Analyses of Seismic Deformation at the Kibyra Roman Stadium,Southwest Turkey

The ancient city of Kibyra in southwest Turkey has the potential to reveal the location and date of historical earthquakes. The most compelling evidence for earthquake faulting is observed in the city's Roman stadium. Damage related to seismic shaking is characterized by systematically collapsed columns, dilated and collapsed walls, and by rotated and displaced blocks in the stadium. Detailed archaeoseismological observations suggest that Kibyra was affected by earthquakes that were also recorded in historical earthquake catalogs. Although there is no historical record of a large earthquake after the 5th century A.D., Optically stimulated luminescence (OSL) dating of deposits under the collapsed blocks suggests a later seismic event. OSL results indicate that another large event occurred in southwest Turkey, probably around the 10–11th century A.D., and caused extensive damage (I_o = VIII‐IX) to the Kibyra stadium.     

Archaeoseismological investigation of the ancient Ayla site in the city of Aqaba,Jordan

Many tens of severe earthquake damage patterns were revealed at the ancient city of Ayla. The seismic deformation patterns are of various types, including systematic tilting of walls, systematic shifting and rotation of wall fragments and individual stones, arch deformations and joints crossing two or more stones. Features of later repair, supporting walls and secondary use of building stones suggest that the damage patterns can be explained by two historical devastating earthquakes: (I) revealed in the constructions built during the late Rashidun period (644–656 A.D.); (II) revealed in the structures restored and/or built during the Fatimid period (1050–1116 A.D.). The maximum observed intensity of both earthquakes at the studied site was not less than IX (EMS98 scale). The sources of the seismic events were probably the Dead Sea Transform and Wadi Araba Faults that cross the site obliquely. The last 1995 Nuweiba earthquake with maximum observed intensity VIII has also left its clear traces in the excavated ancient Ayla buildings. The severity of the destruction was significantly increased because of site effects.     

Structural damages of the May 19, 2011, Kütahya–Simav earthquake in Turkey

Reconnaissance observations are presented on the building damage caused by the May 19, 2011, Kütahya–Simav earthquake in Western Turkey as well as an overview of strong ground motion data recorded during the earthquake is given. According to Disaster and Emergency Management Presidency of Turkey, the magnitude of the earthquake is 5.7 in local magnitude scale. Although the earthquake can be regarded as a moderate event when considering its magnitude and strong motion recordings, it caused excessive structural damage to buildings in Simav district and several villages in the near vicinity. During the field investigation, different types of structural damage were observed mainly in the reinforced concrete frame buildings with infill walls and masonry buildings with various types of construction materials. Observed damage resulted from several deficiencies in structural and non-structural components of the buildings. Poor construction materials and workmanship, non-conforming earthquake-resistant design and construction techniques and non-ductile detailing are the main reasons for such an extensive damage, as observed in many past earthquakes in Turkey.     

The geotechnical effects of long human habitation (2000< years): Earthquake induced landslide hazard in the city of Zefat, northern Israel

This work studies the effects of long human habitation on site geotechnical conditions. It is focused on the city of Zefat that is located on the borders of the Dead Sea Transform in northern Israel. The city of Zefat, suffered severe damage and loss of life in historical earthquakes, as a consequence of earthquake induced landslides (EILS). In this work we evaluate the current EILS hazard for the city of Zefat using a GIS-based regional Newmark analysis, with calibration of the calculated Newmark displacement (representing EILS hazard) using maps of field evidence and historical documents testifying to slope instability that occurred in historical earthquakes.

We found that the core city of Zefat is built on a layered anthropogenic material, few meters deep which, was deposited as a result of more than 2000 years of human habitation. The anthropogenic material is mechanically weak, susceptible to slope failure and to amplification of seismic-shaking. It is responsible for the city's devastation in historical earthquakes and it is the source for the current high seismic hazard as well.

Our model shows that earthquakes of magnitudes (M_w) 5, 6 and 7 at distances of up to 10 km, 50 km and more than 100 km, respectively, are likely to induce landslides in the core city of Zefat. The current engineering status of the city is poor, and as a consequence severe damage and loss of life are expected in future earthquakes due to EILS, unless major engineering efforts are made. Cities in the Eastern Mediterranean with comparable long habitation histories (e.g., Jerusalem, Tiberias, Nablus, Amman) are expected to have similar geotechnical problems in their old sections and are advised to take appropriate engineering steps to reduce damage and loss of life in future earthquakes.

Evaluation of historical earthquake magnitudes based on reported local-damage may, however, lead to overestimated magnitudes where the damaged sites are built on anthropogenic talus (a common setting in the vicinity of the Dead Sea Transform).     

