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Rupture History and and Elastic Interaction of the 2022 Multiple Earthquakes in the Zagros Mountains, Iran

Description: 

Earthquake multiplets are defined as two or more consecutive earthquakes that occur within a short period of time and have a comparable magnitude and therefore differ from the typical mainshock-aftershock distribution. With in two hours on the 1^st of July 2022, three earthquakes of M_w 5.8–6.0 hit the SE Fars Arc (FA), Iran. The FA is the 700-km-long, easternmost segment in the foreland of the Zagros continental collision zone, which is characterized by ~10 km thick sediments including extended evaporitic layers causing folding, thin and thick sheet sliding, syn- and anticline formations and extensive strain decoupling. This exceptional setting in the FA and the Zagros mountains also hosts frequent earthquake doublets.

Here we investigate the co-seismic deformation and elastic interaction between both the large mainshocks and 120 aftershocks. We use seismic and satellite deformation data with well-proven and newly developed earthquake parameter estimation tools. Our results indicate the activation of thrust faults within the lower sedimentary cover (<10 km) along with high aftershock activity at significantly larger depths (10 - 15 km). The two largest earthquakes of the triplet (both M_w ∼ 6.0) ruptured the lower sediments at depths of 4 – 9 km, likely occurring on a south-dipping splay fault to the mapped Zagros Foredeep Fault beneath an anticline. The third, smaller, M_w 5.8 event occurred one minute before the second large event, and indicates either an early activation of deeper strata or a possible foreshock co-located on the mainshock faults. The comprehensive analysis of main- and aftershocks using available seismic and ground deformation data unravels the interaction of the July–December 2022 sequence with the sedimentary layers both above and below the evaporitic decoupling zone.

Session: Illuminating Complex, Multiplet Earthquake Sequences at Kahramanmaras (Turkiye), Herat (Afghanistan), and Beyond [Poster Session]

Type: Poster

Date: 5/2/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: Pinar

Student Presenter: No

Invited Presentation: 

Authors