The 2017 July 20 Mw 6.6 Bodrum–Kos earthquake illuminates active faulting in the Gulf of Gökova, SW Turkey

Karasözen, Ezgi; Nissen, Edwin; Büyükakpınar, Pınar; Cambaz, Musavver Didem; Kahraman, M.; Ertan, Esra KalkanÂ; Abgarmi, Bizhan; Bergman, Eric; Ghods, Abdolreza; Özacar, A. Arda

doi:10.1093/gji/ggy114

Cited by 41 publications

(38 citation statements)

References 62 publications

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“…Use of an alternative velocity model (Acarel et al., 2019) increased waveform model centroid depths by on average ∼2 km, reducing but not eliminating this discrepancy. These results mimic relations observed in comparably instrumented regions elsewhere (Gaudreau et al., 2019; Karasözen et al., 2016, 2018) and likely reflect the depth resolution limitations of both methods, together with the propensity for earthquakes to nucleate deeper within the seismogenic zone and rupture upward.…”

Section: Resultssupporting

confidence: 79%

The 2020 M_w 6.8 Elazığ (Turkey) Earthquake Reveals Rupture Behavior of the East Anatolian Fault

Pousse‐Beltran

Nissen

Bergman

et al. 2020

Geophysical Research Letters

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The 2020 Mw 6.8 Elazığ earthquake was the largest along the East Anatolian Fault (EAF) in over a century, providing valuable insights into its rupture behavior. We use satellite geodesy and seismology to detail the mainshock rupture, postseismic deformation, and aftershocks. The mainshock propagated mostly westward at ∼2 km/s from a nucleation point on an abrupt ∼10° fault bend. Only one end of the rupture corresponds to an established EAF segment boundary, and the earthquake may have propagated into the slip zone of the 1874 M ∼ 7.1 Gölcuk Gölu earthquake. It exhibits a pronounced (∼80%) shallow slip deficit, only a small proportion of which is recovered by early aseismic afterslip. The slow rupture velocity, shallow slip deficit, and minimal afterslip are characteristic of earthquakes hosted by faults of low‐to‐intermediate structural maturity, indicating that faults continue to evolve in important ways even as they accrue cumulative offsets of tens of kilometers.

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Section: Resultssupporting

confidence: 79%

The 2020 M_w 6.8 Elazığ (Turkey) Earthquake Reveals Rupture Behavior of the East Anatolian Fault

Pousse‐Beltran

Nissen

Bergman

et al. 2020

Geophysical Research Letters

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“…First, it solves for the cluster vectors that connect each event hypocenter to the hypocentroid—defined as the geometric mean of all hypocenters—using all available data at any epicentral distance. Second, it calculates the absolute location of the hypocentroid and updates the absolute hypocenter coordinate of every event in the cluster, using either phase picks at close‐in stations that record direct Pg and Sg arrivals (termed direct calibration ), or ground truth locations of one or more events in the cluster determined by independent means ( indirect calibration ; e.g., Ghods et al, , ; Karasözen et al, , ; Walker et al, ).…”

Section: Methodsmentioning

confidence: 99%

The 12 November 2017 M_w 7.3 Ezgeleh‐Sarpolzahab (Iran) Earthquake and Active Tectonics of the Lurestan Arc

et al. 2019

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The 12 November 2017 Mw 7.3 Ezgeleh‐Sarpolzahab earthquake is the largest instrumentally recorded earthquake in the Zagros Simply Folded Belt by a factor of ∼10 in seismic moment. Exploiting local, regional, and teleseismic data and synthetic aperture radar interferometry imagery, we characterize the rupture, its aftershock sequence, background seismicity, and regional tectonics. The mainshock ruptured slowly (∼2 km/s), unilaterally southward, for ∼40 km along an oblique (dextral‐thrust) fault that dips ∼14°E beneath the northwestern Lurestan arc. Slip is confined to basement depths of ∼12–18 km, resolvably beneath the sedimentary cover which is ∼8 km thick in this area. The gentle dip angle and basement location allow for a broad slip area, explaining the large magnitude relative to earthquakes in the main Fars arc of the Zagros, where shallower, steeper faults are limited in rupture extent by weak sedimentary layers. Early aftershocks concentrate around the southern and western edges of the mainshock slip area and therefore cluster in the direction of rupture propagation, implying a contribution from dynamic triggering. A cluster of events ∼100 km to the south near Mandali (Iraq) reactivated the ∼50° dipping Zagros Foredeep Fault. The basement fault responsible for the Ezgeleh‐Sarpolzahab earthquake probably accounts for the ∼1 km elevation contrast between the Lurestan arc and the Kirkuk embayment but is distinct from sections of the Mountain Front Fault that define frontal escarpments elsewhere in the Zagros. It may be related to a seismic interface underlying the central and southern Lurestan arc, and a key concern is whether or not the more extensive regional structure is also seismogenic.

