Megathrust and accretionary wedge properties and behaviour in the Makran subduction zone

Abstract

We study the Makran subduction zone, along the southern coasts of Iran and Pakistan, to gain insights into the kinematics and dynamics of accretionary prism deformation. By combining techniques from seismology, geodesy and geomorphology, we are able to put constraints on the shape of the subduction interface and the style of strain across the prism. We also address the long-standing tectonic problem of how the right-lateral shear taken up by strike-slip faulting in the Sistan Suture Zone in eastern Iran is accommodated at the zone's southern end. We find that the subduction interface in the western Makran may be locked, accumulating elastic strain, and move in megathrust earthquakes. Such earthquakes, and associated tsunamis, present a significant hazard to populations around the Arabian Sea.

Estimation of Depth to Bottom of Magnetic Sources Using Spectral Methods: Application on Iran's Aeromagnetic Data

“…The most striking feature of the map is the deep DBMS (~40 km thick) over Makran accretionary wedge. The deep DBMS is in agreement with the presence of a thick sedimentary cover of >10 km (Teknik & Ghods, ) overlying over an old (~80–100 Ma, Gaina et al, ) almost flat oceanic lithosphere (e.g., Penney et al, ). The oceanic plate cooling model of Stein and Stein () suggests a depth of ~40 km for Curie isotherm of the oceanic lithosphere of age 80–100 Ma, closely in agreement with the calculated DBMS in the Makran accretionary wedge.…”

“…Journal of Geophysical Research: Solid Earth almost flat oceanic lithosphere (e.g., Penney et al, 2017). The oceanic plate cooling model of Stein and Stein (1992) suggests a depth of~40 km for Curie isotherm of the oceanic lithosphere of age 80-100 Ma, closely in agreement with the calculated DBMS in the Makran accretionary wedge.…”

Extension at the coast of the Makran subduction zone (Iran)

“…(b) Map showing GPS velocities with a fixed Arabian plate reference. Data based on the compilation by Penney et al () from the existing literature (see Section 3 for references). The square delineates the study area.…”

“…However, some authors agree, based on geophysical properties and the observation of palaeoseismic evidence, that the western Makran has the potential to produce large subduction earthquakes (e.g. Penney et al, ; Rajendran et al, ; Schneider, Hoffmann, Falkenroth, & Grade, ; Smith, McNeill, Wang, He, & Henstock, ) , and the threat related to potential Makran earthquakes and associated tsunamis is considered serious (UNESCO‐IOC, ).…”

“…Geodetic data from GPS stations on the Eurasian plate show SSW convergence relative to a fixed Arabian plate, at a rate of ~2 cm/a (Figure b,c) (Bayer et al, ; Frohling & Szeliga, ; Khan, ; Masson et al, ; Penney et al, ; Peyret et al, ; Vernant et al, ; Walpersdorf et al, ). This rate progressively decreases from N to S (Figure b,c), indicating that the coastal portion of the Makran is currently accumulating N–S compressive strain.…”