide roof system for dynamic response reduction

A slide roof system (SRS) is proposed to reduce the dynamic response of buildings to earthquake excitations. A SRS consists of a roof structure, springs and friction materials, providing mass, stiffness and damping, respectively. The method of optimization of stiffness and friction coefficient for the SRS is introduced. A numerical analysis of an eight‐story frame structure subjected to ground motions and shaking table tests of a five‐story frame was carried out to study the effectiveness of the SRS. The results show that the SRS can reduce the maximum dynamic response as much as 60–70% in the first resonate band and 35–50% in the second resonate band. Copyright © 2007 John Wiley & Sons, Ltd.     

2010年墨西哥Baja Mw7.2地震与中国玉树Mw6.9地震强地震动特征的对比研究

2010年4月4日墨西哥Baja地区发生Mw7.2地震,2人遇难;同年4月14日中国青海省南部玉树地区发生Mw6.9地震,截至2010年4月25日,已造成2220人遇难.有报道指出,玉树地震矩震级小于Baja地震,人员伤亡却远大于后者,主要原因在于玉树地区抗震设防标准低、建筑物抗震性能差.地震造成破坏程度的大小并非仅仅...     

Seismic response analysis of multidrum classical columns

This paper presents a numerical investigation on the seismic response of multidrum classical columns. The motivation for this study originates from the need to understand: (a) the level of ground shaking that classical multidrum columns can survive, and (b) the possible advantages or disadvantages of retrofitting multidrum columns with metallic shear links that replace the wooden poles that were installed in ancient times. The numerical study presented in this paper is conducted with the commercially available software Working Model 2D?, which can capture with fidelity the sliding, rocking, and slide‐rocking response of rigid‐body assemblies. This paper validates the software Working Model by comparing selected computed responses with scarce analytical solutions and the results from in‐house numerical codes initially developed at the University of California, Berkeley, to study the seismic response of electrical transformers and heavy laboratory equipment. The study reveals that relative sliding between drums happens even when the g‐value of the ground acceleration is less than the coefficient of friction, µ, of the sliding interfaces and concludes that: (a) typical multidrum classical columns can survive the ground shaking from strong ground motions recorded near the causative faults of earthquakes with magnitudes M_w=6.0–7.4; (b) in most cases multidrum classical columns free to dislocate at the drum interfaces exhibit more controlled seismic response than the monolithic columns with same size and slenderness; (c) the shear strength of the wooden poles has a marginal effect on the sliding response of the drums; and (d) stiff metallic shear links in‐between column drums may have an undesirable role on the seismic stability of classical columns and should be avoided. Copyright © 2005 John Wiley & Sons, Ltd.     

The Northridge, California, earthquake of 1994: fire ignition by strong shaking

The Northridge earthquake contributed unprecedented detail and quality of data on strong ground motion and on its effects on man-made structures. About 110 fires have been attributed directly to the effects of this earthquake. Two hypotheses for the principal causative agents leading to fire ignition were examined: differential motion and strains in the soil, and inertial forces. The fire-ignition frequency is described with respect to: (1) simple measures of strain in the soil (via density of water pipe breaks, n), (2) occurrence of severely damaged buildings (via density of red-tagged buildings, N), (3) site intensity of shaking, (I_MM), and (4) inertial forces (via peak horizontal ground velocity, v_m). It is shown that the rate of fires (per unit area) ignited by earthquake shaking can be predicted by several empirical equations of comparable accuracy and in terms of common scaling parameters of strong ground motion.