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1.
Seismic risk scenarios are obtained for an informal settlement in Mérida (Venezuela), which is representative of an important
number of urban areas in earthquake-prone regions of the developing world. The vulnerability indices of the buildings range
between 0.64 and 0.80 on a scale of 0 to 1. In an intensity IX earthquake scenario, more than 32% of the buildings would suffer
damage of grade 4 (extensive) or greater. A structural analysis of the buildings in the study area shows that they are unsafe
for gravity loads, and that the seismic demands exceed the strength of the constructions. Simple and comparatively inexpensive
measures can improve the seismic performance of these buildings; the vulnerability can be reduced by about 51%. In an intensity
IX earthquake scenario, the expected economic loss before retrofitting the buildings is US5.36 million, with 275 fatalities; once retrofit has been carried out, the resulting figures are US5.36 million, with 275 fatalities;
once retrofit has been carried out, the resulting figures are US0.39 million and 10 fatalities. Retrofit would cost US1.04 million, whereas reconstruction would cost US1.04
million, whereas reconstruction would cost US19 million. 相似文献
3.
Quantitative risk assessments (QRAs) for landslide hazards are increasingly being executed to determine an unmitigated level
of risk and compare it with risk tolerance criteria set by the local or federal jurisdiction. This approach allows urban planning
with a scientific underpinning and provides the tools for emergency preparedness. Debris-flow QRAs require estimates of the
hazard probability, spatial and temporal probability of impact (hazard assessment) and vulnerability of the elements at risk.
The vulnerability term is perhaps the most difficult to estimate confidently because (a) human death in debris flows is most
commonly associated with building damage or collapse and is thus an indirect consequence and (b) the type and scale of building
damage is very difficult to predict. To determine building damage, an intensity index ( I
DF) was created as the product of maximum expected flow depth d and the square of the maximum flow velocity v ( I
DF = dv
2). The I
DF surrogates impact force and thus correlates with building damage. Four classes of building damage were considered ranging
from nuisance flood/sedimentation damage to complete destruction. Sixty-six well-documented case studies in which damage,
flow depth and flow velocity were recorded or could be estimated were selected through a search of the global literature,
and I
DF was plotted on a log scale against the associated damage. As expected, the individual damage classes overlap but are distinctly
different in their respective distributions and group centroids. To apply this vulnerability model, flow velocity and flow
depth need to be estimated for a given building location and I
DF calculated. Using the existing database, a damage probability ( P
DF) can then be computed. P
DF can be applied directly to estimate the likely insurance loss or associated loss of life. The model presented here should
be updated with more case studies and is therefore made openly available to international researchers who can access it at
. 相似文献
5.
A geotechnical information system (GTIS) was constructed within a spatial geographic information system (GIS) framework to
reliably predict geotechnical information and accurately estimate site effects at Gyeongju, an urban area in South Korea.
The system was built based on both collected and performed site investigation data in addition to acquired geo-knowledge data.
Seismic zoning maps were constructed using the site period ( T
G) and mean shear wave velocity to a depth of 30 m ( V
S30), and these maps were presented as a regional strategy to mitigate earthquake-induced risks in the study area. In particular,
the T
G distribution map indicated the susceptibility to ground motion resonance in periods ranging from 0.2 to 0.5 s and the corresponding
seismic vulnerability of buildings with two to five stories. Seismic zonation of site classification according to V
S30 values was also performed to determine the site amplification coefficients for seismic design and seismic performance evaluation
at any site and administrative subunit in the study area. In addition, we investigated the site effects according to subsurface
and surface ground irregularities at Gyeongju by seismic response analyses in time domains based on both two- and three-dimensional
spatial finite element models, which were generated using spatial interface coordinates between geotechnical subsurface layers
predicted by the GTIS. This practical study verified that spatial GIS-based geotechnical information can be a very useful
resource in determining how to best mitigate seismic hazards, particularly in urban areas. 相似文献
6.
