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 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.

Seismic hazard estimate from background seismicity in southern California

1996 ◽  
Vol 86 (5) ◽  
pp. 1372-1381 ◽  
Author(s):  
Tianqing Cao ◽  
Mark D. Petersen ◽  
Michael S. Reichle
Keyword(s):  
Seismic Hazard ◽  
Southern California ◽  
Seismic Source ◽  
Source Model ◽  
Historical Seismicity ◽  
Rational Approach ◽  
Smoothing Function ◽  
Background Seismicity ◽  
Seismic Source Model ◽  
Seismicity Catalog

Abstract We analyzed the historical seismicity in southern California to develop a rational approach for calculating the seismic hazard from background seismicity of magnitude 6.5 or smaller. The basic assumption for the approach is that future earthquakes will be clustered spatially near locations of historical mainshocks of magnitudes equal to or greater than 4. We analyzed the declustered California seismicity catalog to compute the rate of earthquakes on a grid and then smoothed these rates to account for the spatial distribution of future earthquakes. To find a suitable spatial smoothing function, we studied the distance (r) correlation for southern California earthquakes and found that they follow a 1/rµ power-law relation, where µ increases with magnitude. This result suggests that larger events are more clustered in space than smaller earthquakes. Assuming the seismicity follows the Gutenberg-Richter distribution, we calculated peak ground accelerations (PGA) for 10% probability of exceedance in 50 yr. PGA estimates range between 0.25 and 0.35 g across much of southern California. These ground-motion levels are generally less than half the levels of hazard that are obtained using the entire seismic source model that also includes geologic and geodetic data. We also calculated the overall uncertainty for the hazard map using a Monte Carlo method and found that the coefficient of variation is about 0.24 ± 0.01 for much of the region.

Identifying the main factors that control Probabilistic Seismic Hazard Assessment (PSHA) in the Aegean area: Results from OFAT (One Factor at A Time) analysis

2021 ◽  
Author(s):  
Athanasia Kerkenou ◽  
Constantinos Papazachos ◽  
Basil Margaris ◽  
Christos Papaioannou
Keyword(s):  
Seismic Hazard ◽  
Seismic Hazard Assessment ◽  
Seismic Source ◽  
Source Model ◽  
Probabilistic Seismic Hazard Assessment ◽  
Critical Factors ◽  
Time Analysis ◽  
Aegean Area ◽  
Seismicity Parameters ◽  
Main Factors

<p>The broader Aegean area is one of the highest seismicity regions in Europe, with almost half of the European seismicity released in this region, often with damaging mainshocks, such as the recent <strong>M</strong>7.0 Samos event. While several Probabilistic Seismic Hazard Assessment (PSHA) studies have been performed for this area, an attempt to quantify the main factors controlling PSHA has not been performed. To study the effect that each input factor (seismic source model, GMPE, seismicity parameters, etc.) has on the seismic hazard calculations, an <strong>OFAT</strong> (One Factor at A Time) analysis has been conducted. For this analysis we considered two standard peak ground motion parameters, PGA and PGV, for a typical PSHA scenario, namely 10% probability of exceedance for a mean return period of 50 years (equivalent to a 476 yr return period). For the analysis the following factors were considered: a) Four (4) seismicity area-type source models for the broader Aegean area (Papazachos, 1990; Papaioannou and Papazachos, 2000; Woessner et al., 2015; Vamvakaris et al., 2016), as well as various uncertainties for the associated G-R seismicity parameters and active fault geometries of each seismic source, b) ten (10) Ground Motion Prediction Equations (GMPEs), which contain four NGA-West2 (Abrahamson et al., 2014; Boore et al., 2014; Campbell and Bozorgnia, 2014; Chiou and Youngs, 2014), two European (Bindi et al., 2011; Cauzzi and Faccioli, 2008) and four “Greek” (Theodulidis and Papazachos, 1992; Skarlatoudis et al., 2003; Danciu and Tselentis, 2007; Chousianitis et al., 2018) equations, as well as a variable number of sigma for each equation and, c) the minimum (Mmin) and maximum (Mmax) source magnitude of each seismic source. Tornado diagrams (Howard, 1988) were generated for 42 selected sites of seismological interest that span the study area, allowing to explore the extent of each factor’s effect on the PSHA results. The sensitivity analysis results suggest that the GMPE selection, as well as uncertainties in the G-R parameters <strong>a</strong> and <strong>b</strong> are the most critical factors, significantly affecting the PGA/PGV levels for all sites. They also reveal a strong correlation of PSHA sensitivity with other seismicity parameters. For example, the employed source model and Mmax play a more critical role for regions of low seismicity, while the least important factor is the selected Mmin. The spatial distribution of the PSHA sensitivity on the various factors considered was also examined through the generation of several maps, exposing regions of high and of low PSHA uncertainty. The results can be efficiently employed by scientists and engineers in order to focus research and application efforts for a targeted uncertainty minimization of the most critical factors (which may not be the same for all sub-regions of the examined Aegean area), as well as to evaluate the reliability and uncertainty of the current PSHA estimates that are employed in seismic design.</p>

