State of stress induced by plate convergence and stress partitioning in northeastern Iran, as indicated by focal mechanisms of earthquakes

Zamani, G Behzad; Angelier, Jacques; Ahmad, Zaini

doi:10.1016/j.jog.2007.07.003

Cited by 36 publications

(22 citation statements)

References 36 publications

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“…No strong stress signal is observed in the Lut and central Iran blocks in Figure 5 which confirms the statement of (Jackson and McKenzie 1984) about that fact that these areas are virtually aseismic and behaving as relatively rigid body. The studies of Zamani et al (2008) confirm the agreement of the geodetic information and seismotectonic stress results in the Alborz area, placed in the northern part of Iran. Masson et al (2005) suggested the highly strained zones experience mainly aseismic deformation in southern Iran and seismic deformation in the northern, which resulted a major contrast, more than 50-100% between their seismic deformations.…”

Section: Tablesupporting

confidence: 81%

“…Masson et al (2005) suggested the highly strained zones experience mainly aseismic deformation in southern Iran and seismic deformation in the northern, which resulted a major contrast, more than 50-100% between their seismic deformations. This means that the active deformation in northern part may have been underestimated with respect to the southern part (Zamani et al 2008). However, the recovered sub-lithospheric stress field in Figure 5 shows that the stresses in the northern and southern part of Iran are more or less of the same order.…”

Section: Tablementioning

confidence: 99%

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Determination of sub-lithospheric stress due to mantle convection using GOCE gradiometric data over Iran

Eshagh

Romeshkani

2015

Journal of Applied Geophysics

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Section: Tablesupporting

confidence: 81%

Section: Tablementioning

confidence: 99%

Determination of sub-lithospheric stress due to mantle convection using GOCE gradiometric data over Iran

Eshagh

Romeshkani

2015

Journal of Applied Geophysics

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“…One of these units is Kopet Dagh which is located in the northeast of Iran (Ramazani Oomali et al 2008), stretching from the Caspian Sea along the Turkmenistan border to Afganistan (Zamani et al 2008). The study area is located in the Kopet Dagh Zone.…”

Section: Geologymentioning

confidence: 99%

Water leakage paths in the Doosti Dam, Turkmenistan and Iran

2011

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The Doosti Dam, with a reservoir capacity of 1,250 million cubic meters, was constructed on the Harirood River at the border of Turkmenistan and Iran. The reservoir is in direct contact with permeable formations on the right abutment of the dam including the Neyzar Sandstone, the Kalat Limestone and the Pesteleigh alternative layers of marlstone and sandstone. After the reservoir impoundment, several new springs and seepages emerged from these formations and the alluvium. The amount of leakage increased with the rise in reservoir water level. Fifteen kilograms of sodium fluorescein were injected into a 113-m deep borehole intersecting three permeable sandstone layers of the Pesteleigh formation. Dye was detected downstream of the grout curtain in boreholes and springs that were in direct contact with parts of the Pesteleigh formation having the same sandstone layers as the injection borehole. The dye velocity was in the range of diffuse flow, confirming the good performance of the grout curtain in the Pesteleigh formation. No dye was detected in the other formations because the injection borehole was not in direct contact with these formations. The hydraulic relation of the other formations with the reservoir was determined by considering direct contact of the formations with the reservoir, emergence of new springs and seepages after reservoir impoundment, correlation of time variations of the springs discharge and the borehole's water level with the reservoir water level, and in some cases the hydrochemistry of the water. The results show that the Kalat and Neyzar formations are hydraulically connected to the reservoir, but the small amounts of leakage from these formations at a hydraulic gradient of 24% indicates good performance of the built grout curtain. The total reservoir leakage at maximum reservoir water level was 100 l/s which is insignificant compared with the 15 m 3 /s average annual release of the reservoir.

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“…1) mountain ranges [19] in northern Iran, east-central Iran is generally considered to be relatively quiet seismically [5]. During recent years, however, there has been an increase in large and moderate earthquake activity in central Iran.…”

Section: Seismotectonic Activitymentioning

confidence: 99%

State of stress in the northern Tabas block, east-central Iran, as inferred from focal mechanisms of the 1978 Tabas earthquake sequence

Zamani

2011

Open Geosciences

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Abstract:In this paper, the state of stress in the northern Tabas block in east-central Iran is analyzed based on the systematic inversion of aftershock focal mechanisms from the 1978.09.16 Tabas earthquake, to characterise the stress regime that controls most earthquakes in this area. Here, stress inversions of double-couple focal mechanisms of earthquakes recorded during the 30 days following the main shock have been carried out. The calculated average stress regime indicates dominant major 226 • to 237 • trending compression for the Tabas region. The dominating regime in east-central Iran is thrusting with a minimum stress axis, σ 3 , close to vertical. The reconstruction of the main seismotectonic stress in east-central Iran with a NE-SW compression is consistent with independent information of the active plate convergence related to Arabia-Eurasia convergence. Most earthquakes in the mentioned area occur near or around concealed Quaternary thrust faults with their activity being controlled by the NE-SW compression. Where Φ, the ratio of principal stress differences, is 0.5, a small difference between σ 2 σ 3 and σ 1 and small amounts of deviatoric stress is indicated. Therefore, for small deviatoric horizontal σ 1 it is not possible to increase and reactivate small sections of basement thrust faults and create secondary basement aftershocks. Reconstructed stress regimes in this study for sedimentary cover (237) and basement (226) of Tabas are similar. Therefore, it seems that the basement and cover were coupled together, possibly along the 2-4 km of upper Precambrian low-grade metamorphic rocks. Then these segments of the fold-and-thrust belt were involved in similar seismic activity under a similar stress regime. IntroductionIran is located within the convergence domain between the Arabian and Eurasian plates. The central parts of * E-mail: b.zamani@tabrizu.ac.ir, Tel: +98 411 3392700, fax: +98 411 4448914Iran move northwards with respect to western Afghanistan at˜15 mm yr −1 [1]. This northward motion introduces 15 mm yr −1 of north-south right-lateral shear across eastern Iran which is accommodated on right-lateral strike-slip fault systems on both the western (GowakNayband fault system) and eastern (Neh and Zendan fault systems) margins of the aseismic Dashte-e Lut desert [2,3]. The study area is situated in the eastern part of central Iran, and northern part of the Tabas block ( Fig. 1). Tabas is a town with approximately 30,000 inhabitants, 950 kilometers southeast of Tehran. The city was hit by a major destructive earthquake on September 16 th 1978, during which about 22,000 lost their lives. The recorded earthquake magnitude was between 7.5 and 7.9 on the Richter scale. Despite the major tectonic hazard in the Tabas region, relatively few studies have attempted to analyze the local-scale seismotectonic stress regime. Consequently, this research aims to characterise the stress regime which controls most of the earthquakes occurring in this area through an inversion of the earthquake focal mechanisms...

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State of stress induced by plate convergence and stress partitioning in northeastern Iran, as indicated by focal mechanisms of earthquakes

Cited by 36 publications

References 36 publications

Determination of sub-lithospheric stress due to mantle convection using GOCE gradiometric data over Iran

Determination of sub-lithospheric stress due to mantle convection using GOCE gradiometric data over Iran

Water leakage paths in the Doosti Dam, Turkmenistan and Iran

State of stress in the northern Tabas block, east-central Iran, as inferred from focal mechanisms of the 1978 Tabas earthquake sequence

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