Damage caused by the earthquake of 7 December 1986 ( M = 5.7) and its aftershocks in low-storey residential buildings in the town of Strazhitza, Bulgaria, situated in the epicentral zone are systematized. A scale of damages is compiled for two types of buildings which is coordinated with the MSK-64 scale. The territorial distribution of the seismic intensity is compared with the results of the detailed engineering-geological study. A correlation between the Quarternary deposit thickness and the observed seismic intensity is obtained.Paper presented at the 21st general assembly of the European Seismological Commission held in Sofia, 1988. 相似文献
7.
On March 20, 2006, an earthquake ( M
w = 5.3; SED) struck the mountainous region of the Babors chain (Wilaya of Bejaia, northeast Algeria). The seismic epicenter
was located near the Kherrata village. This earthquake was felt on a large area of the northeastern part of Algeria. It reached
an intensity of VII (EMS scale) at the Laalam village, situated at about 20 km northeast of Kherrata. Here, many old and recent
houses were damaged or collapsed totally, four people died and 68 were injured. Field investigations revealed that these casualties
were caused by a landslide triggered by the earthquake. Many fissures were visible on ground throughout the site. They were
generated by both sliding and settling phenomena. The Laalam site is prone to landslide, as revealed by some evidences on
old instabilities. This is due to two main factors: local geomorphology and geology. These factors intervene synchronously
for reducing the slope instability at the Laalam village. The March 20, 2006 Kherrata earthquake was the trigger that released
the Laalam landslide. 相似文献
8.
The results of detailed studies of the January 6, 2006, Balei earthquake ( K
p = 13.1, M
b = 4.7 [7]), which occurred in an almost aseismic area of the east Trans-Baikal Region, are presented. The focal mechanism
and dynamical characteristics of the focus are considered, and the structural-tectonic position of the focus is analyzed.
It is supposed that the focus of this seismic event coincides with an activated segment of the northwest-striking Balei-Darasun
fault. The maximal observed macroseismic intensity was 5–6 points by the MSK-64 scale (in the town of Baleis). The origination
of foci for the earthquake with such intensity and magnitude takes place substantially owing to subhorizontal northeastern
compression, the varied-rank block structure of the medium, and low rate values of tectonic motions; on aggregate, all these
factors promote the accumulation of stresses in the Earth’s crust. The obtained data can be useful for the purpose of assessment
in seismic danger of the region. 相似文献
9.
This study outlines an improved method, MLPI (modified leaching potential index) model, for delineating and mapping groundwater vulnerability and assessing groundwater vulnerability to contaminants, including degradable contaminants, radioactive elements and nondegradable pollutants. The primary objective is to produce specific sensitivity maps at city or county scale that can be used for recognition of aquifer sensitivity and for protection of groundwater quality. Groundwater vulnerability assessment using the MLPI method is applied to Datong city, Shanxi Province, with the following conclusions: (1) specific vulnerability was differentiated and ; (2) groundwater vulnerability is of temporal variation. 相似文献
10.
Fresh groundwater from intergranular and carbonate aquifers are considered as the valuable resources for domestic, agricultural and industrial water supplies of the Iraqi Kurdistan Region. A comprehensive approach to groundwater protection using the intrinsic vulnerability, hazard and risk intensity mapping was proposed by the European COST Action 620. The current article applied all the components of the above mentioned Pan-European approach to assess the risk harmfulness in the Sulaimani sub-basin by combining hydrogeological parameters using the DRASTIC system and the hazard components by taking the product of the weighted hazard value (H I), the ranking factor (Q n) and the reduction factor (R f). The hazard map was constructed from twenty-six hazard feature types of the point, line and polygon. Their distributions, extents and of harmfulness degrees vary sharply from one place to another. Results of the risk intensity map divided the area into five classes as “no or very low, low, moderate, high and very high” risk zones. Fortunately, the majority of the area of interest is classified as very low to low contamination potential due to the limited impact of hazards as well as low groundwater vulnerabilities. The zones with moderate-risk potentials clustered in industrialized areas. 相似文献
11.
