The 2020 Mw 6.8 Elazig earthquake was the largest along the Eastern 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 westwards 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 Golcuk Golu 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 low 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 off sets of tens of kilometers

We investigate the origin of a long-lived earthquake cluster in the Fars arc of the Zagros Simply Folded Belt that is co-located with the major Shanul natural gas field near the small settlement of Khalili. The cluster emerged in January 2019 and initially comprised small events of w 5.4 and 5.7 earthquakes, which were followed by > 100 aftershocks. We assess the spatio-temporal evolution of the earthquake sequence using multiple event hypocenter relocations, waveform inversions, and Sentinel-1 Interferometric Synthetic Aperture Radar (InSAR) measurements and models. We find that the early part of the sequence is spatially distinct from the June 9, 2020 earthquakes and their aftershocks. Moment tensors, centroid depths, and source parameter uncertainties of fifteen of the largest (Mn ≥ 4.0) events show that the sequence is dominated by reverse faulting at shallow depths (mostly ≤ 4 km) within the sedimentary cover. InSAR modelling shows that the Mw 5.7 mainshock occurred at depths of 2–8 km, with a rupture length and maximum slip of ~20 km and ~0.5 m, respectively. Our results strongly suggest that the 2019-2020 Khalili earthquake sequence was influenced by the operation of the Shanul field, making these the first known examples of gas extraction anthropogenic earthquakes in Zagros. Understanding the genesis of such events to distinguish man-made seismicity from natural earthquakes is helpful for hazard and risk assessment, notably in Iran which is both seismically-active and rich in oil and gas reserves.

The 15 May 2020 Mw 6.5 Monte Cristo Range earthquake (MCRE) in Nevada, USA is the largest instrumental event in the Mina deflection, an E-trending stepover zone of highly diffuse faulting within the Walker Lane. The MCRE mostly ruptured previously unmapped faults, motivating us to characterize the behaviour of an earthquake on a structurally-immature fault. We use Interferometric Synthetic Aperture Radar (InSAR) data and regional GNSS offsets to model the causative faulting. Our three fault model indicates almost pure left-lateral motion in the east and normal-sinistral slip in the west. Maximum slip of 1.1 m occurs at 8-10 km depth but less than 0.2 m of slip reaches the surface, yielding a pronounced shallow slip deficit (SSD) of 86%. Our calibrated relocated hypocenters and focal mechanisms indicate that the mainshock initiated at 9 km depth and aftershock focal depths range from 1 to 11 km, helping constrain the local seismogenic thickness. We further present new field observations of fracturing and pebble-clearing that shed light on the western MCRE kinematics, revealing a paired fault system below the spatial resolution of the InSAR model. The segmented fault geometry, off-fault aftershocks with variable mechanisms, distributed surface fractures, limited long-term geomorphic features, and an estimated cumulative offset of 600-700 m, are all characteristic of a structurally-immature fault system. However, the large SSD is not unusual for an earthquake of this magnitude, and a larger compilation of InSAR models (twenty-eight Mw≥6.4 strike-slip events) shows that SSDs are not correlated with structural maturity as previously suggested.