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1.
EMERGEO Working Group 《地学学报》2010,22(1):43-51
An earthquake of Mw = 6.3 struck L'Aquila town (central Italy) on 6 April 2009 rupturing an ∼18-km-long SW-dipping normal fault. The aftershock area extended for a length of more than 35 km and included major aftershocks on 7 and 9 April and thousands of minor events. Surface faulting occurred along the SW-dipping Paganica fault with a continuous extent of ∼2.5 km. Ruptures consist of open cracks and vertical dislocations or warps (0.1m maximum throw) with an orientation of N130°–140°. Small triggered slip and shaking effects also took place along nearby synthetic and antithetic normal faults. The observed limited extent and small surface displacement of the Paganica ruptures with respect to the height of the fault scarps and vertical throws of palaeo-earthquakes along faults in the area put the faulting associated with the L'Aquila earthquake in perspective with respect to the maximum expected magnitude and the regional seismic hazard. 相似文献
2.
Earthquake-induced ground failures in Italy 总被引：8，自引：0，他引：8
The National Catalog of Ground Failures Induced by Strong Earthquakes in Italy (CEDIT), is described. The catalog holds data on ground failures triggered by the earthquakes that occurred in Italy in the last millennium and which had a nominal epicentral intensity equal to or greater than VIII in the Mercalli–Cancani–Sieberg (MCS) intensity scale. The ground effects reported in the catalog are the following: landslides, fractures, liquefaction, surface faulting, and topographic changes of the ground level (subsidence, settlements, tilting, and so on). Each effect is described in terms of seismological parameters of the triggering earthquake, site coordinates and administrative code, lithology and kinematic type of the ground failure. The catalog represents a tool to assess the susceptibility of geologic materials to ground shaking, and to validate predictive models of seismically induced ground displacements (scenarios of earthquake-induced geologic risks). In the context of this study, a simple statistical analysis of the database yielded useful relations between the parameters of the triggering earthquakes and the related effects. 相似文献
3.
The compositional data collected at three thermal springs in the Umbria region over a sampling period lasting two and a half hydrological years included the entire seismic sequence striking the Central Apennines (Italy) in 1997–1998. Wide temporal variations in the chemical composition and temperature of thermal waters were observed at all the sampling sites. The widest were recorded at the Triponzo sampling site, where a temperature drop of 2 °C and 20 °C preceded, by 4 days and 2 days, respectively, the occurrence of the event characterized by the deepest hypocentre of the entire seismic sequence. Despite such a macroscopic preseismic anomaly, the recorded variations were not related to single seismic events or to the release rate of the seismic energy. They actually seem to have been induced by permeability variations related to crustal deformation in the absence of elastic energy release and were thus linked to the whole seismogenic process. 相似文献
4.
Seismic geomorphology studies landforms which developed in connection with earthquakes. Among them, two different end members may be distinguished: 1) seismo-tectonic landforms, including surface faults and fractures, land uplift and subsidence at different scales, surface bulges, elongate ridges, and any other permanent ground deformations directly related to tectonic stress, and 2) seismo-gravitational landforms, such as landslides, deep-seated gravitational slope deformations, sinkholes, and fissures due to sediment compaction or liquefaction and sand blows, connected with both seismic shaking and gravitational stress.A clear-cut distinction between the two categories of landforms is not always easy to make (and in many instances not really useful), while there are, in many cases, ground effects that might be (and should be) considered as simultaneous combinations of seismo-tectonic and seismo-gravitational processes. This applies especially to surface fracturing and faulting which could be the combined result of tectonic stress, stress produced by seismic shaking, and gravitational stress.The objective of this paper is to review selected case histories mainly from Italy and the Mediterranean region, in order to show the importance of a comprehensive study of earthquake-generated landforms for understanding the seismicity level of the area under investigation. We argue that in earthquake prone areas, seismic landforms often constitute typical patterns (seismic landscapes) whose recognition, mapping and paleoseismological analysis may help in the evaluation of seismic hazards. 相似文献
5.
