The 2014 Kefalonia earthquake sequence started on 26 January with the first main shock (M w 6.1) and aftershock activity extending over 35 km, much longer than expected from the causative fault segment. The second main shock (M w 6.0) occurred on 3 February on an adjacent fault segment, where the aftershock distribution was remarkably sparse, evidently encouraged by stress transfer of the first main shock. The aftershocks from the regional catalog were relocated using a 7-layer velocity model and station residuals, and their distribution evidenced two adjacent fault segments striking almost N-S and dipping to the east, in full agreement with the centroid moment tensor solutions, constituting segments of the Kefalonia Transform Fault (KTF). The KTF is bounded to the north by oblique parallel smaller fault segments, linking KTF with its northward continuation, the Lefkada Fault.

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An extensive search for repeating earthquakes was performed in the western Corinth Gulf by applying waveform cross-correlation on 22 000 earthquakes that occurred in 2008-2014. Event pairs with high correlation coefficient (CC ≥ 0.95) recorded by two or more stations are classified as multiplets of repeating events. The highly similar event pairs have typically interevent distances less than a quarter wavelength (∼150 m for a dominant frequency of 10 Hz) and are used to estimate the accuracy of the relocated catalogue. A detailed analysis of the spatio-temporal properties of the repeating sequences revealed two types of repeating events, namely, burst-like and continuous-type repeaters. Burst-like repeaters are widespread in the entire study area, mostly associated with seismic excitations located at depths between 5 and 9 km, triggered either by fluid intrusion or stress transfer. Their duration is short with high values of coefficient of variation in recurrence intervals (COV > 1) and high slip rates. The continuous-type repeaters, which last 1-7 yr, with COV ∼ 1 and slip rates almost 0.26 cm yr −1 , form a very narrow shallow north-dipping seismic zone at 10 km depth along the Psathopyrgos and Aigion faults. That kind of activity provides strong evidence for aseismic slip in the western Corinth Gulf and defines the boundary between brittle and ductile layers in the area.

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The Mineral Mountains are located east of Milford Valley (Figure 1), within the transition zone from the Basin and Range to Colorado Plateau physiographic provinces (Wannamaker et al., 2001). Geologically, the Mineral Mountains are dominated by an Oligocene-Miocene granitic batholith (Coleman & Walker, 1992). Additionally, there are Quaternary rhyolitic and basaltic flow deposits (Nielson et al., 1987). The most recent volcanism locates ∼4 km east of the Roosevelt Hot Springs and was active 0.8-0.5 Ma (Ward et al., 1978). Seismicity in the broader area is characterized by low rates of small magnitude earthquakes (Arabasz et al., 2007;Pankow et al., 2009). Within the Milford Valley, three distinct concentrations are observed when plotting recent seismicity (Figure 1) (Pankow et al., 2017), (a) earthquakes to the west clustered around a quarry and related to blasts, (b) a cluster of earthquakes near the Milford airport, in the region where the two largest local events occurred (Arabasz et al., 2016;Whidden & Pankow, 2012), and (c) seismicity in the Mineral Mountains, that has been characterized as a swarm-genic area (Zandt et al., 1982). Two local faults are mapped in the central Mineral Mountains. The Opal Mound fault is a normal fault that dips steeply to the east in the direction of the Mineral Mountains, not towards the basin as is typically observed in Basin and Range bounding faults (Brogan & Birkhahn, 1982). The Mag Lee fault is an east-west structure whose dip is not well constrained. While older studies indicate dipping to the south (Nielson et al., 1987;Ward et al., 1978), more recent studies indicate it dips to the north (Kirby et al., 2018).

The 18 March 2020 M w 5.7 Magna earthquake near Salt Lake City, Utah, offers a rare glimpse into the subsurface geometry of the Wasatch fault system-one of the world's longest active normal faults and a major source of seismic hazard in northern Utah. We analyze the Magna earthquake sequence and resolve oblique-normal slip on a shallow (30-35°) west-dipping fault at~9-to 12-km depth. Combined with near-surface geological observations of steep dip (~70°), our results support a curved, or listric, fault shape. High-precision aftershock locations show the activation of multiple, low-angle (<30-35°) structures, indicating the existence of a complicated fault system. Our observations constrain the deep structure of the Wasatch fault system and suggest that ground shaking in the Salt Lake City region in future Wasatch fault earthquakes may be higher than previously estimated. Plain Language Summary On 18 March 2020, a moment magnitude (M w) 5.7 earthquake occurred beneath Magna, Utah, a suburb of Salt Lake City. It was the largest earthquake in the Wasatch fault system in historical times, and shaking was felt throughout northern Utah. The mainshock and its aftershocks were located in the middle of a dense seismic network, generating a rare and valuable data set of strong ground accelerations from normal-faulting earthquakes. We analyzed the first~6 weeks of seismic data following the mainshock and found that the aftershocks formed a shallow-dipping planar structure at depths of 9-12 km, implying that this segment of the Wasatch fault zone has a curved shape. At the surface, it dips steeply to the west at~70°, but as the depth increases, the dip becomes progressively more shallow. Simulations of ground shaking from large earthquakes previously assumed that this fault segment was planar and steeply dipping (~50°) throughout the upper crust. Our observations suggest that the rupture area of future large earthquakes will be closer to the surface than previously thought, which would cause increased ground shaking in the Salt Lake City metropolitan area with its~1.2 million residents. Geological mapping and modeling of the WFZ finds near-surface dips of 45-90°on the SLCS (Bruhn et al., 1992); however, there are competing models for its subsurface structure under the Salt Lake ©2020. American Geophysical Union. All Rights Reserved.

On 8 June 2008 an earthquake of M w 6.4 took place in the northwestern part of Peloponnese, Greece. The main shock was felt in a wide area and caused appreciable damage along the main rupture area and particularly at the antipodal of the main shock epicenter fault edge, implying strongly unilateral rupture and stopping phase effects. Abundant aftershocks were recorded within an area of *50 km in length in the period 8 June 2008-end of 2014, by a sufficient number of stations that secure location accuracy because the regional network is adequately dense in the area. All the available phases from seismological stations in epicentral distances up to 140 km until the end of 2014 were used for relocation with the double difference technique and waveform cross-correlation. A quite clear 3-D representation is obtained for the aftershock zone geometry and dimensions, revealing the main rupture and the activated adjacent fault segments. SAR data are processed using Stanford Method for Persistent Scatterers (StaMPS) and a surface deformation map constructed based on PS point displacement for the coseismic period. A variable slip model, with maximum slip of *1.0 m located at the lower part of the rupture plane, is suggested and used for calculating the deformation field which was found in adequate agreement with geodetic measurements. With the same slip model the static stress changes were calculated evidencing possible triggering of the neighboring faults that were brought closer to failure. The data availability allowed monitoring the temporal variation of b values that after a continuous increase in the first 5 days, returned and stabilized to 1.0-1.1 in the following years. The fluctuation duration is considered as the equivalent time for fault healing, which appeared very short but in full accordance with the cessation of onto-fault seismicity.