A combined fault- and catalog-based hazard assessment for Central Zagros, Iran

2021 ◽  
Author(s):  
Nima Dolatabadi ◽  
Nasrin Tavakolizadeh ◽  
Hamzeh Mohammadigheymasi ◽  
Alessandro Valentini
Keyword(s):  
Hazard Assessment ◽  
Convergence Rates ◽  
Active Faults ◽  
Distributed Model ◽  
Probabilistic Seismic Hazard Assessment ◽  
Geometrical Parameters ◽  
Earthquake Catalog ◽  
Zagros Mountains ◽  
Aggregated Model ◽  
Distributed Seismicity

<p>The Zagros mountains is a tectonically active Arabian-Eurasian plate convergence zone. The convergence direction changes along the strike of the belt, results in oblique faulting in the North-Western Zagros (NWZ) and the prevalence of pure reverse faulting in the South-Eastern Zagros (SEZ). The two regions undergo different convergence rates, (4 ± 2 mm yr −1) in NWZ and (9 ± 2 mm yr −1) in SEZ. These differences is partially accommodated by right-lateral strike-slip faulting throughout the Central Zagros (CZ), resulting in catastrophic earthquakes like 1972 Mw = 6.7 Qir and 1934 Mw = 6.3 Kazerun. This study presents the Probabilistic Seismic Hazard Assessment (PSHA) for the CZ region by integrating fault sources and seismological data. The seismological catalog data consists of 6504 events (2.5 < Mw < 6.7) during 1925-2020 and was compiled from the International Seismological Center (ISC) and the Iranian Seismological Center (IRSC). The faults with the history of Mw > 5.5 or geometrical potential of producing such an event were modeled. A Truncated Gutenberg–Richter (TGR) Magnitude-Frequency Distribution (MFD) for a range of magnitudes (5.5 < Mw < Mmax ) is evaluated by processing the geometrical parameters and slip rate of each fault source using the FiSH code. The Mmax is computed for each source by combining various Mmax estimates based on the faults geometry and observed Mmax if it is available. The catalog data was modeled as a grid source. A unique set of seismic activity rate parameters (for Mw > 4) in each grid is obtained by applying a modified smoothed seismicity approach. More precisely, a penalized likelihood-based methodwas utilized for the spatial estimation of the b-values, and a weighted smoothing method was implemented to calculate the spatial distribution of the a-values. The catalog events with Mw > 5.5 were excluded to avoid duplicated hazard estimation (modified earthquake catalog). Compiling the source models, the hazard computations were performed using the OpenQuake Engine. The Peak Ground Acceleration (PGA) is computed for the Probability Of Exceedance (POE) of 10% over 50 years for distributed seismicity obtained by the full catalog, and an aggregated model of active faults and distributed seismicity with the modified earthquake catalog. The distributed model produces an approximately uniform PGA with a maximum value of 0.185 g over CZ, while the aggregated model accents the PGA in the vicinity of the faults the maximum of 0.319 g observed around the Kazerun fault. The results show the competence of aggregating fault-based and distributed seismicity hazard assessments for applying comprehensive PSHA studies.</p>

scholarly journals Seismic hazard for the Trans Adriatic Pipeline (TAP). Part 2: broadband scenarios at the Fier Compressor Station (Albania)

2021 ◽  
Author(s):  
L. Moratto ◽  
A. Vuan ◽  
A. Saraò ◽  
D. Slejko ◽  
C. Papazachos ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Hazard Assessment ◽  
Transfer Functions ◽  
Active Faults ◽  
Seismic Hazard Assessment ◽  
Probabilistic Seismic Hazard Assessment ◽  
Compressor Station ◽  
Damage Functions ◽  
Worst Case

AbstractTo ensure environmental and public safety, critical facilities require rigorous seismic hazard analysis to define seismic input for their design. We consider the case of the Trans Adriatic Pipeline (TAP), which is a pipeline that transports natural gas from the Caspian Sea to southern Italy, crossing active faults and areas characterized by high seismicity levels. For this pipeline, we develop a Probabilistic Seismic Hazard Assessment (PSHA) for the broader area, and, for the selected critical sites, we perform deterministic seismic hazard assessment (DSHA), by calculating shaking scenarios that account for the physics of the source, propagation, and site effects. This paper presents a DSHA for a compressor station located at Fier, along the Albanian coastal region. Considering the location of the most hazardous faults in the study site, revealed by the PSHA disaggregation, we model the ground motion for two different scenarios to simulate the worst-case scenario for this compressor station. We compute broadband waveforms for receivers on soft soils by applying specific transfer functions estimated from the available geotechnical data for the Fier area. The simulations reproduce the variability observed in the ground motion recorded in the near-earthquake source. The vertical ground motion is strong for receivers placed above the rupture areas and should not be ignored in seismic designs; furthermore, our vertical simulations reproduce the displacement and the static offset of the ground motion highlighted in recent studies. This observation confirms the importance of the DSHA analysis in defining the expected pipeline damage functions and permanent soil deformations.