The detrimental effects of an earthquake are strongly influenced by the response of soils subjected to dynamic loading. The behavior of soils under dynamic loading is governed by the dynamic soil properties such as shear wave velocity, damping characteristics and shear modulus. Worldwide, it is a common practice to obtain shear wave velocity (V
s in m/s) using the correlation with field standard penetration test (SPT) N values in the absence of sophisticated dynamic field test data. In this paper, a similar but modified advanced approach has been proposed for a major metro city of eastern India, i.e., Kolkata city (latitudes 22°20′N–23°00′N and longitudes 88°04′E–88°33′E), to obtain shear wave velocity profile and soil site classification using regression and sensitivity analyses. Extensive geotechnical borehole data from 434 boreholes located across 75 sites in the city area of 185 km2 and laboratory test data providing information on the thickness of subsoil strata, SPT N values, consistency indices and percentage of fines are collected and analyzed thoroughly. A correlation between shear wave velocity (V
s) and SPT N value for various soil profiles of Kolkata city has been established by using power model of nonlinear regression analysis and compared with existing correlations for other Indian cities. The present correlations, having regression coefficients (R
2) in excess of 0.96, indicated good prediction capability. Sensitivity analysis predicts that significant influence of soil type exists in determining V
s values, for example, typical silty sand shows 30.4 % increase in magnitude of V
s as compared to silt of Kolkata city. Moreover, the soil site classification shows Class D and Class E category of soil that exists typically in Kolkata city as per NEHRP (Recommended provisions for seismic regulations for new buildings and other structures—Part 1: Provisions. Prepared by the Building Seismic Safety Council for the Federal Emergency Management Agency (Report FEMA 450), Washington, DC, 2003) guidelines and thereby highlighting the seismic vulnerability of the city. The results presented in this study can be utilized for seismic microzonation, ground response analysis and hazard assessment for Kolkata city. 相似文献
12.
The evaluation of the combined influence of rainfall patterns (in terms of mean intensity and duration) and the geomorphological
and mechanical characteristics of hillslopes on their stability conditions is a major goal in the assessment of the shallow
landslide triggering processes. Geographic Information Systems (GIS) represent an important tool to develop models that combine
hydrological and geomechanical analyses for the evaluation of slope stability, as they allow to combine information concerning
rainfall characteristics with topographic and mechanical properties of the slopes over wide areas. In this paper, a GIS-based
code is developed to determine physically based intensity/duration rainfall thresholds at the local scale. Given the rainfall
duration and the local geometric, hydrological and mechanical characteristics of the slopes, the code evaluates the spatial
distribution of the minimum rainfall intensity that triggers shallow landslides and debris flows over a given area. The key
feature of the code is the capability of evaluating the time t
p
required to reach the peak pore pressure head on the failure surface and computing the corresponding critical intensity/duration
thresholds based on post-event peak pore pressures. The reliability of the model is tested using a set of one-dimensional
analyses, comparing the physically based thresholds obtained for three different slopes with some empirical rainfall thresholds.
In a log–log scale, the thresholds provided by the model decrease linearly with increased rainfall duration and they are bracketed
by the empirical thresholds considered. Finally, an example of application to a study area of the Umbria region in central
Italy is presented, describing the capability of the model of providing site-specific thresholds for different rainfall scenarios. 相似文献
14.
Groundwater vulnerability modeling is an alternative approach to evaluate groundwater contamination especially in areas affected by intensive anthropogenic activities. However, the DRASTIC model as a well-known method to assess groundwater vulnerability suffers from the inherent uncertainty associated with its seven essential parameters. In this study, three different fuzzy logic (FL) models (Sugeno fuzzy logic, Mamdani fuzzy logic, and Larsen fuzzy logic) are adopted to improve the DRASTIC system to be more realistic. The vulnerability map of groundwater from multiple aquifer systems (i.e., karstic, alluvium, and complex) in Basara basin, Iraq, was created using the FL models. Validation of the FL models results using NO 3-N concentration obtained from wells and springs of the study area indicating that all of the three FL models are applicable for improving the DRASTIC model. However, each of the FL models has its own advantages for groundwater vulnerability estimation in different types of aquifer systems in the Basara basin. Therefore, this study proposes the supervised committee fuzzy logic (SCFL) as a multimodel method to combine the advantages of individual FL models. The SCFL method confirms that no water well with high NO 3-N levels would be classified as low risk and vice versa. The study suggests that this approach has provided a convenient estimation of pollution risk in the study area and therefore, a more accurate prediction of the intrinsic vulnerability to pollution in the multiple aquifer system can be achieved through SCFL method. 相似文献
15.
