The present‐day stress field in the Zagros Fold-Thrust Belt of Iran, from inversion of focal mechanisms

Khanban, Mohammad Ali; Pakzad, Mehrdad; Mirzaei, Noorbakhsh; Moradi, Ali; Mehramuz, Mahmoud

doi:10.1016/j.jog.2020.101812

Cited by 6 publications

(2 citation statements)

References 31 publications

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“…The epicenter of the Sarpol Zahab earthquake located at the boundary of two subzones with relatively uneven stress distribution, and MRF is the most active seismotectonic structure in the Zagros region (Khanban et al, 2021). The dynamic alteration of local stress in lithosphere might have been much more activated prior to the Sarpol Zahab earthquake, which led to the preseismic deformation (Vaka et al, 2019) and micro cracks of deep-to-shallow rock mass.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Discriminating the Multi-Frequency Microwave Brightness Temperature Anomalies Relating to 2017 Mw 7.3 Sarpol Zahab (Iran-Iraq Border) Earthquake

Ding

et al. 2021

Front. Earth Sci.

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A Mw 7.3 earthquake occurred near the Iran-Iraq border on November 12, 2017, as the result of oblique-thrust squeezing of the Eurasian plate and the Arabian plate. By employing the spatio-temporally weighted two-step method (STW-TSM) and microwave brightness temperature (MBT) data from AMSR-2 instrument on board Aqua satellite, this paper investigates carefully the spatiotemporal features of multi-frequency MBT anomalies relating to the earthquake. Soil moisture (SM), satellite cloud image, regional geological map and surface landcover data are utilized to discriminate the potential MBT anomalies revealed from STW-TSM. The low-frequency MBT residual images shows that positive anomalies mainly occurred in the mountainous Urmia lake and the plain region, which were 300 km north and 200 km southwest about to the epicenter, respectively. The north MBT anomaly firstly appeared 51 days before the mainshock and its magnitude increased over time with a maximum of about +40K. Then the anomaly disappeared 3 days before, reappeared 1d after and diminished completely 10 days after the mainshock. Meanwhile, the southwest MBT anomaly firstly occurred 18 days before and peaked 3 days before the mainshock with a maximum of about +20K, and then diminished gradually with aftershocks. It is speculated that the positive MBT anomaly in the Urmia lake was caused by microwave dielectric property change of water body due to gas bubbles leaking from the bottom of the lake disturbed by local crust stress alteration, while the southwest MBT positive anomaly was caused by microwave dielectric constant change of shallow surface due to accumulation of seismically-activated positive charges originated at deep crust. Besides, some accidental abnormal residual stripes existed in line with satellite orbit, which turned out to be periodic data errors of the satellite sensor. High-frequency MBT residual images exhibit some significant negative anomalies, including a narrow stripe pointing to the forthcoming epicenter, which were confirmed to be caused by synchronous altostratus clouds. This study is of guidance meaning for distinguishing non-seismic disturbances and identifying seismic MBT anomaly before, during and after some large earthquakes.

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Section: Conclusion and Discussionmentioning

confidence: 99%

Discriminating the Multi-Frequency Microwave Brightness Temperature Anomalies Relating to 2017 Mw 7.3 Sarpol Zahab (Iran-Iraq Border) Earthquake

Ding

et al. 2021

Front. Earth Sci.

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“…The high level of seismic activity is a consequence of the convergence of Arabian and Eurasian plates. The continental-continental collision in the west of Iran, along with the Zagros collision and subduction in the south of Iran along the Makran subduction, results from the convergence [5,6]. The convergence rate measured by GPS varies from 10 mm/yr in Zagros thrust to 28 mm/yr in the Makran subduction zone [7].…”

Section: Introductionmentioning

confidence: 99%

The role of the cell shapes on the characteristics of a complex earthquake network

2022

ijp

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We studied the behavior of the earthquake network using the HEALPix spherical pixelization and square cells methods. In the first method, the geographical region is divided into isolatitude rhombic-spherical cells of the same areas using the HEALPix method. In the second method, we divided the geographical region into isolatitude equal areas of the square cells. To construct a network, if an earthquake happens in a cell, that cell will become a node, and two nodes will be connected with an edge for two successive events. The earthquake network is built from Iran's seismic data from 1900 June 12 to 2015 December 12. We determined the Hurst exponent (H = 0.6) due to the rescaled range (R/S) analysis. This value reveals a long temporal correlation in earthquake time-series; therefore, the earthquake system is suggested to be self-organized. We showed that among the five major seismotectonic provinces of Iran (Alborz-Azarbayejan, Kope Dagh, Central-East Iran, Zagros, and Makran), the earthquake network hubs are located in the Zagros region, which is a seismically very active region. According to this result, the Zagros earthquakes affect the surrounding earthquakes. The probability distribution function's power-law behavior with a network built in the pixelization rhombic-spherical cells shows scale free behavior's properties than a network constructed based on the square cells. The mean clustering coefficient's power-law nature with networks built using two methods shows that the earthquake network is scale-free and non-random. We concluded that the rhombic-spherical cell pixelization is a more reliable method for building the large geographical region's earthquake network.

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Complex Geosites as a Unique Resource and Challenge for Management: Evidence from an Exposed Salt Diapir

2022

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The present‐day stress field in the Zagros Fold-Thrust Belt of Iran, from inversion of focal mechanisms

Cited by 6 publications

References 31 publications

Discriminating the Multi-Frequency Microwave Brightness Temperature Anomalies Relating to 2017 Mw 7.3 Sarpol Zahab (Iran-Iraq Border) Earthquake

Discriminating the Multi-Frequency Microwave Brightness Temperature Anomalies Relating to 2017 Mw 7.3 Sarpol Zahab (Iran-Iraq Border) Earthquake

The role of the cell shapes on the characteristics of a complex earthquake network

Complex Geosites as a Unique Resource and Challenge for Management: Evidence from an Exposed Salt Diapir

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