Probabilistic Seismic Hazard Assessment Using Legacy Data in Georgia

2020 ◽  
Vol 91 (3) ◽  
pp. 1500-1517 ◽  
Author(s):  
Tuna Onur ◽  
Rengin Gok ◽  
Tea Godoladze ◽  
Irakli Gunia ◽  
Giorgi Boichenko ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Hazard Assessment ◽  
Data Exchange ◽  
Seismic Hazard Assessment ◽  
Probabilistic Seismic Hazard Assessment ◽  
Probabilistic Seismic Hazard ◽  
Earthquake Catalog ◽  
The Caucasus ◽  
New Locations ◽  
Legacy Data

Abstract The Caucasus has a documented history of cataloging earthquakes stretching back to the beginning of the Christian era. Instrumental seismic observation in the Caucasus began in 1899, when the first seismograph was installed in Tbilisi, Georgia. During the Soviet era (1921–1991 in Georgia), the number of seismic stations increased in the region, providing better network coverage and a valuable dataset for seismic research. Data from many thousands of earthquakes recorded by this regional network was stored on paper in seismic bulletins. As part of the project outlined in this article, we pulled together and digitized all available paper bulletins from Georgia and neighboring countries. This allowed significant Limprovements in location accuracy and recalculation of more robust moment magnitudes for earthquakes in this region. It also paved the way for future collaboration and data exchange among the countries in the Caucasus. The resulting earthquake catalog with the new locations and magnitudes was used to conduct a probabilistic seismic hazard assessment to support a major update to the building code in Georgia to align it with the European codes. This article outlines the improvements made to the earthquake catalog in Georgia using legacy data and the new hazard assessment based on this improved dataset.

scholarly journals Methodology for earthquake rupture rate estimates of fault networks: example for the western Corinth rift, Greece

2017 ◽  
Vol 17 (10) ◽  
pp. 1857-1869 ◽  
Author(s):  
Thomas Chartier ◽  
Oona Scotti ◽  
Hélène Lyon-Caen ◽  
Aurélien Boiselet
Keyword(s):  
Active Faults ◽  
Seismic Hazard Assessment ◽  
System Level ◽  
Fault System ◽  
Normal Faults ◽  
Accurate Estimation ◽  
Probabilistic Seismic Hazard Assessment ◽  
Earthquake Catalog ◽  
Earthquake Rupture ◽  
Multiple Faults

Abstract. Modeling the seismic potential of active faults is a fundamental step of probabilistic seismic hazard assessment (PSHA). An accurate estimation of the rate of earthquakes on the faults is necessary in order to obtain the probability of exceedance of a given ground motion. Most PSHA studies consider faults as independent structures and neglect the possibility of multiple faults or fault segments rupturing simultaneously (fault-to-fault, FtF, ruptures). The Uniform California Earthquake Rupture Forecast version 3 (UCERF-3) model takes into account this possibility by considering a system-level approach rather than an individual-fault-level approach using the geological, seismological and geodetical information to invert the earthquake rates. In many places of the world seismological and geodetical information along fault networks is often not well constrained. There is therefore a need to propose a methodology relying on geological information alone to compute earthquake rates of the faults in the network. In the proposed methodology, a simple distance criteria is used to define FtF ruptures and consider single faults or FtF ruptures as an aleatory uncertainty, similarly to UCERF-3. Rates of earthquakes on faults are then computed following two constraints: the magnitude frequency distribution (MFD) of earthquakes in the fault system as a whole must follow an a priori chosen shape and the rate of earthquakes on each fault is determined by the specific slip rate of each segment depending on the possible FtF ruptures. The modeled earthquake rates are then compared to the available independent data (geodetical, seismological and paleoseismological data) in order to weight different hypothesis explored in a logic tree.The methodology is tested on the western Corinth rift (WCR), Greece, where recent advancements have been made in the understanding of the geological slip rates of the complex network of normal faults which are accommodating the ∼ 15 mm yr−1 north–south extension. Modeling results show that geological, seismological and paleoseismological rates of earthquakes cannot be reconciled with only single-fault-rupture scenarios and require hypothesizing a large spectrum of possible FtF rupture sets. In order to fit the imposed regional Gutenberg–Richter (GR) MFD target, some of the slip along certain faults needs to be accommodated either with interseismic creep or as post-seismic processes. Furthermore, computed individual faults' MFDs differ depending on the position of each fault in the system and the possible FtF ruptures associated with the fault. Finally, a comparison of modeled earthquake rupture rates with those deduced from the regional and local earthquake catalog statistics and local paleoseismological data indicates a better fit with the FtF rupture set constructed with a distance criteria based on 5 km rather than 3 km, suggesting a high connectivity of faults in the WCR fault system.

scholarly journals Probabilistic Seismic Hazard Assessment for United Arab Emirates, Qatar and Bahrain