Sergio A. Sepúlveda William Murphy Randall W. Jibson David N. Petley 《Engineering Geology》2005,80(3-4):336-348
The 1994 Northridge earthquake (Mw = 6.7) triggered extensive rock slope failures in Pacoima Canyon, immediately north of Los Angeles, California. Pacoima Canyon is a narrow and steep canyon incised in gneissic and granitic rocks. Peak accelerations of nearly 1.6 g were recorded at a ridge that forms the left abutment of Pacoima Dam; peak accelerations at the bottom of the canyon were less than 0.5 g, suggesting the occurrence of topographic amplification. Topographic effects have been previously suggested to explain similarly high ground motions at the site during the 1971 (Mw = 6.7) San Fernando earthquake. Furthermore, high landslide concentrations observed in the area have been attributed to unusually strong ground motions rather than higher susceptibility to sliding compared with nearby zones. We conducted field investigations and slope stability back-analyses to confirm the impact of topographic amplification on the triggering of landslides during the 1994 earthquake. Our results suggest that the observed extensive rock sliding and falling would have not been possible under unamplified seismic conditions, which would have generated a significantly lower number of areas affected by landslides. In contrast, modelling slope stability using amplified ground shaking predicts slope failure distributions matching what occurred in 1994. This observation confirms a significant role for topographic amplification on the triggering of landslides at the site, and emphasises the need to select carefully the inputs for seismic slope stability analyses. 相似文献
6.
The role of rainfall in the landslide hazard: the case of the Avigliano urban area (Southern Apennines, Italy) 总被引：5，自引：0，他引：5
Mass movements varying in type and size, some of which are periodically reactivated, affect the urban area of Avigliano. The disturbed and remoulded masses consist of sandy–silty or silty–clayey plastic material interbedded with stone fragments and conglomerate blocks. Five landslides that were markedly liable to rainfall-associated instability phenomena were selected.
The relationships between landslides and rainfall were investigated using a hydrological and statistical model based on long-term series of daily rainfall data. The model was used to determine the return period of cumulative daily rainfall over 1–180 days. The resulting hydrological and statistical findings are discussed with the aim of identifying the rainfall duration most critical to landslides.
The concept of a precipitation threshold was generalized by defining some probability classes of cumulative rainfall. These classes indicate the thresholds beyond which reactivation is likely to occur. The probability classes are defined according to the return period of the cumulative rainfall concomitant with landslide reactivation. 相似文献
7.
In October 1862, Robert Mallet published an extensive study of a large earthquake that occurred on 16 December 1857, 150 km south-east of Naples. This event is one of the most destructive ever recorded in Italy. Although continental earthquakes of similar size are almost invariably associated with surface faulting, Mallet did not identify any surface rupture and subsequent workers have also failed to find surface traces. Using satellite images and aerial photographs as a guide, we examined two prominent Quaternary normal fault systems in the field. Flanking the Val d'Agri and the Val di Diano, both trend NW–SE and dip to the SW. The distribution of damage suggests that one or both moved in 1857. On one fault segment in Val d'Agri, we found a 2.5-m high scarp whose youthfulness and height suggest it is due to the 1857 earthquake. Comparison of the observed slip with rates derived from geomorphic evidence suggests a recurrence time for 1857 type events of about 3000 years. While the new data we provide are consistent with the event having a magnitude of M s ≈ 7.0, there are also grounds for supposing it might have been bigger. 相似文献
8.
地震与非地震诱发滑坡的运动特征对比研究 总被引：1，自引：1，他引：0
针对不同诱发机制的滑坡运动特征差异,以滑坡的总斜率和阻止系数为评价指标,分析滑坡的总斜率、阻止系数与滑坡规模、总能量的关系,对比研究了地震和非地震滑坡的总斜率、地形阻止系数的特征。研究结果表明：地震与非地震滑坡的规模越大在运动过程中受到的阻止作用越小;地震滑坡和非地震滑坡的总斜率都随滑坡规模和总能量增加而减小,但地震滑坡减小的速率大于非地震滑坡;地震滑坡的平均阻止系数约为0.4～0.5,而非地震滑坡的平均阻止系数约为同规模地震滑坡的40%～50%。因此,滑坡的运动特征不仅受滑坡规模及总能量控制,还显著地受滑坡的诱发机制和地形阻止等因素的影响。 相似文献
9.
