A comparative seismic hazard study for Azerbaijan Province in Iran

1981 ◽  
Vol 71 (1) ◽  
pp. 335-362
Author(s):  
B. Rowshandel ◽  
S. Nemat-Nasser ◽  
R. B. Corotis
Keyword(s):  
Seismic Hazard ◽  
Point Source ◽  
Ground Motion ◽  
Line Source ◽  
Seismic Source ◽  
Source Model ◽  
Strike Slip ◽  
Area Source ◽  
Area Source Model ◽  
Line Source Model

abstract Different seismic source models are used to estimate regional seismic hazard. Commonly used point, line, and area seismic sources are considered in addition to a new method which is obtained by modifying the line source model to take into account the uncertainty associated with the exact location of the line (i.e., fault). The results are presented in terms of cumulative functions of peak ground acceleration for major sites in the Azerbaijan Province of northwest Iran. Iso-acceleration maps for two different return periods are also developed for each seismic source model and a comparison is made among the results of the models. The point source model is shown to be unrealistic when used to model large shocks (Ms > 6.5), which correspond to long ruptures. The model cannot incorporate the fault length, thus ignoring possible spatial migration of seismicity along the fault. In addition, the actual attenuation of ground motion departs considerably from that associated with point source assumption. The conventional line source model, while providing a good representation of vertical strike-slip faults, cannot accurately model the seismicity in other cases, such as reverse faults in general, and thrust (low angle reverse) faults in particular. Epicenters for these latter cases do not lie along a line, as they do in case of vertical strike-slip faults. The area source model is used for those cases where the distribution of earthquake epicenters in a region does not follow any identifiable geological fault pattern. The spatial migration of seismicity along an active fault during a given exposure time is of vital importance in seismic hazard analysis. An analysis based on an area source model corresponds to assuming this migration will be equal in all directions. The theory of plate tectonics, however, suggests an elongated narrow zone corresponding to each fault. A fault line model is developed which exhibits less sensitivity of near-field ground motion to precise fault location than the line source model. This model is referred to as the strip source model. According to this model, the seismicity on a fault is spatially distributed in a long and narrow zone along the margins of the corresponding plates or microplates, and decreases with distance from the fault on either side. It is believed that this kind of modeling closely represents the seismicity corresponding to interplate earthquakes, especially when the type of faulting is thrust. Uncertainties due to the location and orientation of faults will be considerable, particularly for the buried faults, and these uncertainties can be incorporated in the strip source model.

Seismogenic source model of the 2019 Mw 5.9 East-Azerbaijan earthquake (NW Iran) through Sentinel-1 DInSAR measurements

2020 ◽  
Author(s):  
Emanuela Valerio ◽  
Francesco Casu ◽  
Vincenzo Convertito ◽  
Claudio De Luca ◽  
Vincenzo De Novellis ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Seismic Source ◽  
Source Model ◽  
Fault Model ◽  
Strike Slip ◽  
Coseismic Deformation ◽  
Lateral Strike Slip ◽  
Nw Iran ◽  
Seismogenic Source ◽  
East Azerbaijan

