Supplemental Material: How similar was the 1983 Mw 6.9 Borah Peak earthquake rupture to its surface-faulting predecessors along the northern Lost River fault zone (Idaho, USA)?

Text S1: Bayesian (OxCal) models for northern Lost River fault zone trench sites. Text S2: Bulk sediment analysis and charcoal identification; Text S3: Luminescence geochronology. Table S1: Description of stratigraphic units at the Sheep Creek trench. Table S2: Description of stratigraphic units at the Arentson Gulch trench. Figure S1: Photomosaics and large-format trench logs for the Sheep Creek trench. Figure S2: Photomosaics and large-format trench logs for the Arentson Gulch trench. Figure S3: Sheep Creek and Arentson Gulch vertical displacement measurements. Figure S4: Fault bend angles along the northern Lost River fault zone. Figure S5: Photographs of the Sheep Creek and Arentson Gulch trench sites. Figure S6: Probability density functions for Lost River fault zone ruptures.

Supplemental Material: How similar was the 1983 Mw 6.9 Borah Peak earthquake rupture to its surface-faulting predecessors along the northern Lost River fault zone (Idaho, USA)?

Text S1: Bayesian (OxCal) models for northern Lost River fault zone trench sites. Text S2: Bulk sediment analysis and charcoal identification; Text S3: Luminescence geochronology. Table S1: Description of stratigraphic units at the Sheep Creek trench. Table S2: Description of stratigraphic units at the Arentson Gulch trench. Figure S1: Photomosaics and large-format trench logs for the Sheep Creek trench. Figure S2: Photomosaics and large-format trench logs for the Arentson Gulch trench. Figure S3: Sheep Creek and Arentson Gulch vertical displacement measurements. Figure S4: Fault bend angles along the northern Lost River fault zone. Figure S5: Photographs of the Sheep Creek and Arentson Gulch trench sites. Figure S6: Probability density functions for Lost River fault zone ruptures.

Surface Slip Distribution and Earthquake Rupture Model of the Fuyun Fault, China, Based on High-Resolution Topographic Data

The characteristics of earthquake surface ruptures, such as geometry, slip distribution, and coseismic deformation, contain important information about the earthquake rupture process, and so investigations and analyses of earthquake surface rupture have played a crucial role in modern earthquake hazard studies, especially with the increasing availability of high-resolution topographic and imagery data for tectono-geomorphic interpretation. In this study, we use Structure from Motion (SfM) photogrammetry to build a 1 m resolution digital elevation model (DEM) of the fault and combine this with filed observations to map the surface ruptures of the 1931 M8.0 Fuyun earthquake, China. These high-resolution topographic data enable to identify and measure the displaced gullies, and so the rupture locations and along-strike slip distribution are obtained in detail. Four paleoearthquake events are identified through the offset cluster characteristics. The coseismic offset of the 1931 Fuyun earthquake is extracted from the offset distribution, which shows four continuous undulations along the fault strike, corresponding to the four segments of surface rupture. Moreover, a high offset gradient is observed in the step area connected by the rupture segment. These findings, combined with the width and bending angle of the step area at the joint of the rupture segment, indicate that the 1931 Fuyun earthquake was a cascade rupture formed by four rupture segments. This study expands the available offset measurement data of Fuyun fault and confirms the applicability of high-resolution topographic data to active tectonic research.

Usefulness of Coulomb Static Stress Changes in Earthquake Hazard Studies: An Example from the Lake Van Area, Eastern Turkey

It has been globally documented over different tectonic environments that Coulomb static stress changes caused by a mainshock can promote or demote stresses along the neighboring faults and thus triggers or delays following seismicity. In the present study Coulomb stress changes of the earthquakes in the Lake Van area are calculated using available data and the likely source faults. The calculated stress change maps demonstrate that the large earthquakes in the Lake Area are mostly stressed by the preceding earthquakes, suggesting earthquake rupture interactions. It is further suggested that Coulomb stress maps could be used for constraining the likely locations of the future large earthquakes and in the earthquake hazard mitigation studies.

Marine forearc structure of eastern Java and its role in the 1994 Java tsunami earthquake

We resolve a previously unrecognized shallow subducting seamount from a re-processed multichannel seismic profile crossing the 1994 Mw 7.8 Java tsunami earthquake rupture area. Seamount subduction occurs where the overriding plate experiences uplift by lateral shortening and vertical thickening. Pronounced back-thrusting at the landward slope of the forearc high and the formation of splay faults branching off the landward flank of the subducting seamount are observed. The location of the seamount in relation to the 1994 earthquake hypocentre and its co-seismic slip model suggests that the seamount acted as a seismic barrier to the up-dip co-seismic rupture propagation of this moderate-size earthquake.