Probabilistic Seismic Hazard Assessment of the Kermanshah-Sanandaj Region of Western Iran

2007 ◽  
Vol 23 (1) ◽  
pp. 175-197 ◽  
Author(s):  
Elham Shabani ◽  
Noorbakhsh Mirzaei

Seismic hazard assessment and zoning of the Kermanshah-Sanandaj region in western Iran is conducted using probabilistic approach. Two maps have been prepared to indicate the earthquake hazard of the region in the form of iso-acceleration contour lines. They display a probabilistic estimate of peak ground acceleration (PGA) over bedrock for the return periods of 475 and 50 years. A uniform catalog of earthquakes containing historical and instrumental events covering the period from the eleventh century A.D. to 2003 is used. Twelve potential seismic sources are modeled as area sources in the region. Seismicity parameters are evaluated using the method in which magnitude uncertainty and incompleteness of earthquake data are considered. Seismic hazard assessment is carried out for a grid of 357 points with 0.1° intervals using the SEISRISKIII computer program for the study area encompassed by the 46–48° E longitudes and 34–36° N latitudes. This region includes the most active segments of the Zagros Main Recent Fault; among them, the Sahneh and Nahavand faults have a well-known history of intense seismic activity. PGA values for this region are estimated to be 0.35 g and 0.20 g for 475- and 50-years return periods, respectively.

2001 ◽  
Vol 17 (3) ◽  
pp. 399-415 ◽  
Author(s):  
Jamal A. Abdalla ◽  
Yahia E-A. Mohamedzein ◽  
A. Abdel Wahab

This paper presents seismic hazard assessment and seismic zoning of Sudan and its vicinity based on probabilistic approach. The area studied lies between 22° E- 45° E and 0° - 24° N. Tectonics of Sudan and its vicinity is first reviewed. An updated NOAA catalogue, containing both historical and instrumental events and covering the period from 700 A.D. to 1993 is then used. Seismic source regions are modeled and relationships between earthquake magnitude and earthquake frequency are established. A modified attenuation relation is used. Seismic hazard assessment is then carried out for 60 km interval grid points. Seismic hazard maps of the studied area based on peak ground acceleration (PGA) for 10% probability of exceedance for time-spans of 50, 100, 200 and 250 years are presented. The results showed that the PGA ranges from 0.02g for low seismic activity regions to around 0.62g for high seismic activity regions. A seismic zone map is also shown for 475 years return period.


2010 ◽  
Vol 10 (1) ◽  
pp. 25-39 ◽  
Author(s):  
G-A. Tselentis ◽  
L. Danciu

Abstract. Seismic hazard assessment represents a basic tool for rational planning and designing in seismic prone areas. In the present study, a probabilistic seismic hazard assessment in terms of peak ground acceleration, peak ground velocity, Arias intensity and cumulative absolute velocity computed with a 0.05 g acceleration threshold, has been carried out for Greece. The output of the hazard computation produced probabilistic hazard maps for all the above parameters estimated for a fixed return period of 475 years. From these maps the estimated values are reported for 52 Greek municipalities. Additionally, we have obtained a set of probabilistic maps of engineering significance: a probabilistic macroseismic intensity map, depicting the Modified Mercalli Intensity scale obtained from the estimated peak ground velocity and a probabilistic seismic-landslide map based on a simplified conversion of the estimated Arias intensity and peak ground acceleration into Newmark's displacement.


2015 ◽  
Vol 58 (1) ◽  
Author(s):  
Shahid Ullah ◽  
Dino Bindi ◽  
Marco Pilz ◽  
Stefano Parolai

<p>It is well known that variability in the surface geology potentially leads to the modification of earthquake-induced ground motion over short distances. Although this effect is of major importance when seismic hazard is assessed at the urban level, it is very often not appropriately accounted for. In this paper, we present a first attempt at taking into account the influence of the shallow geological structure on the seismic hazard assessment for Bishkek, Kyrgyzstan, using a proxy (Vs30) that has been estimated from in situ seismic noise array analyses, and considering response spectral ratios calculated by analyzing a series of earthquake recordings of a temporary seismic network. To highlight the spatial variability of the observed ground motion, the obtained results are compared with those estimated assuming a homogeneous Vs30 value over the whole urban area. The seismic hazard is evaluated in terms of peak ground acceleration (PGA) and spectral acceleration (SA) at different periods (frequencies). The presented results consider the values obtained for a 10% probability of exceedance in 50 years. The largest SA estimated considering a rock site classification of the area (0.43 g) is observed for a period of 0.1 s (10 Hz), while the maximum PGA reaches 0.21 g. When site effects are included through the Vs30 proxy in the seismic hazard calculation, the largest SA, 0.67 g, is obtained for a period of 0.3 s (about 3.3 Hz). In terms of PGA, in this case the largest estimated value reaches 0.31 g in the northern part of the town. When the variability of ground motion is accounted for through response spectrum ratios, the largest SA reaches a value as high as 1.39 g at a period of 0.5 s. In general, considering site effects in the seismic hazard assessment of Bishkek leads to an increase of seismic hazard in the north of the city, which is thus identified as the most hazardous part within the study area and which is more far away from the faults.</p>