Response and Stability of Underground Structures in Rock Mass during Earthquakes

Underground structures are well known to be earthquake resistant. However, the recent earthquakes showed that underground structures are also vulnerable to seismic damage. There may be several reasons such as high ground motions and permanent ground movements. This study attempts to describe various forms of damage to underground structures such as tunnels, caverns, natural caves and abandoned mines during major earthquakes. Results of various model tests on shaking table are also presented to show the effect of ground shaking on the response and collapse of underground structures in continuum and discontinuum. Furthermore, some empirical equations are proposed to assess the damage to underground structures, which may be useful for quick assessments of possible damage.     

Archaeological evidence for destructive earthquakes in Sicily between 400 B.C. and A.D. 600

A systematic archaeoseismological study indicates that at least three earthquakes occurred between 400 B.C. and A.D. 600, causing destruction to numerous ancient monuments in Sicily. Evidence for these earthquakes comes from the collapse style of buildings (toppled walls, column drums in a domino‐style arrangement, directional collapses, etc.), and the exclusion of other likely causes for such effects. Dating of inferred earthquakes is based on coins (accurate to within 5–10 years), pottery (accurate to within 50–200 years), and other artifacts. The oldest documented earthquake occurred between 370 and 300 B.C. and caused the collapse of two Greek temples in Selinunte. This otherwise poorly documented event was probably also the cause of extensive destruction in northeastern Sicily in the first century A.D. Destruction of some sites may be assigned to an earthquake that occurred between 360 and 374 and correlates with the A.D. 365 seismic sequence known from historical sources. This study covers a wider region and provides a more precise dating of earthquakes than previous studies. Although it focuses on a certain period (4th–3rd centuries B.C., 4th–7th centuries A.D.), it indicates that the period before A.D. 1000 is not a period of seismic quiescence in Sicily as was previously believed, but to a period characterized by strong and destructive earthquakes. © 2009 Wiley Periodicals, Inc.     

Archaeoseismological evidence of past earthquakes in Rome (fifth to ninth century A.D.) used to quantify dating uncertainties and coseismic damage

The transformation of Rome during the Late Antiquity and the Early Middle Ages has been investigated by archaeologists and historians. Social and political changes are the main aspects which led to a progressive modification of the urban framework; abandonment, spoliation and transformation of buildings are quite diffused as documented by the archaeological literature. The consequence of these practices is a higher vulnerability of the buildings which, from the seismological point of view, played a main role in increasing the effects of seismic shaking. A number of earthquakes have struck Rome during the period of investigation (fifth to ninth century A.D.), known from historical sources: 443, 484–508, 618, 801, 847; in some cases (443, 484–508, 801) damage has been documented. In contrast, the archaeological sources characterise collapse layers and evidence of destruction at different sites with changing and not always conclusive chronological constraints. Consequently, collapse and destruction have been alternatively attributed to the above-mentioned earthquakes. Through a geoarchaeological and stratigraphic analysis of potentially coseismic collapse units, we want (1) to describe the archaeoseismic evidence derived from recent excavations and from the available literature (e.g. Piazza Madonna di Loreto, Piazza Venezia, Palazzo Valentini Crypta Balbi, Colosseo, Basilica Hilariana, Basilica di Santa Petronilla, Santa Maria Antiqua,…); (2) to discuss the chronological problems and the uncertainty of attribution of the collapse units to known historical earthquakes; (3) to discuss the earthquake damage exaggeration due to erroneous attribution of seismic origin to the evidence of destruction derived from archaeological data. Finally, we will infer the role that earthquakes may have had on the development of the urban landscape in the fifth to ninth century A.D.     

Centrifuge modelling-based verification of response spectra design methods for some vulnerable structures

Residential RC framed structures suffered heavily during the 2001 Bhuj earthquake in Gujarat, India. These types of structures also saw severe damage in other earthquakes such as the 1999 Kocaeli earthquake in Turkey and 921 Ji-Ji earthquake in Taiwan. In this paper the seismic response of residential structures was investigated using physical modelling. Idealised soft storey and top heavy, two degrees of freedom (2DOF) portal frame structures were developed and tested on saturated and dry sand models at 25 g using the Schofield Centre 10-m Beam Centrifuge. It was possible to recreate observed field behaviour using these models. As observed in many of the recent earthquakes, soft storey structures were found to be particularly vulnerable to seismic loads. Elastic response spectra methods are often used in the design of simple portal frame structures. The seismic risk of these structures can be significantly increased due to modifications such as removal of a column or addition of heavy water tanks on the roof. The experimental data from the dynamic centrifuge tests on such soft storey or top-heavy models was used to evaluate the predictions obtained from the response spectra. Response spectra were able to predict seismic response during small to moderate intensity earthquakes, but became inaccurate during strong earthquakes and when soil structure interaction effects became important. Re-evaluation of seismic risk of such modified structures is required and time domain analyses suggested by building codes such as IBC, UBC or NEHRP may be more appropriate.     

