Active deformation in Zagros-Makran transition zone inferred from GPS measurements

Abstract

International audienceThe Bandar Abbas-Strait of Hormuz zone is considered as a transition between the Zagros collision and the Makran oceanic subduction. We used GPS network measurements collected in 2000 and 2002 to better understand the distribution of the deformation between the collision zone and the Makran subduction. Analysing the GPS velocities, we show that transfer of the deformation is mainly accommodated along the NNW-SSE-trending reverse right-lateral Zendan-Minab-Palami (ZMP) fault system. The rate is estimated to 10 +/- 3 mm yr-1 near the faults. Assuming that the ZMP fault system transfers the motion between the Makran-Lut Block and the Arabian plate, we estimate to 15 mm yr-1 and 6 mm yr-1, respectively, the dextral strike-slip and shortening components of the long-term transpressive displacement. Our geodetic measurements suggest also a 10-15 km locking depth for the ZMP fault system. The radial velocity pattern and the orientation of compressive strain axes around the straight of Hormuz is probably the consequence of the subducting Musandam promontory. The N-S Jiroft-Sabzevaran (JS) fault system prolongates southwards the dextral shear motion of the Nayband-Gowk (NG) fault system at an apparent rate of 3.1 +/- 2.5 mm yr-1. The change from strong to weak coupling for underthrusting the Arabian plate beneath the Zagros (strong) and the Makran (weak) may explain the dextral motion along the ZMP, JS/NG and Neh-Zahedan fault systems which transfer the convergence from a broad zone in the western Iran (Zagros, Tabriz fault system, Alborz, Caucasus and Caspian sea surroundings) to Makran subduction

The transition between Makran subduction and the Zagros collision: recent advances in its structure and active deformation

“…Interestingly, the Hormoz strait area in Iran (26.5°N; 56.5°E, Figure 1) displays such a setting, but in a juvenile stage. At this point Arabia converges northward towards Eurasia at a velocity of 23-25 mm yr -1 according to GPS measurements (Bayer et al, 2003;McClusky et al, 2003;Vernant et al, 2004;Bayer et al, 2006;Masson et al, 2007). The Arabian plate is oceanic to the east in the Oman Gulf whereas it is continental to the west in the Arabian platform (Figure 1).…”

Tsunami in Makran Region and Its Effect on the Persian Gulf

“…Despite the above fact, the lack of major earthquakes in the western segment means either the segment has been locked for hundreds of years or this segment is creeping aseismically. However, the regional GPS measurements indicate a convergence rate of about 2 cm/year (Bayer et al, 2006). In addition, the existence of Holocene (10000 years) marine terraces (Page et al, 1979) indicates that this segment is active, although the recurrence period of megathrust earthquakes events may be much longer (i.e.…”

Seismic Source Modeling in the Shores of Western Makran

“…Reference [9] attributes the absence of earthquake events in the western Makran, to the presence of huge amounts of non-stiffened saturated sediments which have low internal friction angle and therefore they do not have seismic activity. However, presence of marine terraces and 9 mud volcanos is a proof for dynamicity of this region, an evidence of which is the Pasty Urama earthquake of 1945 with the magnitude of 8.3 [1].…”