2019 ◽  
Vol 55 (1) ◽  
pp. 109 ◽  
Author(s):  
Nikolaos Vavlas ◽  
Anastasia Kiratzi ◽  
Basil Margaris ◽  
George Karakaisis

We carry out a probabilistic seismic hazard assessment (PSHA) for Lesvos Island, in the northeastern Aegean Sea. Being the most populated island in the northern Aegean Sea and hosting the capital of the prefecture, its seismic potential has significant social-economic meaning. For the seismic hazard estimation, the newest version of the R-CRISIS module, which has high efficiency and flexibility in model selection, is used. We incorporate into the calculations eight (8) ground motion prediction equations (GMPEs). The measures used are peak ground acceleration, (PGA), peak ground velocity, (PGV), and spectral acceleration, (SA), at T=0.2 sec representative of the building stock. We calculate hazard curves for selected sites on the island, sampling the southern and northern parts: Mytilene, the capital, the village of Vrisa, Mithymna and Sigri. Hazard maps are also presented in terms of all three intensity measures, for a mean return period of 475 years (or 10% probability of exceedance in 50 years), assuming a Poisson process. Our results are comparable to the predictions of on-going EU hazard models, but higher than the provisions of the Greek Seismic Code. Finally, we perform disaggregation of hazard to depict the relative contribution of different earthquake sources and magnitudes to the results.


2010 ◽  
Vol 10 (1) ◽  
pp. 51-59 ◽  
Author(s):  
G-A. Tselentis ◽  
L. Danciu

Abstract. The present third part of the study, concerning the evaluation of earthquake hazard in Greece in terms of various ground motion parameters, deals with the deaggregation of the obtained results The seismic hazard maps presented for peak ground acceleration and spectral acceleration at 0.2 s and 1.0 s, with 10% probability of exceedance in 50 years, were deaggregated in order to quantify the dominant scenario. There are three basic components of each dominant scenario: earthquake magnitude (M), source-to-site distance (R) and epsilon (ε). We present deaggregation maps of mean and mode values of M-R-ε triplet showing the contribution to hazard over a dense grid.


2020 ◽  
Vol 110 (3) ◽  
pp. 1162-1171
Author(s):  
Hongliu Ran

ABSTRACT Aleatory variability is the natural randomness in a process and can affect probabilistic seismic hazard assessment (PSHA). In this study, considering a simple case of a square areal source zone, I employ Monte Carlo methods to estimate aleatory uncertainties due to random variations in temporal, spatial, and magnitude distribution of seismicity within the zone for PSHA. The results show that (1) uncertainty from aleatory variability in PSHA is significant for areas with low-seismic activity, (2) the ratio of the 85th to 15th percentiles of peak ground acceleration (PGA) decreases as the occurrence rate increases, and (3) accounting for random variations in seismic parameters changes the estimated PGA by more than 10%. My analysis applies to the case in which there are fewer than 10 earthquakes over 50 yr, the site is located outside of the areal source, and b≥1.0. This situation should be considered in PSHA due to the cutoff effect of the magnitude lower limit. In addition, the sensitivity analysis shows that random variations in earthquake magnitude distribution are the largest contributor to aleatory uncertainty in most cases.


2020 ◽  
Vol 1 (2) ◽  
Author(s):  
Cao Dinh Trong ◽  
Xuan-Nam BUI ◽  
Pham NAM HUNG ◽  
Thai ANH TUAN ◽  
Mai XUAN BACH ◽  
...  

This paper presents the seismic hazard assessment for Thuong Tan-Tan My quarries in Di An commune, Binh Duong province, Vietnam. Combination methods of gravity and magneto-telluric were used to estimate the dip angle and the width of the seismic source. The highest water column of 160 m will cause direct stress on the reservoir bottom with a maximum value of 1535.600 kPa and Coulomb stress of 68.693 kPa (at a depth of 2 km). The typical components of natural earthquake hazard (Mn.max = 5.0, depth of 10 km) in Thuong Tan - Tan My reservoir have the following values: peak ground acceleration PGA = 0.073 g ÷ 0.212 g; peak ground velocity PGV = 2.662 cm/s ÷ 7.984 cm/s; peak ground displacement PGD = 0.706 cm ÷ 1.918 cm at 10% probability of exceedance in 50 years. The typical components of triggered earthquake hazard (Mtr.max = 3.5, depth of 6 km) in Thuong Tan - Tan My reservoir have the following values: peak ground acceleration PGA = 0.024 g ÷ 0.172 g; peak ground velocity PGV = 0 ÷ 5.484 cm/s; peak ground displacement PGD = 0.061 cm ÷ 0.461 cm at 10% probability of exceedance in 50 years.