中国活动构造与地震活动

文中研究了中国活动构造与地震活动的关系 ,包括活动断裂、活动褶皱、活动盆地和活动块体与地震活动的关系。全部 8级、绝大部分 7～ 7.9级地震均发生在活动块体边界活动构造带内 ;但对内部有次级活动构造的块体而言 ,少数 7～ 7.9级地震和部分 6～ 6 .9级地震也可能发生在块体内部的活动构造带上。大地震与活动断裂、活动褶皱和活动盆地的关系十分紧密 ,70多次 7级以上地震的同震破裂带及其位移参数与活动构造完全一致 ,7～ 8级地震均发生在活动断裂、活动褶皱和活动盆地带内 ,仅个别地震由于发生在高原和高山区 ,情况不明 ,6～ 6 .9级地震则大约有 5 %～ 15 %发生在活动构造带外或者情况不明。由于中国各断块区应力环境的差别 ,各区活动构造变形和地震发震构造类型也有所不同 ,文中对不同构造区走滑型 ,逆断裂褶皱型和正断裂拉张型活动构造和地震发震构造模型作了讨论。     

The Role of Earthquake-Related Effects in Urban Complexes

A number of cases where earthquake-induced damage was massive or presented interesting distribution patterns in recent earthquakes are presented.The highly serious damage along reactivated seismic faults and fractures is discussedfor the earthquakes of Pyrgos (Greece), Egio (Greece) and Kobe (Japan). Additionally, we describe characteristic types of building failure in the earthquake of Egio,caused by the coexistence of surficial faulting and liquefaction. Of particularinterest is the damage pattern in the Kobe and Dinar earthquakes, attributed to seismicwave directivity, caused by migration of the earthquake source. Finally, a specialcase of building damage is described for the case of the Adana, Turkey earthquake,which is connected to the shape and the azimuthal location of buildings in respectto the epicentre. All the above cases are valuable sources of information and can be utilizedin the reduction of seismic risk in constructions and urban complexes.     

Experimental vulnerability curves for the residential buildings of Iran

Iran is one of the most seismically active countries of the world located on the Alpine-Himalayan earthquake belt. More than 180,000 people were killed due to earthquakes in Iran during the last five decades. Considering the fact that most Iranians live in masonry and non-engineered houses, having a comprehensive program for decreasing the vulnerability of society holds considerable importance. For this reason, loss estimation should be done before an earthquake strikes to prepare proper information for designing and selection of emergency plans and the retrofitting strategies prior to occurrence of earthquake. The loss estimation process consists of two principal steps of hazard analysis and vulnerability assessment. After identifying the earthquake hazard, the first step is to evaluate the vulnerability of residential buildings and lifelines and also the social and economic impacts of the earthquake scenarios. Among these, residential buildings have specific importance, because their destruction will disturb the daily life and result in casualties. Consequently, the vulnerability assessment of the buildings in Iran is important to identify the weak points in the built environment structure. The aim of this research is to prepare vulnerability curves for the residential buildings of Iran to provide a proper base for estimating probable damage features by future earthquakes. The estimation may contribute fundamentally for better seismic performance of Iranian societies. After a brief review of the vulnerability assessment methods in Iran and other countries, through the use of the European Macroseismic method, a model for evaluating the vulnerability of the Iranian buildings is proposed. This method allows the vulnerability assessment for numerous sets of buildings by defining the vulnerability curves for each building type based on the damage observations of previous earthquakes. For defining the vulnerability curves, a building typology classification is presented in this article, which is representative of Iranian building characteristics. The hazard is described in terms of the macroseismic intensity and the EMS-98 damage grades have been considered for classifying the physical damage to the buildings. The calculated vulnerability indexes and vulnerability curves show that for engineered houses there is not any notable difference between the vulnerability of Iranian and Risk-UE building types. For the non-engineered houses, the vulnerability index of brick and steel structures is less than the corresponding values of the other unreinforced masonry buildings of Iran. The vulnerability index of unreinforced and masonry buildings of Iran are larger than the values of the similar types in Risk-UE and so the Iranian buildings are more vulnerable in this regard.     