One of the most significant effects of the 17 January, 1994 Northridge, California earthquake (M=6.7) was the triggering of thousands of landslides over a broad area. Some of these landslides damaged and destroyed homes and other structures, blocked roads, disrupted pipelines, and caused other serious damage. Analysis of the distribution and characteristics of these landslides is important in understanding what areas may be susceptible to landsliding in future earthquakes. We analyzed the frequency, distribution, and geometries of triggered landslides in the Santa Susana 7.5′ quadrangle, an area of intense seismic landslide activity near the earthquake epicenter. Landslides occurred primarily in young (Late Miocene through Pleistocene) uncemented or very weakly cemented sediment that has been repeatedly folded, faulted, and uplifted in the past 1.5 million years. The most common types of landslide triggered by the earthquake were highly disrupted, shallow falls and slides of rock and debris. Far less numerous were deeper, more coherent slumps and block slides, primarily occurring in more cohesive or competent materials. The landslides in the Santa Susana quadrangle were divided into two samples: single landslides (1502) and landslide complexes (60), which involved multiple coalescing failures of surficial material. We described landslide morphologies by computing simple morphometric parameters (area, length, width, aspect ratio, slope angle). To quantify and rank the relative susceptibility of each geologic unit to seismic landsliding, we calculated two indices: (1) the susceptibility index, which is the ratio (given as a percentage) of the area covered by landslide sources within a geologic unit to the total outcrop area of that unit; and (2) the frequency index [given in landslides per square kilometer (ls/km2)], which is the total number of landslides within each geologic unit divided by the outcrop area of that unit. Susceptibility categories include very high (>2.5% landslide area or >30 ls/km2), high (1.0–2.5% landslide area or 10–30 ls/km2), moderate (0.5–1.0% landslide area or 3–10 ls/km2), and low (<0.5% landslide area and <3 ls/km2). 相似文献
10.
Ground deformation monitoring by using the Permanent Scatterers Technique: The example of the Oltrepo Pavese (Lombardia, Italy) 总被引：2，自引：0，他引：2
The applicability of the Permanent Scatterers Synthetic Aperture Radar Interferometry (PSInSAR) technique for detecting and monitoring ground displacements was tested in the Oltrepo Pavese territory (Northern Italy, southern Lombardia), which could be representative of similar geological contexts in the Italian Apennines. The study area, which extends for almost 1100 km2, is characterized by a complex geological and structural setting and the presence of clay-rich sedimentary formations. These characteristics make the Oltrepo Pavese particularly prone to several geological hazards: shallow and deep landslides, subsidence and swelling/shrinkage of the clayey soils. The PSInSAR technique used in this study overcomes most of the limitations of conventional interferometric approaches by identifying, within the area of interest, a set of “radar benchmarks” (PS), where very precise displacement measurements can be carried out. More than 90,000 PS were identified by processing Synthetic Aperture Radar (SAR) images acquired from 1992 to 2001 by the European Remote Sensing satellites (ERS). The PSInSAR application at a sub-regional scale detected slow ground deformations ranging from + 5 to − 16 mm/year, and resulting from various processes (landslides, swelling/shrinkage of clay soils and water pumping). The PS displacements were analysed by collecting data obtained through geological, geomorphologic field surveys, geotechnical analysis of the soils and the information was integrated within a landslide inventory and the damaged building inventory. Despite the limited number of landslide bodies with PS (7% of the inventoried landslides), the PS data helped to revise the state of activity of several landslides. Furthermore, some previously unknown unstable slopes were detected. Two areas of uplift and two areas of subsidence were identified. 相似文献
11.
Twenty years of paleoseismology in Italy 总被引：1，自引：0，他引：1
Italy has one of the most complete and historically extensive seismic catalogues in the World due to a unique and uninterrupted flow of written sources that have narrated its seismic history since about the end of the Iron Age. Seismic hazard studies have therefore always been mainly based upon this huge mass of data. Nevertheless, the Italian catalogue probably “lacks” many M ≥ 6.5 events, the seismogenetic structures responsible for which are characterized by recurrence times that are longer than the time span covered by our historical sources. For these reasons, and as in other countries, earthquake data that in Italy have been derived from paleoseismological studies should finally become a necessary ingredient in seismic risk assessment. Indeed, over the past 20 years, some hundred trenches have been excavated, supplying reliable and conclusive data on the recent activities of many faults. Through to many robust datings of surface fault events, these studies have provided the ages of several unknown or poorly known M ≥ 6.5 earthquakes. Here, we summarize the state of the art of paleoseismology in Italy, and present a first catalogue of 56 paleoearthquakes (PCI) that occurred mainly in the past 6 kyr. The PCI integrates the historical/instrumental seismic catalogue, and extends it beyond the recurrence time of the seismogenetic faults (2000 ± 1000 yr). We feel confident that the use of the PCI will enhance future probabilistic seismic hazard assessment, and thus contribute to more reliable seismic risk mitigation programs. 相似文献
12.
