Mobile laser scans of vine rows deformed by the South Napa earthquake record shallow fault slip that does not breach the surface.

Deformation associated with plate convergence at subduction zones is accommodated by a complex system involving fault slip and viscoelastic flow. These processes have proven difficult to disentangle. The 2010 Mw 8.8 Maule earthquake occurred close to the Chilean coast within a dense network of continuously recording Global Positioning System stations, which provide a comprehensive history of surface strain. We use these data to assemble a detailed picture of a structurally controlled megathrust fault frictional patchwork and the three-dimensional rheological and time-dependent viscosity structure of the lower crust and upper mantle, all of which control the relative importance of afterslip and viscoelastic relaxation during postseismic deformation. These results enhance our understanding of subduction dynamics including the interplay of localized and distributed deformation during the subduction zone earthquake cycle.

The Mw 6.4 and Mw 7.1 Ridgecrest earthquake sequence occurred on 4 and 5 July 2019 within the eastern California shear zone of southern California. Both events produced extensive surface faulting and ground deformation within Indian Wells Valley and Searles Valley. In the weeks following the earthquakes, more than six dozen scientists from government, academia, and the private sector carefully documented the surface faulting and ground-deformation features. As of December 2019, we have compiled a total of more than 6000 ground observations; approximately 1500 of these simply note the presence or absence of fault rupture or ground failure, but the remainder include detailed descriptions and other documentation, including tens of thousands of photographs. More than 1100 of these observations also include quantitative field measurements of displacement sense and magnitude. These field observations were supplemented by mapping of fault rupture and ground-deformation features directly in the field as well as by interpreting the location and extent of surface faulting and ground deformation from optical imagery and geodetic image products. We identified greater than 68 km of fault rupture produced by both earthquakes as well as numerous sites of ground deformation resulting from liquefaction or slope failure. These observations comprise a dataset that is fundamental to understanding the processes that controlled this earthquake sequence and for improving earthquake hazard estimates in the region. This article documents the types of data collected during postearthquake field investigations, the compilation effort, and the digital data products resulting from these efforts.

Abstract:We describe a prototype compact mobile laser scanning system that may be operated from a backpack or unmanned aerial vehicle. The system is small, self-contained, relatively inexpensive, and easy to deploy. A description of system components is presented, along with the initial calibration of the multi-sensor platform. The first field tests of the system, both in backpack mode and mounted on a helium balloon for real-world applications are presented. For both field tests, the acquired kinematic LiDAR data are compared with highly accurate static terrestrial laser scanning point clouds. These initial results show that the vertical accuracy of the point cloud for the prototype system is approximately 4 cm (1σ) in balloon mode, and 3 cm (1σ) in backpack mode while horizontal accuracy was approximately 17 cm (1σ) for the balloon tests. Results from selected study areas on the Sacramento River Delta and San Andreas Fault in California demonstrate system performance, deployment agility and flexibility, and potential for operational production of high density and highly accurate point cloud data. Cost and production rate trade-offs place this system in the niche between existing airborne and tripod mounted LiDAR systems.

Afterslip hazard map of the Browns Valley neighborhood and surrounding area. A detailed map explanation is presented on the following page. vi Caption for map on previous page: Levels of Afterslip Hazard for the Browns Valley Neighborhood, City of Napa, California: All fault traces shown on this map face potential future earthquake fault surface rupture hazard and other earthquake-related hazards such as shaking, liquefaction, and landslides; these hazards are treated separately in other publications and maps from CGS and USGS (with preliminary updates provided in this report). For all levels of afterslip hazard, the afterslip amount that is measured 90 days after the earthquake can be expected to as much as double by 10 years after the earthquake (less than double is also possible). Red Fault Trace-High level of afterslip hazard; very likely to experience more than 15 cm of afterslip during the 3 years after the earthquake. (Red is intentionally included, even though none is indicated on this map.) Yellow Fault Trace-Moderate level of afterslip hazard; likely to experience less than 15 cm, but more than 5 cm, of afterslip during the 3 years after the earthquake. (Additional afterslip accumulation is likely to gradually accumulate an additional 5 cm during the 10 years after the earthquake and an additional 5 cm 30 years after the earthquake.) Green Fault Trace-Low level of afterslip hazard; very unlikely to experience more than 5 cm of afterslip during the 3 years after the earthquake. (Faults that experienced <10 cm of coseismic offset and <5 cm of afterslip within the 3 months after the earthquake are included in this category. Some faults or lineaments shown as green had no measurable coseismic slip or afterslip associated with the August 24, 2014, earthquake. Faults and lineaments of several categories are shown for completeness. Some are previously mapped strands (U.S. Geological Survey and California Geological Survey, 2006); others represent preliminary mapping based on a combination of imagery interpretation and field mapping that has taken place since the August 24, 2014, earthquake. All of the faults and/or imagery lineaments shown as heavy green lines on this map may be considered to have a low level of afterslip hazard. Subsequent ongoing mapping, that is, work still in progress, may reveal that certain lineaments shown here are not actually faults.) Map orientation: North direction is toward top of map.