<p>On 7 November 2019 (22:47 UTC) a M<sub>w</sub> 5.9 earthquake struck the East-Azerbaijan region, in the north-western Iran, about 100 km east of Tabriz, the fourth largest city of Iran with a population of over two million. This seismic event caused both widespread damage to the surrounding villages and casualties, killing about 5 people and injuring hundreds. The occurrence of this earthquake is related to the main geodynamic regime controlled by the oblique Arabia-Eurasia convergence and, in particular, this event is inserted in the tectonic context of the East-Azerbaijan Plateau, a complex mountain belt that contains internal major fold-and-thrust belts.</p><p>In this work, we first generate the coseismic deformation maps by applying the Differential Synthetic Aperture Radar Interferometry (DInSAR) technique to SAR data collected along ascending and descending orbits by the Sentinel-1 constellation of the European Copernicus Programme. Then, we invert them through analytical modeling in order to better constrain the geometry and characteristics of the main source. The retrieved fault model revealed a shallow seismic source approximately NE–SW-striking and characterized by a left-lateral strike-slip, southeast-dipping faulting mechanism. Our retrieved solution reveals a new minor fault never mapped in geological maps before, whose kinematics is compatible with that of the surrounding structures and with the local and regional stress states. Moreover, we also use the preferred fault model to calculate the Coulomb Failure Function at the nearby receiver faults; taking into account the surrounding geological structures reported in literature, we show that all the considered receiver faults have been positively stressed by the main event. This is also confirmed by the distribution of the aftershocks that occurred near the considered faults. The analysis of the earthquake nucleated along these left-lateral strike-slip minor fault is essential to improve our knowledge of the East-Azerbaijan Plateau; therefore, further studies are required to evaluate their role in seismic hazard definition of northwest of Iran, in order to help in the mitigation of the seismic hazard in seismogenic regions unprepared for the occurrence of seismic events.</p><p><em>This work is supported by: the 2019-2021 IREA-CNR and Italian Civil Protection Department agreement, H2020 EPOS-SP (GA 871121), ENVRI-FAIR (GA 824068) projects, and the I-AMICA (PONa3_00363) project.</em></p>

A probabilistic seismic hazard assessment for the Turkish territory—part I: the area source model

2016 ◽  
Vol 16 (8) ◽  
pp. 3367-3397 ◽  
Author(s):  
Karin Sesetyan ◽  
Mine B. Demircioglu ◽  
Tamer Y. Duman ◽  
Tolga Çan ◽  
Senem Tekin ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Hazard Assessment ◽  
Seismic Hazard Assessment ◽  
Source Model ◽  
Probabilistic Seismic Hazard Assessment ◽  
Probabilistic Seismic Hazard ◽  
Area Source ◽  
Area Source Model

Development and characterization of a seismic source model for the Jalisco-Colima-Michoacán region, Western Mexico

2021 ◽  
Author(s):  
José A. Peláez ◽  
Rashad Sawires ◽  
Miguel A. Santoyo ◽  
Jesús Henares
Keyword(s):  
Seismic Hazard ◽  
Gulf Of California ◽  
Seismic Source ◽  
B Value ◽  
Source Model ◽  
Spreading Center ◽  
Stress Regime ◽  
Area Source ◽  
Seismicity Parameters ◽  
Seismic Source Model

<p>The Mexican subduction zone, the Gulf of California spreading center, as well as the triple junction point around the Jalisco and the Michoacán Blocks, represents the most active seismogenic belts inducing seismic hazard in the Jalisco-Colima-Michoacán region. Herein, considering such seismotectonic setting, we have developed a new seismic source model for the surrounding of this zone to be used as an input to the assessment of the seismic hazard of the region.</p><p>This new model is based on revised Poissonian earthquake (1787-2018) and focal mechanism (1963-2015) catalogs, as well as crustal thickness data and all information about the geometry of the subducting slabs. The proposed model consists of a total of 37 area sources, comprising the three different possible categories of seismicity: shallow crustal, interface subduction, and inslab earthquakes. A special care was taken during the delimitation of the boundaries for each area source to ensure that they represent a relatively homogeneous seismotectonic region, and to include a relatively large number of earthquakes that enable us to compute, as reliable as possible, seismicity parameters.</p><p>Actually, the sources zones were delimited following the standard criteria of assessing a probabilistic seismic hazard, being characterized in terms of their seismicity parameters (annual rate of earthquakes above Mw 4.0, b-value, and maximum expected magnitude), mean seismogenic depth, as well as the predominant stress regime. The proposed seismic source model defines and characterizes regionalized potential seismic sources that can contribute to the seismic hazard at the Jalisco-Colima-Michoacán region, providing the necessary information for seismic hazard estimates.</p>