A test of transferability for landslides susceptibility models under extreme climatic events: application to the Messina 2009 disaster 总被引：2，自引：1，他引：1
A model building strategy is tested to assess the susceptibility for extreme climatic events driven shallow landslides. In fact, extreme climatic inputs such as storms typically are very local phenomena in the Mediterranean areas, so that with the exception of recently stricken areas, the landslide inventories which are required to train any stochastic model are actually unavailable. A solution is here proposed, consisting in training a susceptibility model in a source catchment, which was implemented by applying the binary logistic regression technique, and exporting its predicting function (selected predictors regressed coefficients) in a target catchment to predict its landslide distribution. To test the method, we exploit the disaster that occurred in the Messina area (southern Italy) on 1 October 2009 where, following a 250-mm/8-h storm, approximately two thousand debris flow/debris avalanches landslides in an area of 21 km2 triggered, killing 37 people and injuring more than 100, and causing 0.5 M € worth of structural damage. The debris flows and debris avalanches phenomena involved the thin weathered mantle of the Varisican low to high-grade metamorphic rocks that outcrop in the eastern slopes of the Peloritani Mounts. Two 10-km2-wide stream catchments, which are located inside the storm core area, were exploited: susceptibility models trained in the Briga catchment were tested when exported to predict the landslides distribution in the Giampilieri catchment. The prediction performance (based on goodness of fit, prediction skill, accuracy and precision assessment) of the exported model was then compared with that of a model prepared in the Giampilieri catchment exploiting its landslide inventory. The results demonstrate that the landslide scenario observed in the Giampilieri catchment can be predicted with the same high performance without knowing its landslide distribution: we obtained, in fact, a very poor decrease in predictive performance when comparing the exported model to the native random partition-based model. 相似文献
13.
Analysis of a spatial distribution of landslides triggered by the 2004 Chuetsu earthquakes of Niigata Prefecture, Japan 总被引：15，自引：1，他引：15
On October 23, 2004, a series of powerful earthquakes with a maximum M
w = 6.6 located near the western coast of northern Honshu struck parts of northern Japan, particularly Niigata Prefecture;
these earthquakes were known as the Chuetsu event. Thousands of landslides, as a secondary geotechnical hazard associated
with these earthquakes, were triggered over a broad area; these landslides were of almost all types. The purpose of this study
was to detect correlations between landslide occurrence with geologic and geomorphologic conditions, slope geometry, and earthquake
parameters using two indexes based on Geographic Information Systems (GIS). In the study area, the landslide–area ratio (LAR),
which is defined as the percentage of the area affected by landslides, was 2.9%, and the landslide concentration (LC), the
number of landslides per square kilometer, was 4.4 landslides/km2, which is much more than other reported cases of seismic activity with the same magnitude. This was possibly due to heavy
rainfall just before the Chuetsu earthquakes. Statistical analyses show that LAR has a positive correlation with slope steepness
and distance from the epicenter, while LC is inversely correlated with distance from the epicenter. The Wanazu Formation had
the most concentrated landslide activity, followed by the Kawaguchi, Ushigakubi, Shiroiwa and Oyama Formations, although the
Wanazu Formation occupied only 4.5% of the total area of geological units. With 8.2% of the area affected by seismic landslides,
the Kawaguchi Formation had the highest LAR. It was followed by the Shiroiwa, Ushigakubi and Wanazu Formations with LAR ranging
from 4.6% to 6.0%. For lots of geological subunits, landslides are more frequent in a range of slope angles between 15° and
40°. The susceptibility to landsliding of each geologic unit was thus evaluated to correlate with slope steepness. It was
also noted that the effects of the earthquakes were made far worse by antecedent rainfall conditions induced by a␣typhoon,
and further research emphasizing the role of antecedent rainfall was discussed. 相似文献
14.
