The Varzaghan–Ahar, Iran, Earthquake Doublet (Mw6.4, 6.2): implications for the geodynamics of northwest Iran

Ghods, Abdolreza; Shabanian, Esmaeil; Bergman, Eric; Faridi, Mohammad; Donner, Stefanie; Mortezanejad, Gholamreza; Aziz-Zanjani, Asiyeh

doi:10.1093/gji/ggv306

Cited by 59 publications

(60 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We run ∆CFS calculation due to the first shock with an introduced cushion slip model. The result coincides with positive ∆CFS for northsouth nodal plane (CMT solution) for the second large shock at its hypocenter location given by Ghods et al (2015). In contrary, we observe negative ∆CFS for eastwest strike-slip focal mechanism at this place.…”

Section: Discussionsupporting

confidence: 86%

“…In this study we also tried to characterize a new source model mainly based on field measurements and geomorphological observations by Ghods et al (2015). The constructed source model with five 14 km vertically dipped segments makes a fault with 19 km length along east-west orientation (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…First Shock: Concluding from the active faulting map that Ghods et al (2015) provide together with the rupture alignments the faulting strike is divided into five vertical segments (Fig. 6).…”

Section: Assessing the Source Model For The Doubletmentioning

confidence: 99%

See 2 more Smart Citations

Stress Transfere and Statistical Analysis of 2012 Ahar-Varzeghan Seismic Sequnce, Northwestern Iran

Yazdi¹,

Escribano²,

Santoyo³

2017

Proceedings - 1st Congress in Geomatics Engineering - CIGeo

View full text Add to dashboard Cite

Abstract:In 11 of August 2012, two destructive earthquakes with Mw= 6.4 and 6.2 occurred between cities Ahar and Varzeghan (Northwest Iran). They had a close epicentral distance of 6 Km and also had a short time lag of 11 minutes. Following that, a high-rate of aftershock activity began where during the first month more than 2000 events (M≥0.7) affected several villages in the area. The seismic released energy induced significant damage and losses in an extensive zone. Right after the seismic doublet occurrence, a surface rupture with a primarily east-west orientation was observed. The idea of having an almost vertically dipped fault plane for the first shock is more consistent with the trace of the upper edge on the surface and the focal mechanism solutions which propose a steady dipping EW. Previous studies propose different geometries for the generating faults of the second earthquake. In this study, we associate the surface rupture with the first mainshock and both nodal plane explaining the relationship between the two main seismic events are discussed after Coulomb failure stress calculation due to the first shock. Then the stress transfer because of the doublet is analyzed in order to determine its consistency with the statistical modeling prediction for the aftershock population and spatial distribution. For statistical modeling a temporal version of Epidemic Type Aftershock Sequence (ETAS) is applied on one-year seismicity including events with minimum magnitude of 2.5. Key words: Statistical Seismology, ETAS, Coulomb Failure stress, IRAN Resumen:Dos terremotos destructivos, de magnitudes Mw=6.4 y 6.2, ocurrieron el 11 de agosto de 2012 entre las ciudades iraníes de Ahar y Varzeghan. Los epicentros se situaron cerca entre sí, a una distancia de 6 km, y con un intervalo temporal de 11 muinutos. La serie de réplicas subsiguiente se desarrollo con una tasa alta, de más de 2000 eventos en el primer mes (M≥0.7). El movimiento sísmico produjo considerable daño y pérdidas en una zona extensa. El primer evento causó una ruptura semi-vertical, consistente con uno de los planos nodales del mecanismo focal y con una ruptura en superficie con orientación este-oeste. En cuanta a la falla causante del segundo evento principal, existen varias hipótesis. En este trabajo se realiza un modelo de transferencia de esfuerzos estáticos de Coulomb debidos al primer evento para delimitar las zonas cargadas de esfuerzos en las que es más plausible que se haya desencadenado el segundo evento principal. Seguidamente, se considera el cambio de esfuerzos producido por los dos eventos a fin de determinar cuales son las zonas cargadas positiva y negativamente de esfuerzos. De forma complementaria, se desarrolla un modelado estadístico de la población de réplicas y su distribución espacial. Se usa la versión temporal del modelo ETAS (Epidemic Type Aftreshock Sequence) para identificar los eventos que son réplicas y se analiza su distribución espacial en relación a la distribución de los incrementos / decrementos de esfuerzos de Coulom...