A theoretical study of the radiation from small strikeslip earthquakes at close distances

1983 ◽  
Vol 73 (1) ◽  
pp. 83-96 ◽  
Author(s):  
Michel Campillo ◽  
Michel Bouchon
Keyword(s):  
Ground Motion ◽  
Epicentral Distance ◽  
Homogeneous Medium ◽  
Source Model ◽  
Strike Slip ◽  
Peak Ground Velocity ◽  
Corner Frequency ◽  
Crack Model ◽  
Sharp Change ◽  
S Wave

abstract We present a study of the seismic radiation of a physically realistic source model—the circular crack model of Madariaga—at close distance range and for vertically heterogeneous crustal structures. We use this model to represent the source of small strike-slip earthquakes. We show that the characteristics of the radiated seismic spectra, like the corner frequency, are strongly affected by the presence of the free surface and by crustal layering, and that they can be considerably different from the ones of the homogeneous-medium far-field solution. The vertical and radial displacement spectra are the most strongly affected. We use this source model to calculate the decay of peak ground velocity with epicentral distance and source depth for small strike-slip earthquakes in California. For distances between 10 and 80 km, the peak horizontal velocity decay is of the form r−1.25 for a 4-km hypocentral depth and r−1.65 for deeper sources. The predominance of supercritically reflected arrivals beyond epicentral distances of 70 to 80 km produces a sharp change in the rate of decay of the ground motion. For most of the cases considered, the peak ground velocity increases between 80 and 100 km. We also show that the S-wave velocity in the source layer is the lower limit of phase velocities associated with significant ground motion.

PSHA of the southern Pacific Islands

2020 ◽  
Author(s):  
K L Johnson ◽  
M Pagani ◽  
R H Styron
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Subduction Zones ◽  
Pacific Islands ◽  
Source Model ◽  
Occurrence Rate ◽  
Probabilistic Seismic Hazard ◽  
Maximum Magnitude ◽  
Probability Of Exceedance ◽  
Magnitude Scaling

Summary The southern Pacific Islands region is highly seismically active, and includes earthquakes from four major subduction systems, seafloor fracture zones and transform faults, and other sources of crustal seismicity. Since 1900, the area has experienced >350 earthquakes of M > 7.0, including 11 of M ≥ 8.0. Given the elevated threat of earthquakes, several probabilistic seismic hazard analyses have been published for this region or encompassed subregions; however, those that are publicly accessible do not provide complete coverage of the region using homogeneous methodologies. Here, we present a probabilistic seismic hazard model for the southern Pacific Islands that comprehensively covers the Solomon Islands in the northwest to the Tonga islands in the southeast. The seismic source model accounts for active shallow crustal seismicity with seafloor faults and gridded smoothed seismicity, subduction interfaces using faults with geometries defined based on geophysical datasets and models, and intraslab seismicity modelled by a set of ruptures that occupy the slab volume. Each source type is assigned occurrence rates based on sub-catalogues classified to each respective tectonic context. Subduction interface and crustal fault occurrence rates also incorporate a tectonic component based on their respective characteristic earthquakes. We demonstrate the use of non-standard magnitude-frequency distributions to reproduce the observed occurrence rates. For subduction interface sources, we use various versions of the source model to account for epistemic uncertainty in factors impacting the maximum magnitude earthquake permissible by each source, varying the interface lower depth and segmentation as well as the magnitude scaling relationship used to compute the maximum magnitude earthquake and subsequently its occurrence rate. The ground motion characterisation uses a logic tree that weights three ground motion prediction equations for each tectonic region. We compute hazard maps for 10% and 2% probability of exceedance in 50 years on rock sites, discussing the regional distribution of peak ground acceleration and spectral acceleration with a period of 1.0 s, honing in on the hazard curves and uniform hazard spectra of several capital or populous cities and drawing comparisons to other recent hazard models. The results reveal that the most hazardous landmasses are the island chains closest to subduction trenches, as well as localised areas with high rates of seismicity occurring in active shallow crust. We use seismic hazard disaggregation to demonstrate that at selected cities located above subduction zones, the PGA with 10% probability of exceedance in 50 years is controlled by Mw > 7.0 subduction interface and intraslab earthquakes, while at cities far from subduction zones, Mw < 6.5 crustal earthquakes contribute most. The model is used for southern Pacific Islands coverage in the Global Earthquake Model Global Hazard Mosaic.