Geological and archaeological evidence for post-Roman earthquake surface faulting at Cibyra,SW Turkey

The NE–SW-trending Burdur–Fethiye fault zone is one of the major active fault zones of southwestern Turkey and the ancient city of Cibyra is located on this zone. Segments of the Burdur–Fethiye fault zone have ruptured in the historical period and during the 20th century. A detailed investigation in the ancient city of Cibyra showed the presence of faults sinistrally offset sitting rows of the stadium up to 50 cm. In addition, there are broken corners of blocks, collapsed walls, broken columns, and tilted and toppled blocks in existing major buildings in the city centre. Field observations showed that fractures and associated damage at Cibyra were produced by a post-Roman earthquake, possibly during the 417-A.D.-earthquake which had an intensity of 9 on the MSK scale.     

断块大地构造与地震活动的构造物理研究

断块大地构造理论几乎涉及地震活动的各个方面： 1）地震记录表明不但是强震,大多数6级以上地震也分布在构造块体边界上,构造块体控制了地震分布; 2）地震活动规律体现在块体整体活动中。例如,鄂尔多斯地块周边单个断陷带的地震活跃期与平静期长短不一,无明显规律。但当把鄂尔多斯地块周边作为一个整体,其地震活动在时间上显示了准周期性; 3）地块运动通过周边断层交替活动实现。从断层活动相互作用的时间间隔和错动形式出发可把它分为强震交替活动型（又可分长时间间隔和短时间间隔两类）和强震与弱震或断层蠕动交替活动型。强震交替活动型中时间间隔很短的双震活动较早被发现。强震交替活动型中时间间隔很长的类型虽然不易识别,但是依赖于中国历史地震目录,还是发现鄂尔多斯地块周边山西断陷带与渭河断陷带在历史上的3次交替活动等; 强震与弱震或断层蠕动型的交替活动型很不容易被发现,仅在台网较密,观测条件较好的北京地区观测到。4）利用一些实验结果讨论了交替活动的规律。此外,结合断块大地构造理论对一些地震现象进行了讨论。     

桂林附近陷落地震分布,形成及特征

隐落地震是石灰岩喀斯特区溶洞或上洞塌陷所引起的特殊类型的地震,在我国南方及西南喀斯特区域分布较为广泛,是一类低震级高烈度的地震,在震中区造成较大的震灾。本文以桂林附近喀斯特区为研究范围,从古往今来的地震记录中分析提炼出其分布、形成及特征。     

1996～2005年中国大陆震害情况与减灾建议

地震是典型的突发性地质灾害,破坏性极大.本文首先对1996～2005年这10年间的大陆地震发生情况以及地震灾害情况进行了统计分析,列举了直接经济损失超过1亿元的重大地震灾害,指出大陆防震减灾要有地域特点;然后提出了一些防震减灾建议,如注意防范地震引发的次生灾害,加强建筑抗震设计和加固,推广使用现代信息技术,积极开展防震减灾能力评价,通过合理的城市规划和土地利用规划来减轻地震灾害.     

从昭通地震破坏实例看山区地震地面破坏特点

1974年5月11日3时25分,东经104度,北纬28.2度我国云南省昭通境内发生M=7.1地震。宏观震中为大关县以北,木杆公社钟(杜)家坪附近。震中烈度为IX度。震区为拔海2000米的滇东北高原地区,地面经受强烈切刻,山高坡陡,尤其震区西部,地形尤显陡峻。地形的坡度一般均在30°以上,主要河流的坡降平均为2.53%。该区地质情况比较复杂。地层分布主要为二迭纪阳新统灰岩,峨眉山玄武岩,三迭纪飞仙关砂页岩等等。     

Neotectonics and slope stabilization at the Alhambra, Granada, Spain

Over 600 years, the Alhambra Palace of Granada, Spain, (a World Heritage site) has been damaged by earthquakes and slope instability. The western part of San Pedro Cliff, on the northern slope of the palace is a compound fault scarp — fault-line scarp, modified by river erosion and latterly by successive slab falls. The plane of the fault with the largest throw (c. 7 m) outcrops in the innermost part of the escarpment, and is a normal fault with a NW–SE strike and steep SE dip. It is part of a set outcropping along the Alhambra hill. Fault activity may be very recent, perhaps related to historical earthquakes. Seismic risk at the Alhambra is considered to be moderate: there is earthquake damage of the Arab walls and barrier. The most significant historical damage occurred in 1431 and partially collapsed the Arab barrier. Extension associated with the faults loosens the ground and contributes to slab falls. The faults are also preferential water paths. Both the many cracks of the walls and collapses of the Alhambra barrier appear concentrated and aligned with the fault set.Stability analyses suggest that the factor of safety of the San Pedro slope under 1000-yr-return-period earthquake loading may drop below 1.0 and the critical slip surface could penetrate the Alhambra walls. To raise the safety factor above 1.0 and to counteract extensional stress in the cliff, an apparently environmentally acceptable solution with minimal visual impact is proposed. It consists of high-yield-stress wire mesh, post-tensioned by anchors, and coloured to blend with the cliff.     