show abstract

Section: Discussionsupporting

confidence: 86%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Stress Transfere and Statistical Analysis of 2012 Ahar-Varzeghan Seismic Sequnce, Northwestern Iran

Yazdi¹,

Escribano²,

Santoyo³

2017

Proceedings - 1st Congress in Geomatics Engineering - CIGeo

View full text Add to dashboard Cite

show abstract

“…Fig. 1 shows the epicenter of the mainshocks and the larger aftershocks [22]. The figure also shows the focal mechanism of the main events.…”

Section: Ground-motion Recordsmentioning

confidence: 99%

“…The first and second mainshocks have a mostly strike-slip and thrust mechanisms, respectively. Based on precise relocation of the seismic cluster, and neotectonic studies, Ghods et al [22] consider that the events lie on two different faults (Fig. 1).…”

Section: Ground-motion Recordsmentioning

confidence: 99%

Nonlinear response analysis of SDOF systems subjected to doublet earthquake ground motions: A case study on 2012 Varzaghan–Ahar events

Yaghmaei‐Sabegh

Ruiz‐García

2016

Engineering Structures

View full text Add to dashboard Cite

The Post‐Eocene Evolution of the Doruneh Fault Region (Central Iran): The Intraplate Response to the Reorganization of the Arabia‐Eurasia Collision Zone

et al. 2017

View full text Add to dashboard Cite

The Cenozoic deformation history of Central Iran has been dominantly accommodated by the activation of major intracontinental strike‐slip fault zones, developed in the hinterland domain of the Arabia‐Eurasia convergent margin. Few quantitative temporal and kinematic constraints are available from these strike‐slip deformation zones, hampering a full assessment of the style and timing of intraplate deformation in Iran and the understanding of the possible linkage to the tectonic reorganization of the Zagros collisional zone. This study focuses on the region to the north of the active trace of the sinistral Doruneh Fault. By combing structural and low‐temperature apatite fission track (AFT) and (U‐Th)/He (AHe) thermochronology investigations, we provide new kinematic and temporal constraints to the deformation history of Central Iran. Our results document a post‐Eocene polyphase tectonic evolution dominated by dextral strike‐slip tectonics, whose activity is constrained since the early Miocene in response to an early, NW‐SE oriented paleo‐σ1 direction. A major phase of enhanced cooling/exhumation is constrained at the Miocene/Pliocene boundary, caused by a switch of the maximum paleo‐σ1 direction to N‐S. When integrated into the regional scenario, these data are framed into a new tectonic reconstruction for the Miocene‐Quaternary time lapse, where strike‐slip deformation in the intracontinental domain of Central Iran is interpreted as guided by the reorganization of the Zagros collisional zone in the transition from an immature to a mature stage of continental collision.

show abstract

The Varzaghan–Ahar, Iran, Earthquake Doublet (M_w6.4, 6.2): implications for the geodynamics of northwest Iran

Cited by 59 publications

References 46 publications

Stress Transfere and Statistical Analysis of 2012 Ahar-Varzeghan Seismic Sequnce, Northwestern Iran

Stress Transfere and Statistical Analysis of 2012 Ahar-Varzeghan Seismic Sequnce, Northwestern Iran

Nonlinear response analysis of SDOF systems subjected to doublet earthquake ground motions: A case study on 2012 Varzaghan–Ahar events

The Post‐Eocene Evolution of the Doruneh Fault Region (Central Iran): The Intraplate Response to the Reorganization of the Arabia‐Eurasia Collision Zone

Contact Info

Product

Resources

About