Crustal Structure of the Collision-Subduction Zone in South of Iran Using Virtual Seismometers

Abstract

Improving the resolution of seismic tomography by adding virtual seismometers is an ambitious aim in regions with poor instrumental coverage. In this study, inter-event empirical Green’s functions (EGFs) were retrieved using cross-correlation of the vertical component of 630 earthquakes with M ≥ 4 which occurred around the collision-subduction transition zone in south Iran. To extract reliable inter-event EGFs and obtain stable tomographic results, we used about 1300 event pairs with good signal-to-noise ratio, each pair well aligned to a seismic station. Our results show that the retrieved inter-event EGFs agree well with those obtained from earthquakes in similar paths. The inverted velocity model presents two main layers including upper crust (up to ~16 km) and middle crust (deeper than ~18 km) in both sides of the Minab-Zendan-Palami transition zone. The upper crust contains two main layers: sedimentary and basement layers with thicknesses ~6 and ~10 km, respectively. Moreover, the main faults cause lateral variations in these main layers. The difference between the average velocities of the middle crust, between the collision and subduction zones, is about 0.5 km/s, delimited by faults. Also, an area with a 30 km width along these faults can be defined as the collision-subduction transition zone.

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

“…The Iranian plateau is part of the Alps and Himalayas' Orogenic Belt, which presents high seismic activity and a unique deformation scheme. The movement's pressure converging between the Arabian plate and the Turan shield built mountain ranges in Iran [6]. The significant tectonic activity, along with the Zagros collision and the Makran subduction, results from this convergence [44, 45,46].…”

“…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].…”

How much the Iranian government spent on disasters in the last 100 years? A critical policy analysis

“…West of Iran (along the Zagros collision) is earthquake prone because of the collision of Arabian and Eurasian plates. In addition, the south of Iran is along the Makran subduction is also seismically active [ 60 ]. Examples of tragic earthquakes in Iran can be seen in Qazvin earthquake in 1962, Khorasan earthquake (1948), Khakhk earthquake in 1968, Dashti Biaz earthquake in Khorasan province (in 1931,1941,1947, and 1962), Tabas earthquake (1978), Manjil–Rudbar earthquake in 1990, Bam earthquake in 2003, Kermanshah earthquake in 2017 [ 61 – 64 ].…”

On the Formation of Global Inter‐Source Correlations and Applications to Constrain the Interiors of the Earth and Other Terrestrial Planets

“…This allows for forming deep virtual seismometers to detect seismic signals sensitive to deep‐earth structures with minimal signal disturbance due to shallow‐depth structure heterogeneities (Shen & Zhan, 2020; Shen et al., 2021). Also, the inter‐source correlations are used for imaging crustal structures (Shirzad et al., 2019), shear‐wave velocities in areas around different source clusters (Eulenfeld, 2020), and monitoring of micro‐earthquakes (Morency & Matzel, 2017).…”