Geological and archaeological evidence for post– Roman earthquake surface faulting at Cibyra,SW Turkey

Abstract

The NE-SW-trending Burdur–Fethiye fault zone is one of the major active fault zones of southwestern Turkey and the ancient city of Cibyra is located on this zone. Segments of the Burdur–Fethiye fault zone have ruptured in the historical period and during the 20th century. A detailed investigation in the ancient city of Cibyra showed the presence of faults sinistrally offset sitting rows of the stadium up to 50 cm. In addition, there are broken corners of blocks, collapsed walls, broken columns, and tilted and toppled blocks in existing major buildings in the city centre. Field observations showed that fractures and associated damage at Cibyra Produced by a post-Roman earthquake, possibly during the 417-A.D.-earthquake which had an intensity of 9 on the MSK scale. © 2001 Éditions scientifiques et médicales Elsevier SAS.     

Damage field and site effects: multidisciplinary studies of the 1964 earthquake series in Central Switzerland

Central Switzerland shows comparatively high seismic activity by Swiss standards. Many historical earthquakes are known and several of them caused damage. The last major event dates back to 1964 and has the characteristics of an earthquake swarm. Among dozens of felt shocks were two main shocks (Mw = 5 and 5.7) that moderately damaged a limited area with hundreds of buildings suffering loss. Our aim here was to reconstruct the damage field and to analyze whether it was influenced by site effects. Given the existence of a contemporary damage assessment and other historical sources, we could describe the damage field in detail. For about 95% of the affected buildings, we could reconstruct the location and extent of loss, using assessments from the European Macroseismic Scale (EMS 98). Spatial analysis of the resulting data showed that most losses were concentrated in the villages of Sarnen and Kerns. Damage to residential houses and barns was by far most frequent (90%), but expensive losses to the relatively few sacral buildings were responsible for almost 50% of the repair costs. We compared the damage data with deposit thickness and soil composition and carried out field experiments using H/V spectral ratios to measure the fundamental frequency of ground resonance at 75 sites to estimate the frequency band in which amplification occurs. Our results show that locations on both thick fluviatile sediments and large alluvial cones showed higher intensities than did other ground types. Moreover, at some sites, intensity was probably increased by a layer of weathered rock below thin deposits.     

Archaeoseismic record at the ancient Roman City of Baelo Claudia (Cádiz, south Spain)

This study represents the first paleoseismic approach in Spain in which archaeological remains are considered. The ancient Roman city of Baelo Claudia (1st–4th centuries AD), located at the axial zone of the Gibraltar Strait (Cadiz, south Spain), contains abundant disrupted architectural relics and ground collapses (i.e. landsliding, liquefacion) probably related to historic earthquake damage of intensity IX–X MSK. The archaeological stratigraphy of the city evidence two major episodes of abrupt city destruction bracketed in AD 40–60 and AD 350–395 separated by an intervening horizon of demolition for city rebuilding, otherwise characteristic for many earthquake-damaged archaeological sites in the Mediterranean. The second episode led the eventual city abandonment, and it is evidenced by good examples of column collapse, distortion, failure and breakdown of house and city walls, and pavement warping and disruptions documented during different archaeological excavations, which can be catalogued as secondary coseismic effects. Main damaged relicts observable today are the set of pop-up like arrays and warping developed in the ancient Roman pavement. Their analysis indicate an anomalous westwards ground displacement oblique to the main gentle southward slope of the topography, as also evidence failures, collapses and breakdown of walls and columns, suggesting that stress acted in a broad SW–NE/WSW–ENE orientation consistent whit the expectable motion along the largest NE–SW strike-slip faults of the zone, which in turn can be catalogued as seismic sources of moderate events (ca. 5 mb). Major disruptions and city abandonment were hesitantly related to relatively far strong earthquakes occurred during the late 4th century AD in the Mediterranean or western coast of Iberia by Menanteau et al. [Menanteau, L., Vanney, J.R., Zazo, C., 1983. Belo II : Belo et son environment (Detroit de Gibraltar), Etude physique d'un site antique. Pub. Casa de Velazquez, Serie Archeologie 4., Ed. Broccard, París.]. However, this study indicates that the occurrence of close moderate earthquakes jointly with the unstable character of the ground at the zone (site effect) is a more reliable hypothesis to explain the observed deformations.