2020 ◽  
Vol 10 (21) ◽  
pp. 7901
Author(s):  
Rashad Sawires ◽  
José A. Peláez ◽  
Mohamed Hamdache
Keyword(s):  
Seismic Hazard ◽  
United Arab Emirates ◽  
Hazard Assessment ◽  
Return Period ◽  
Seismic Hazard Assessment ◽  
Probabilistic Seismic Hazard Assessment ◽  
Probabilistic Seismic Hazard ◽  
Earthquake Catalog ◽  
Intermediate Depth ◽  
Seismic Source Models

A probabilistic seismic hazard assessment in terms of peak ground acceleration (PGA) and spectral acceleration (SA) values, for both 10% and 5% probability of exceedance in 50 years, has been performed for the United Arab Emirates, Qatar, and Bahrain. To do that, an updated, unified, and Poissonian earthquake catalog (since 685 to 2019) was prepared for this work. Three alternative seismic source models were considered in a designed logic-tree framework. The discrimination between the shallow and intermediate depth seismicity along the Zagros and the Makran regions was also considered in this assessment. Three alternative ground-motion attenuation models for crustal earthquakes and one additional for intermediate-depth ones have been selected and applied in this study, considering the predominant stress regime computed previously for each defined source. This assessment highlights that the maximum obtained hazard values are observed in the northeastern part of the studied region, specifically at Ras Al-Khaimah, Umm Al-Quwain, and Fujaira, being characterized by mean PGA and SA (0.2 s) pair values equal to (0.13 g, 0.30 g), (0.12 g, 0.29 g), and (0.13 g, 0.28 g), respectively, for a 475-year return period and for B/C National Earthquake Hazards Reduction Program (NEHRP) boundary site conditions. Seismic hazard deaggregation in terms of magnitude and distance was also computed for a return period of 475 years, for ten emirates and cities, and for four different spectral periods.

scholarly journals Probabilistic seismic hazard assessment for Hanoi city

2019 ◽  
Vol 41 (4) ◽  
pp. 321-338
Author(s):  
Pham The Truyen ◽  
Nguyen Hong Phuong
Keyword(s):  
Seismic Hazard ◽  
Hazard Assessment ◽  
Seismic Hazard Assessment ◽  
Probabilistic Seismic Hazard Assessment ◽  
Probabilistic Seismic Hazard ◽  
Earthquake Catalog ◽  
Return Periods ◽  
Hazard Maps ◽  
Seismic Hazard Maps ◽  
S Period

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.

scholarly journals Probabilistic seismic hazard assessment of the Canterbury region, New Zealand

2001 ◽  
Vol 34 (4) ◽  
pp. 318-334 ◽  
Author(s):  
Mark Stirling ◽  
Jarg Pettinga ◽  
Kelvin Berryman ◽  
Mark Yetton
Keyword(s):  
New Zealand ◽  
Seismic Hazard ◽  
Hazard Assessment ◽  
Regional Scale ◽  
Active Faults ◽  
Seismic Hazard Assessment ◽  
Historical Seismicity ◽  
Probabilistic Seismic Hazard Assessment ◽  
Probabilistic Seismic Hazard ◽  
Ground Acceleration

We present the main results of a probabilistic seismic hazard assessment of the Canterbury region recently completed for Environment Canterbury (formerly Canterbury Regional Council). We use the distribution of active faults and the historical record of earthquakes to estimate the levels of earthquake shaking (peak ground acceleration and response spectral accelerations) that can be expected across the Canterbury region with return periods of 150, 475 and 1000 years. The strongest shaking (e.g. 475 year peak ground accelerations of 0.7g or more) can be expected in the west and north to northwest of the Canterbury region, where the greatest concentrations of known active faults and historical seismicity are located. Site-specific analyses of eight towns and cities selected by Environment Canterbury show that Arthur's Pass and Kaikoura are located within these zones of high hazard. In contrast, the centres studied in the Canterbury Plains (Rangiora, Kaiapoi, Christchurch, Ashburton, Temuka and Timaru) are generally located away from the zones of highest hazard. The study represents the first application of recently-developed methods in probabilistic seismic hazard at a regional scale in New Zealand.

Probabilistic seismic hazard assessment for the main cities along the continental section of the Cameroon volcanic line

2021 ◽  
Vol 14 (9) ◽  
Author(s):  
Etoundi Delair Dieudonné Ndibi ◽  
Eddy Ferdinand Mbossi ◽  
Nguet Pauline Wokwenmendam ◽  
Bekoa Ateba ◽  
Théophile Ndougsa-Mbarga
Keyword(s):  
Seismic Hazard ◽  
Hazard Assessment ◽  
Seismic Hazard Assessment ◽  
Probabilistic Seismic Hazard Assessment ◽  
Probabilistic Seismic Hazard ◽  
Cameroon Volcanic Line
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