The NW–SE-trending Dinar fault is an active normal fault upon which the 1 October 1995 earthquake ( M = 6.1) occurred. The 1995 earthquake resulted in a c. 10-km-long surface rupture with the south side down-thrown by 50 cm. Investigations of two trench sites perpendicular to the 1995 rupture suggest at least two prior large earthquakes in historical times. Radiocarbon dates and historical records constrain the age of events between 1500 bc and ad 53, event 2 possibly coinciding with the earthquake that damaged Dinar (the ancient city of Apamea Kibotos) in c. 80 bc and event 1 around 1500 bc. Surface displacements determined for events 1 and 2, compared to the 1995 surface faulting, indicate that M > 6.8 earthquakes were associated with each rupture. Using the total displacement in trenches, a slip rate of about 1 mm yr−1 can be estimated for the Dinar fault. Observations suggest that the return period for large earthquakes in the Dinar area is about 1500–2000 years. 相似文献
15.
On far field occurrence of seismically induced landslides 总被引：1，自引：0，他引：1
Earthquakes may induce landslides at large distances from the epicentral area. In the last two decades, there have been many studies of this phenomenon to determine the causes that contribute to the occurrence of landslides at very long distances from earthquake epicenter. In this study, which is based on previously published works, a worldwide database comprising 270 earthquakes, including 150 during the instrumental period, was compiled to analyse the features of those landslides that occur at much further distances than maximum expected distances. From the analysis of the compiled data, it was observed that susceptible slopes can be grouped into five broad geological categories: jointed rock, marly–clayey (cohesive) soils, granular alluvial and/or colluvial sediments, volcanic soils, and residual soil slopes. These categories were equally likely to be associated with far field disrupted landslides, whereas far field coherent landslides were more frequent on cohesive soil slopes. Other factors, along with slope susceptibility may also contribute to far field landslides and increase the size of the area affected. Among these factors, site effects, antecedent rain and occurrence of seismic series have been cited. The analysis of available data also showed that for events of the same magnitude, far field disrupted landslides may occur at greater distances than coherent ones. The same database has also been employed to determine, for the first time, the upper bound curves for the maximum observed epicentral distances of several types of landslides and the maximum area observed to be affected by landslides, both based on the epicentral intensity of the events. 相似文献
16.
The hazard assessment of potential earthquake-induced landslides is an important aspect of the study of earthquake-induced landslides. In this study, we assessed the hazard of potential earthquake-induced landslides in Huaxian County with a new hazard assessment method. This method is based on probabilistic seismic hazard analysis and the Newmark cumulative displacement assessment model. The model considers a comprehensive suite of information, including the seismic activities and engineering geological conditions in the study area, and simulates the uncertainty of the intensity parameters of the engineering geological rock groups using the Monte Carlo method. Unlike previous assessment studies on ground motions with a given exceedance probability level, the hazard of earthquake-induced landslides obtained by the method presented in this study allows for the possibility of earthquake-induced landslides in different parts of the study area in the future. The assessment of the hazard of earthquake-induced landslides in this study showed good agreement with the historical distribution of earthquake-induced landslides. This indicates that the assessment properly reflects the macroscopic rules for the development of earthquake-induced landslides in the study area, and can provide a reference framework for the management of the risk of earthquake-induced landslides and land planning. 相似文献
17.