scholarly journals Seismic hazard maps of Peshawar District for various return periods

2020 ◽  
Vol 20 (6) ◽  
pp. 1639-1661
Author(s):  
Khalid Mahmood ◽  
Naveed Ahmad ◽  
Usman Khan ◽  
Qaiser Iqbal
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Target Location ◽  
Epistemic Uncertainty ◽  
Hazard Analysis ◽  
Source Parameters ◽  
Seismic Source ◽  
Return Periods ◽  
Hazard Maps ◽  
Seismic Hazard Maps

Abstract. Probabilistic seismic hazard analysis of Peshawar District has been performed for a grid size of 0.01∘. The seismic sources for the target location are defined as the area polygon with uniform seismicity. The earthquake catalogue was developed based on the earthquake data obtained from different worldwide seismological networks and historical records. The earthquake events obtained at different magnitude scales were converted into moment magnitude using indigenous catalogue-specific regression relationships. The homogenized catalogue was subdivided into shallow crustal and deep-subduction-zone earthquake events. The seismic source parameters were obtained using the bounded Gutenberg–Richter recurrence law. Seismic hazard maps were prepared for peak horizontal acceleration at bedrock level using different ground motion attenuation relationships. The study revealed the selection of an appropriate ground motion prediction equation is crucial for defining the seismic hazard of Peshawar District. The inclusion of deep subduction earthquakes does not add significantly to the seismic hazard for design base ground motions. The seismic hazard map developed for shallow crustal earthquakes, including also the epistemic uncertainty, was in close agreement with the map given in the Building Code of Pakistan Seismic Provisions (2007) for a return period of 475 years on bedrock. The seismic hazard maps for other return periods i.e., 50, 100, 250, 475 and 2500 years, are also presented.

scholarly journals Seismic hazard maps of Peshawar district for various return periods

2019 ◽  
Author(s):  
Khalid Mahmood ◽  
Usman Khan ◽  
Qaiser Iqbal ◽  
Naveed Ahmad
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Target Location ◽  
Epistemic Uncertainty ◽  
Source Parameters ◽  
Seismic Source ◽  
Return Periods ◽  
Hazard Maps ◽  
Earthquake Catalogues ◽  
Seismic Hazard Maps

Abstract. The probabilistic seismic hazard analysis of Peshawar District has been conducted in for a grid size of 0.01. The seismic sources for the target location are defined as the area polygon with uniform seismicity for which, the earthquake catalogues were obtained from different worldwide seismological network data. The earthquake catalogues obtained in different magnitude scale was converted into moment magnitude using regression analysis. The homogenized catalogue was then further subdivided into shallow crustal and deep subduction zone earthquake events for which, the seismic source parameters were obtained using Bounded Gutenberg-Richter Recurrence law. The seismic hazard maps were prepared in term of PGA at bedrock using the different ground motion attenuation relationships. The study shows that; the selection of appropriate ground motion prediction equation is an important factor in deciding the seismic hazard of Peshawar District. The inclusion of deep subduction earthquake does not add significantly to the seismic hazard. The calculated seismic hazard map for shallow crustal earthquake after including the epistemic uncertainty was in close agreement to that developed by BCP-2007 for a return period of 475 years on bedrock. The seismic hazard maps for other return periods i.e., 50, 100, 250, 475 and 2500 years were then prepared.

Sign in / Sign up

Export Citation Format

Share Document