Earthquake early warning's (EEW) fundamental promise is that earthquakes can be rapidly detected so that people and systems can be alerted to take protective action before shaking arrives at their location (Heaton, 1985). In order to maximize warning time and to minimize the population not receiving sufficient warning, EEW requires a dense sensor network so that earthquakes can be detected closest to wherever they may nucleate. The locations where earthquakes nucleate and where people reside, however, might be quite removed from one another. This requirement for dense sensor networks combined with the high cost of expensive scientific-grade sensors currently limits EEW systems to wealthy countries (Allen & Melgar, 2019). Alternatively, a new generation of low-cost accelerometer and geodetic sensors (Cochran, 2018) could make EEW generally accessible. In particular, utilizing smartphones, including via crowd-sourcing, is a potentially transformative way to provide EEW (

BackgroundThe weight of evidence suggests that women who freely choose to terminate a pregnancy are unlikely to experience significant mental health risks, however some studies have documented psychological distress in the form of posttraumatic stress disorder and depression in the aftermath of termination. Choice of anaesthetic has been suggested as a determinant of outcome. This study compared the effects of local anaesthesia and intravenous sedation, administered for elective surgical termination, on outcomes of pain, cortisol, and psychological distress.Methods155 women were recruited from a private abortion clinic and state hospital (mean age: 25.4 ± 6.1 years) and assessed on various symptom domains, using both clinician-administered interviews and self-report measures just prior to termination, immediately post-procedure, and at 1 month and 3 months post-procedure. Morning salivary cortisol assays were collected prior to anaesthesia and termination.ResultsThe group who received local anaesthetic demonstrated higher baseline cortisol levels (mean = 4.7 vs 0.2), more dissociative symptoms immediately post-termination (mean = 14.7 vs 7.3), and higher levels of pain before (mean = 4.9 vs 3.0) and during the procedure (mean = 8.0 vs 4.4). However, in the longer-term (1 and 3 months), there were no significant differences in pain, psychological outcomes (PTSD, depression, self-esteem, state anxiety), or disability between the groups. More than 65% of the variance in PTSD symptoms at 3 months could be explained by baseline PTSD symptom severity and disability, and post-termination dissociative symptoms. Of interest was the finding that pre-procedural cortisol levels were positively correlated with PTSD symptoms at both 1 and 3 months.ConclusionHigh rates of PTSD characterise women who have undergone surgical abortions (almost one fifth of the sample meet criteria for PTSD), with women who receive local anaesthetic experiencing more severe acute reactions. The choice of anesthetic, however, does not appear to impact on longer-term psychiatric outcomes or functional status.

Poor knowledge of how faults slip and distribute deformation in the shallow crust hinders efforts to mitigate hazards where faults increasingly intersect with the expanding global population at Earth's surface. Here we analyze two study sites along the 2014 M 6.0 South Napa, California, earthquake rupture, each dominated by either co-or post-seismic shallow fault slip. We combine mobile laser scanning (MLS), active-source seismic tomography, and finite element modeling to investigate how deformation rate and mechanical properties of the shallow crust affect fault behavior. Despite four orders-of-magnitude difference in the rupture velocities, MLS-derived shear strain fields are remarkably similar at the two sites and suggest deceleration of the co-seismic rupture near Earth's surface. Constrained by the MLS and seismic data, finite element models indicate shallow faulting is more sensitive to lithologic layering and plastic yielding than to the presence of fault compliant zones (i.e., regions surrounding faults with reduced stiffness). Although both elastic and elastoplastic models can reproduce the observed surface displacement fields within the uncertainty of MLS data, elastoplastic models likely provide the most reliable representations of subsurface fault behavior, as they produce geologically reasonable stress states and are consistent with field, geodetic, and seismological observations. strain within compliant zones 30,31 . Such deformation may arise from mechanisms of plastic yielding, for which evidence exists in paleoseismic trenches 32,33 . Although gravitational effects in layered media, including the acceleration of viscoelastic relaxation at long wavelengths and attenuation of the overall vertical displacement field, become important at length scales greater than several elastic plate thicknesses and/or over time periods much greater than the relaxation time, the effect on strains is negligible in the near-field and within a single earthquake cycle [34][35][36][37][38] .Relatively unstudied factors that may affect near-field deformation include layered elastic properties 39,40 and deformation rate (e.g., co-seismic versus post-seismic slip) 41,42 . Without greater confidence in how these proposed factors affect faulting near Earth's surface, we cannot reliably use the results of near-field geodetic analyses to infer shallow deformation, nor can we formulate models to predict fault slip and deformation in future events. Scientific RepoRtS |(2020) 10:5031 | https://doi.www.nature.com/scientificreports www.nature.com/scientificreports/ zone surrounding the fault. The corresponding surface deformation fields, however, do not obviously respond to these distinct elastic structures. In addition, the compliant zone width at Saintsbury (Fig. 2f) is nearly twice that of the observed shear zone (Fig. 2d), further indicating that the compliant zone does not strictly control the strain distribution. Our estimate of compliant zone width represents a minimum constraint 28 , since surveys covering the greater Napa ...