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“…We reanalyze the ∼70‐year back‐catalog of instrumentally recorded seismicity in the Zagros using the mloc multiple‐earthquake relocation technique that has been specialized for studies of absolute, calibrated locations (Bergman & Solomon, ; Karasözen et al, ; Walker et al, ). Mloc is based on the hypocentroidal decomposition (HD) algorithm of Jordan and Sverdrup () that seeks to minimize the location bias arising from unknown Earth velocity structure.…”

Section: Calibrated Earthquake Locationsmentioning

confidence: 99%

Seismotectonics of the Zagros (Iran) From Orogen‐Wide, Calibrated Earthquake Relocations

et al. 2019

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We use calibrated earthquake relocations to reassess the distribution and kinematics of faulting in the Zagros range, southwestern Iran. This is among the most seismically active fold‐and‐thrust belts globally, but knowledge of its active faulting is hampered by large errors in reported epicenters and controversy over earthquake depths. Mapped coseismic surface faulting is extremely rare, with most seismicity occurring on blind reverse faults buried beneath or within a thick, folded sedimentary cover. Therefore, the distribution of earthquakes provides vital information about the location of active faulting at depth. Using an advanced multievent relocation technique, we relocate ∼2,500 earthquakes across the Zagros mountains spanning the ∼70‐year instrumental record. Relocated events have epicentral uncertainties of 2–5 km; for ∼1,100 of them we also constrain origin time and focal depth, often to better than 5 km. Much of the apparently diffuse catalog seismicity now collapses into discrete trends highlighting major active faults. This reveals several zones of unmapped faulting, including possible conjugate left‐lateral faults in the central Zagros. It also confirms the activity of faults mapped previously on the basis of geomorphology, including oblique (dextral‐normal) faulting in the NW Zagros. We observe a primary difference between the Lurestan arc, where seismicity is focused close to the topographic range front, and the Fars arc, where out‐of‐sequence thrusting is evident over a width of ∼100–200 km. We establish a focal depth range of 4–25 km, confirming earlier suggestions that earthquakes are restricted to the upper crust but nucleate both within and beneath the sedimentary cover.

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The 2017 July 20 Mw 6.6 Bodrum–Kos earthquake illuminates active faulting in the Gulf of Gökova, SW Turkey

Cited by 41 publications

References 62 publications

The 2020 M_w 6.8 Elazığ (Turkey) Earthquake Reveals Rupture Behavior of the East Anatolian Fault

The 2020 M_w 6.8 Elazığ (Turkey) Earthquake Reveals Rupture Behavior of the East Anatolian Fault

The 12 November 2017 M_w 7.3 Ezgeleh‐Sarpolzahab (Iran) Earthquake and Active Tectonics of the Lurestan Arc

Seismotectonics of the Zagros (Iran) From Orogen‐Wide, Calibrated Earthquake Relocations

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The 2017 July 20 Mw 6.6 Bodrum–Kos earthquake illuminates active faulting in the Gulf of Gökova, SW Turkey

Cited by 41 publications

References 62 publications

The 2020 Mw 6.8 Elazığ (Turkey) Earthquake Reveals Rupture Behavior of the East Anatolian Fault

The 2020 Mw 6.8 Elazığ (Turkey) Earthquake Reveals Rupture Behavior of the East Anatolian Fault

The 12 November 2017 Mw 7.3 Ezgeleh‐Sarpolzahab (Iran) Earthquake and Active Tectonics of the Lurestan Arc

Seismotectonics of the Zagros (Iran) From Orogen‐Wide, Calibrated Earthquake Relocations

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Product

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The 2020 M_w 6.8 Elazığ (Turkey) Earthquake Reveals Rupture Behavior of the East Anatolian Fault

The 2020 M_w 6.8 Elazığ (Turkey) Earthquake Reveals Rupture Behavior of the East Anatolian Fault

The 12 November 2017 M_w 7.3 Ezgeleh‐Sarpolzahab (Iran) Earthquake and Active Tectonics of the Lurestan Arc