2019 ◽  
Vol 41 (4) ◽  
pp. 321-338
Author(s):  
Pham The Truyen ◽  
Nguyen Hong Phuong

In this study, the methodology of probabilistic seismic hazard assessment proposed by Cornell and Esteva in 1968 was applied for Hanoi city, using an earthquake catalog updated until 2018 and a comprehensive seismotectonic model of the territory of Vietnam and adjacent sea areas. Statistical methods were applied for declustering the earthquake catalog, then the maximum likelihood method was used to estimate the parameters of the Gutenberg–Richter Law and the maximum magnitude for each seismic source zone. Two GMPEs proposed by Campbell & Bozorgnia (2008) and Akkar et al., (2014) were selected for use in hazard analysis. Results of PSHA for Hanoi city are presented in the form of probabilistic seismic hazard maps, depicting peak horizontal ground acceleration (PGA) as well as 5-hertz (0.2 sec period) and 1-hertz (1.0 sec. period) spectral accelerations (SA) with 5-percent damping on a uniform firm rock site condition, with 10%, 5%, 2% and 0,5% probability of exceedance in 50 years, corresponding to return times of 475; 975; 2,475 and 9,975 years, respectively. The results of PSHA show that, for the whole territory of Hanoi city, for all four return periods, the predicted PGA values correspond to the intensity of VII to IX degrees according to the MSK-64 scale. As for the SA maps, for all four return periods, the predicted SA values at 1.0 s period correspond to the intensity of VI to VII, while the predicted SA values at 0.2 s period correspond to the intensity of VIII to X according to the MSK-64 scale. This is the last updated version of the probabilistic seismic hazard maps of Hanoi city. The 2019 probabilistic seismic hazard maps of Hanoi city display earthquake ground motions for various probability levels and can be applied in seismic provisions of building codes, insurance rate structures, risk assessments, and other public policy.


2009 ◽  
Vol 47 (6) ◽  
Author(s):  
T. M. Tsapanos ◽  
P. Mäntyniemi ◽  
A. Kijko

A probabilistic approach was applied to map the seismic hazard in Greece and the surrounding region. The procedure does not require any specification of seismic sources or/and seismic zones and allows for the use of the whole seismological record, comprising both historical and instrumental data, available for the region of interest. The new seismic hazard map prepared for Greece and its vicinity specifies a 10% probability of exceedance of the given Peak Ground Acceleration (PGA) values for shallow seismicity and intermediate soil conditions for an exposure time of 50 years. When preparing the map, the new PGA attenuation relation given by Margaris et al. (2001) was employed. The new map shows a spatial distribution of the seismic hazard that corresponds well with the features of shallow seismicity within the examined region. It depicts the level of seismic hazard in which the exceedance of the PGA value of 0.25 g may be expected to occur within limited areas. The highest estimated levels of seismic hazard inside the territory of Greece are found in the Northern Sporades Islands, where PGA values in excess of 0.50 g are reached at individual sites, and in the Zante Island in Western Greece, where PGA values in the range of 0.35 g to 0.40 g are obtained at more numerous localities. High values are also observed in the sea between the Karpathos and Rhodes islands, near the Island of Amorgos (Cyclades Archipelago) and in the Southwestern Peloponnesus. The levels of seismic hazard at the sites of seven Greek cities (Athens, Jannena, Kalamata, Kozani, Larisa, Rhodes and Thessaloniki) were also estimated in terms of probabilities that a given PGA value will be exceeded at least once during a time interval of 1, 50 and 100 years at those sites. These probabilities were based on the maximum horizontal PGA values obtained by applying the design earthquake procedure, and the respective median values obtained were 0.24 g for Athens, 0.28 g for Jannena, 0.30 g for Kalamata, 0.21 g for Kozani, 0.24 g for Larisa, 0.43 g for Rhodes and 0.35 g for Thessaloniki. The probabilities of exceedance of the estimated maximum possible PGA value were also calculated for the cities to illustrate the uncertainty of maximum PGA assessment.


2009 ◽  
Vol 22 ◽  
pp. 147-153 ◽  
Author(s):  
F. Leyton ◽  
S. Ruiz ◽  
S. A. Sepúlveda

Abstract. Chile is one of the most seismically active countries in the world; indeed, having witnessed very large earthquakes associated with high horizontal peak ground accelerations, the use of probabilistic hazard assessment is an important tool in any decision-making. In the present study, we review all the available information to improve the estimation of the probabilistic seismic hazard caused by two main sources: shallow interplate, thrust earthquakes and intermediate depth, intraplate earthquakes. Using previously defined seismic zones, we compute Gutenberg-Richter laws and, along with appropriate attenuation laws, revaluate the probabilistic seismic hazard assessments in Chile. We obtain expected horizontal peak ground acceleration with a 10% of probability of being exceeded in 50 years, reaching from 0.6 g up 1.0 g in the coast and between 0.4 g and 0.6 g towards the Andes Mountains, with larger values in Northern part of the country. The present study improves our knowledge of geological hazards in Chile, enabling the mitigation of important human and material losses due to large earthquakes in the future.


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