The expected fraction of buildings lost in the event of an earthquake of a given intensity can be considered as a useful indicator of the seismic vulnerability of a small urban nucleus and can be used for the evaluation of seismic risk on a regional scale. This work describes a procedure for quantifying this indicator through data obtained from the buildings which constitute the nucleus during rapid on-site surveys. The knowledge on which the procedure is based is that given by the observed vulnerability of old Italian centres. 相似文献
16.
The Cascadia margin is capable of generating large magnitude seismic-tsunami. We use a 1:500 year tsunami hazard flood layer
produced during a probabilistic tsunami hazard assessment as the input to a pilot study of the vulnerability of residential and commercial buildings in Seaside, OR, USA. We map building
exposure, apply the Papathoma Tsunami Vulnerability Assessment Model to calculate building vulnerability and estimate probable maximum loss (PML) associated with a 1:500 year tsunami flood. Almost US$0.5 billion worth of buildings would be inundated, 95% of single
story residential and 23% of commercial buildings would be destroyed with PML’s exceeding US$0.5 billion worth of buildings would be inundated, 95% of single
story residential and 23% of commercial buildings would be destroyed with PML’s exceeding US116 million. These figures only
represent a tiny fraction of the total values of exposed assets and loss that would be associated with a Cascadia tsunami
impacting the NW Pacific coast. Not withstanding the various issues associated with our approach, this study represents the
first time that PML’s have ever been calculated for a Cascadia type tsunami, and these results have serious implications for
tsunami disaster risk management in the region. This method has the potential to be rolled out across the United States and
elsewhere for estimating building vulnerability and loss to tsunami. 相似文献
17.
Landslides are the most common natural disasters in mountainous regions, being responsible for significant loss of life as well as damage to critical infrastructure and properties. As the world population grows, people tend to move to higher locations to construct buildings, thereby making structures vulnerable due to landslides. This paper discusses previous research on the vulnerability assessment of structures exposed to landslides and presents a modified semi-quantitative approach to assess the scenario-based physical vulnerability of buildings based on their resistance ability and landslide intensity. Resistance ability is determined by integrating expert knowledge-based resistance factors assigned to five primary building parameters. Landslide intensity matrix defining different intensity levels is proposed based on combinations of landslide velocity and volume. Physical vulnerability of buildings is estimated and classified as class I, II or III for scenario-based low to very high landslide intensity. Finally, the application of the model is illustrated with a case study of 71 buildings from Garhwal Himalayas, India. 相似文献
18.
High alpine karst plateaus are recharge areas for major drinking water resources in the Alps and many other regions. Well-established
methods for the vulnerability mapping of groundwater to contamination have not been applied to such areas yet. The paper characterises
this karst type and shows that two common vulnerability assessment methods (COP and PI) classify most of the areas with high
vulnerability classes. In the test site on the Hochschwab plateau (Northern Calcareous Alps, Austria), overlying layers are
mostly absent, not protective or even enhance point recharge, where they have aquiclude character. The COP method classifies
82% of the area as highly or extremely vulnerable. The resulting maps are reasonable, but do not differentiate vulnerabilities
to the extent that the results can be used for protective measures. An extension for the upper end of the vulnerability scale
is presented that allows identifying ultra vulnerable areas. The proposed enhancement of the conventional approach points out that infiltration conditions are of key importance
for vulnerability. The method accounts for karst genetical and hydrologic processes using qualitative and quantitative properties
of karst depressions and sinking streams including parameters calculated from digital elevations models. The method is tested
on the Hochschwab plateau where 1.7% of the area is delineated as ultra vulnerable. This differentiation could not be reached
by the COP and PI methods. The resulting vulnerability map highlights spots of maximum vulnerability and the combination with
a hazard map enables protective measures for a manageable area and number of sites. 相似文献
19.
