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| Zagros Main Recent Fault | |
|---|---|
| Name | Zagros Main Recent Fault |
| Other names | Main Recent Fault |
| Country | Iran |
| Region | Zagros Mountains |
| Length km | 1200 |
| Type | Thrust and strike-slip |
| Plate | Arabian Plate, Eurasian Plate |
| Status | Active |
Zagros Main Recent Fault is a major active fault system that accommodates convergence between the Arabian Plate and the Eurasian Plate across the Zagros Mountains of western and southwestern Iran. The structure forms part of a complex network of thrusts, folds and strike-slip faults that link regional features such as the Sanandaj-Sirjan Zone, the Urmia-Dokhtar Magmatic Arc and the Persian Gulf margin. It has been central to regional tectonics, seismic hazard, and oil-bearing structural evolution in the Fars Province, Khuzestan Province, and adjacent provinces.
The fault system trends NW–SE along the length of the mountain belt, extending from near the triple junction with the Anatolian Fault and the Bitlis-Zagros junction in the northwest toward the Gulf of Oman and the Persian Gulf in the southeast. It links with major structural belts including the High Zagros Fault, the Kazerun Fault System, and the Zagros Hinterland thrusts. Key population centers and infrastructure—such as Shiraz, Ahvaz, Kermanshah, and major oilfields near Masjed Soleyman—lie within influence of the fault’s deformation zone.
The fault lies within a convergent collision zone where northward motion of the Arabian Plate beneath or against the Eurasian Plate produces crustal shortening, uplift, and thick-skinned deformation. The regional stratigraphy includes Paleozoic to Cenozoic sedimentary sequences with prominent Jurassic to Miocene carbonate platforms that host hydrocarbons in the Zagros Fold Belt. Basement complexes such as the Sanandaj metamorphic zone and the Urmia-Dokhtar magmatic arc influence fault geometry. The tectonic framework also interacts with the Makran Subduction Zone to the southeast and the collision-related structures of the Central Iranian Plateau.
The fault system is characterized by segmentation into discrete strands, step-overs, and splays that produce variable displacement and folding across strike. Segmentation names commonly used in the literature include strands adjacent to the High Zagros and subsidiary splays toward the foreland basins such as the Dezful Embayment and Gachsaran Formation exposures. Kinematic styles vary from oblique-thrust to right-lateral strike-slip along different segments, controlled by pre-existing basement heterogeneities and the orientation of basement faults like the Kuh-e-Sabz and Bavanat trends. Geophysical imaging including seismic reflection and gravity surveys has revealed listric geometries, décollement horizons, and blind-thrust segments beneath major anticlines.
Seismic catalogs show frequent moderate to large earthquakes associated with the system and adjacent faults, with notable events recorded near Tabriz (regional context), Rudbar, and historic ruptures affecting Kermanshah and Luristan provinces. Significant historic earthquakes, documented in chronicles preserved in archives related to Safavid and Qajar eras, highlight vulnerability of urban centers such as Shushtar and Behbahan. Instrumental records from the International Seismological Centre and regional seismic networks document events with focal mechanisms consistent with reverse and oblique-reverse slip along NW–SE trending structures, often producing surface folding rather than continuous surface rupture.
Trenching studies, uplift histories of marine terraces along the Persian Gulf margin, and stratigraphic correlations in foreland basins have been used to estimate long-term slip rates and recurrence intervals. Estimated Holocene slip rates vary by segment but commonly fall in the range of a few millimeters to ~10 mm/yr, consistent with plate convergence rates inferred from GPS results across Iran and the broader Arabia–Eurasia convergence. Paleoseismic evidence for repeated large events is recorded in fault scarps, displaced fluvial terraces, and colluvial wedges near sites studied by teams from institutions such as the Institute of Geophysics, University of Tehran and international collaborations with universities in France, Germany, and the United Kingdom.
Assessment integrates geology, seismology, geodesy, and remote sensing from platforms like ERS, RADARSAT, and modern Sentinel satellites to map active deformation, landslide susceptibility, and seismic source models for urban planning in provinces including Fars and Khuzestan. Hazard models developed for pipeline corridors, oil and gas facilities in the Assaluyeh and Ahvaz regions, and lifeline infrastructure use fault geometry, slip-rate constraints, and probabilistic seismic hazard frameworks practiced by organizations such as the National Cartographic Center of Iran and international agencies. Early warning, seismic monitoring, and building-code enforcement remain priorities for reducing societal impact.
Key debates concern the partitioning of convergence between discrete thrusting and distributed shortening, the role of basement-involved versus detachment-style deformation, and precise slip-rate quantification for hazard forecasting. Competing interpretations by research groups from Tarbiat Modares University, Sharif University of Technology, and international collaborators have argued for different segmentation models and coupling of the fault with deeper crustal structures imaged by magnetotelluric and seismic tomography studies. Ongoing work aims to reconcile paleoseismic records with GPS-derived strain accumulation and to integrate petroleum exploration datasets with seismotectonic models.
Category:Seismic faults of Iran Category:Zagros Mountains Category:Geology