Delineation and characterization of a new seismic source model for seismic hazard studies in Egypt

2015 ◽  
Vol 80 (3) ◽  
pp. 1823-1864 ◽  
Author(s):  
R. Sawires ◽  
J. A. Peláez ◽  
H. A. Ibrahim ◽  
R. E. Fat-Helbary ◽  
J. Henares ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Seismic Source ◽  
Source Model ◽  
Seismic Source Model

scholarly journals Probabilistic seismic hazard maps for the North Balkan region

1999 ◽  
Vol 42 (6) ◽  
Author(s):  
R. M. W. Musson
Keyword(s):  
Seismic Hazard ◽  
Seismic Source ◽  
Source Model ◽  
Seismic Zone ◽  
Hazard Maps ◽  
Large Area ◽  
Ground Acceleration ◽  
Seismic Hazard Maps ◽  
The North ◽  
Seismic Source Model

A set of seismic hazard maps, expressed as horizontal peak ground acceleration, have been computed for a large area of Central and Eastern Europe covering the North Balkan area (Former Yugoslavia, Hungary, Romania). These are based on: a) a compound earthquake catalogue for the region; b) a seismic source model of 50 zones compiled on the basis of tectonic divisions and seismicity, and c) a probabilistic methodology using stochastic (Monte Carlo) modelling. It is found that the highest hazard in the region comes from intermediate focus earthquakes occurring in the Vrancea seismic zone; here the hazard exceeds 0.4 g at return periods of 475 years. Special account has been taken of the directional nature of attenuation from this source.

Seismic source model for moving vehicles

2005 ◽  
Vol 43 (2) ◽  
pp. 248-256 ◽  
Author(s):  
S.A. Ketcham ◽  
M.L. Moran ◽  
J. Lacombe ◽  
R.J. Greenfield ◽  
T.S. Anderson
Keyword(s):  
Seismic Source ◽  
Source Model ◽  
Moving Vehicles ◽  
Seismic Source Model

On the Nature of Logic Trees in Probabilistic Seismic Hazard Assessment

2012 ◽  
Vol 28 (3) ◽  
pp. 1291-1296 ◽  
Author(s):  
Roger Musson
Keyword(s):  
Seismic Hazard Assessment ◽  
Seismic Source ◽  
Source Model ◽  
Probabilistic Seismic Hazard Assessment ◽  
Motion Model ◽  
Logic Tree ◽  
Ground Motion Model ◽  
Seismic Source Model ◽  
Kolmogorov Axioms ◽  
Better Than

An objection sometimes made against treating the weights of logic tree branches as probabilities relates to the Kolmogorov axioms, but these are only an obstacle if one believes that logic tree branches represent a seismic source model or ground motion model as being “true.” Models are never true, but some models are better than others. It is argued here that a logic tree weight represents the probability that the model in question is better than the others considered. Only one branch can be the best one, and one branch must be the best one. It is also argued that there are situations in PSHA where uncertainty exists but the analyst lacks the means to express it. Therefore it is not necessarily the case that more information increases uncertainty; it may be that more information increases the possibility of expressing uncertainty that was previously unmanageable.

Developing a seismic source model for the Arabian Plate

2018 ◽  
Vol 11 (15) ◽  
Author(s):  
I. El-Hussain ◽  
Y. Al-Shijbi ◽  
A. Deif ◽  
A. M. E. Mohamed ◽  
M. Ezzelarab
Keyword(s):  
Seismic Source ◽  
Source Model ◽  
Arabian Plate ◽  
Seismic Source Model
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