Quantitative X‐ray maps of composition from a chlorite, K‐white mica, albite, quartz and garnet bearing thin section from a Sambagawa blueschist facies metapelite were combined with a multi‐equilibrium calculation method to calculate a P– T‐Fe 3+/Fe 2+‐deformation map at the millimetre scale. The studied sample was chosen because elongated chlorite crystallization tails (pressure shadows) rimmed by phengite are present, which is an appropriate assemblage for the quantification of the P– T evolution. Chlorite temperature and Fe 3+ content maps were calculated by successive iterations for each pixel analysis of Fe 3+ until convergence of the four chlorite‐quartz‐H 2O equilibria that can be written using the Fe‐ and Mg‐amesite, clinchlore, daphnite and sudoite chlorite end‐members. The calculated map of Fe 2+/Fe 3+ in chlorite is in good qualitative agreement with the in situ mapping of this ratio using XANES (X‐ray absorption near edge structure) techniques. The temperature map indicates that high temperature chlorite zones with low Fe 3+ contents alternate with lower temperature zones and higher Fe 3+ contents in the crystallization tail. Late fractures perpendicular to the elongation axis of the tail are filled by very low temperature chlorite (<250 °C) showing Fe 3+/Fe total up to 0.4. Groups of chlorite and mica pixels were then identified based on compositional and structural criteria, and a P– T‐deformation map was calculated using representative analyses of these groups. The calculated P– T‐deformation map suggests that in contrast to chlorite, the composition of most mica did not change significantly during exhumation. Mica reequilibrated in late EW shear bands only. EW shearing was already active at 0.1 GPa, 500 °C, which corresponds to the peak temperature (and probably pressure) conditions, at reduced redox conditions. The intensity of deformation probably decreased with decrease in temperature to ~350–400 °C. At this temperature, a second main deformation event corresponding to a further EW stretching occurred and was still active below 250 °C and more oxidizing conditions. These results indicate that the scale at which P– T data can be obtained is now close to the scale of observation of structural geologists. A close link between deformation and mineral reaction is therefore possible at the microscopic scale, which provides information about the relationship between deformation and mineral reactivity, the modalities of deformation with time and the P– T conditions at which it occurred. 相似文献
20.
Jordan Valley is one of the important areas in Jordan that involves dense agricultural activities, which depend on groundwater resources. The groundwater is exploited from an unconfined shallow aquifer which is mainly composed of alluvial deposits. In the vicinity of the Kafrein and South Shunah, the shallow aquifer shows signs of contamination from a wide variety of non-point sources. In this study, a vulnerability map was created as a tool to determine areas where groundwater is most vulnerable to contamination. One of the most widely used groundwater vulnerability mapping methods is SINTACS, which is a point count system model for the assessment of groundwater pollution hazards. SINTACS model is an adaptation for Mediterranean conditions of the well-known DRASTIC model. The model takes into account several environmental factors: these include topography, hydrology, geology, hydrogeology, and pedology. Spatial knowledge of all these factors and their mutual relationships is needed in order to properly model aquifer vulnerability using this model. Geographic information system was used to express each of SINTACS parameters as a spatial thematic layer with a specific weight and score. The final SINTACS thematic layer ( intrinsic vulnerability index) was produced by taking the summation of each score parameter multiplied by its specific weight. The resultant SINTACS vulnerability map of the study area indicates that the highest potential sites for contamination are along the area between Er Ramah and Kafrein area. To the north of the study area there is a small, circular area which shows fairly high potential. Elsewhere, very low to low SINTACS index values are observed, indicating areas of low vulnerability potential. 相似文献
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