Colby A. Smith Martin Sundh Henrik Mikko 《International Journal of Earth Sciences》2014,103(6):1711-1724
In Sweden, knowledge of the location and timing of glacially induced faulting and seismicity is critical to effective engineering of a long-term nuclear disposal facility. To improve understanding and modeling of the complex ice-induced and tectonic stresses associated with glacially induced faulting, field studies detailing the location and timing of movement of such structures are required. Although the fault has not been confirmed in the bedrock, multi-proxy surficial geologic evidence indicates that the recently discovered scarp in Bollnäs is such a structure. Machine-excavated trenches across the scarp reveal landsliding down the scarp and, in one location, faulted and vertically offset fine-grained glacial sediments. The presence of water-escape structures in trenches excavated on a topographic high strongly suggests a co-seismic origin derived from earthquake magnitudes >5.5. Numerous landslides in till exist in the region as well. Four slopes with landslides were examined in detail, and the factors of safety for these slopes indicate stable conditions and suggest a seismic trigger. Basal radiocarbon dates from peat bogs located stratigraphically above the landslides provide minimum limiting ages for the co-seismic landslides. The oldest date indicates sliding prior to 10,180 calendar years before the present. The proposed Bollnäs Fault is 400 km south of the so called Lapland Fault Province. To date, it is the southernmost confirmed glacially induced fault in Sweden. The results of this study are consistent with existing modeling results that indicate fault instability in this region of central Sweden following deglaciation. 相似文献
18.
The results of seismotectonic study of the epicentral zone of the major earthquake in northern Kamchatka oblast are presented. Primary and secondary surface seismic dislocations were revealed. The exposed seismic source as a complex system of seismic faults up to 140 km in total length was found and mapped in detail. The system consists of three en echelon arranged NE-oriented segments about 16, 45, and 75 km long. The general strike of the fault system coincides with the orientation of the ridges in the Koryak Highland. The kinematics of the longest northeastern segment is reverse faulting of the southeastern wall combined with right-lateral strike-slip faulting. The maximum vertical and horizontal separations are 3 and 1.5 m, respectively. Vibration fractures, griffons, landslides, and rockfalls were revealed and documented as secondary seismic dislocations. The indications of paleoseismic dislocations were studied and documented as well. The age of paleoseismic events was determined with radiocarbon method from soil samples. The seismic source is confined to the boundary of the North American and Bering Sea lithospheric plates and exhibits its internal structure for a long distance. Seismic events testify to recent geological activity of the zone of interaction between the lithospheric plates. The collected data provide insights into the structure of the seismic source and its tectonic setting at the active continental margin of Asia. 相似文献
19.
滑坡分类研究一直是滑坡研究的基础和重点。通过对山西煤矿区滑坡灾害的工程实践和大量的调查统计分析,根据滑坡地层结构、岩性特征、诱发机制及运动特征等因素将山西煤矿区滑坡归结为5种类型:顺基岩面推移-滑动型黄土滑坡;蠕滑-挤出型黄土滑坡;水浸溜滑型黄土滑坡;煤层自燃倾覆-拉裂滑移型岩质滑坡;受节理控制的蠕滑-张裂型岩质滑坡。研究结果发现:黄土滑坡滑带土一般为松散土层,岩质滑坡的滑面为软弱结构面（多为泥岩薄层）或煤线;除溜滑型黄土滑坡滑动速度较快外,其他为低速滑坡,其典型特点是历时长,滑距短,致灾范围小,但滑坡推力大,破坏力强,往往造成更大损失。该研究进一步细化了滑坡分类的内容,其成果可对山西矿区及类似滑坡地质灾害的防治提供指导。 相似文献
20.
Giacomo D’Amato Avanzi Francesco Falaschi Roberto Giannecchini Alberto Puccinelli 《Natural Hazards》2009,50(3):591-603
This study aims at contributing to the soil slip susceptibility assessment in a typical basin of the southern Apuan Alps,
Italy. On June 1996, this basin (Cardoso Torrent, 13 km2 large) was hit by an extremely heavy rainstorm (maximum intensity of about 160 mm/h), which caused many landslides (debris
slide–debris flows) and valley bottom flows (hyperconcentrated flows), destruction and deaths. Detailed surveys provided the
characterization of the main factors (geological, geomorphologic, hydrological, hydrogeological and geotechnical) which contributed
in triggering landslides. In order to evaluate the soil slip susceptibility in this area, a physically based model was applied
and a GIS analysis of digital elevation model was performed. This approach couples a mechanical model based on an infinite
slope form of the Mohr–Coulomb failure criterion, and a steady-state hydrological one (a modified version of Shalstab, which
considers the cohesion of the debris material potentially involved in landsliding). GIS techniques allowed evaluating the
effects of topographic convergence and drainage area on slope failure. In this way, based on the infiltration rate, the triggering
of the June 1996 landslides was simulated and the critical rainfall thresholds assessed at about 200–250 mm/24 h. 相似文献