Preprints
Filtering by Subject: Physical Sciences and Mathematics
Scientific and risk-reduction benefits of involving citizens in monitoring volcanic activity
Published: 2017-11-20
Subjects: Earth Sciences, Environmental Monitoring, Environmental Sciences, Geology, Physical Sciences and Mathematics, Volcanology
Citizen science involves volunteers, regardless of scientific background, in conducting scientific investigations. Although the extent of citizen involvement varies, the reported benefits of such activities include: the generation of new knowledge; increased public understanding of and confidence in science, and ‘real-time’ insights into rapidly evolving events such as natural hazards. In [...]
Seismic and structural characterization of a pre-salt rifted section: the Lagoa Feia Group, Campos Basin, offshore Brazil
Published: 2017-11-17
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Stratigraphy
The exploration of pre-salt offshore SE Brazil presents a multifaceted deep-water scenario that is bringing new challenges to seismic interpretation in offshore Brazilian exploration and production. Reservoirs in this domain are complex, heterogeneous with layered carbonates which makes accurate reservoir characterization very challenging. Our study here deals with the seismic characterization of [...]
Unravelling intrusion-induced forced fold kinematics and ground deformation using 3D seismic reflection data
Published: 2017-11-17
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics
Sills emplaced at shallow-levels are commonly accommodated by overburden uplift, producing forced folds. We examine ancient forced folds developed above saucer-shaped sills using 3D seismic reflection data from the Canterbury Basin, offshore SE New Zealand. Seismic-stratigraphic relationships indicate sill emplacement occurred incrementally over ~31 Myr between the Oligocene (~35–32 Ma) and Early [...]
Fault growth and interactions in a multiphase rift fault network: Horda Platform, Norwegian North Sea
Published: 2017-11-15
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure
Physical models predict that multiphase rifts that experience a change in extension direction between stretching phases will typically develop non-colinear normal fault sets. Furthermore, multiphase rifts will display a greater frequency and range of styles of fault interactions than single-phase rifts. Although these physical models have yielded useful information on the evolution of fault [...]
The 1902-3 eruptions of the Soufrière, St Vincent: impacts, relief and response
Published: 2017-11-15
Subjects: Earth Sciences, Physical Sciences and Mathematics, Volcanology
Retrospective analysis of the contemporary colonial and scientific records of a major explosive eruption of the Soufrière of St Vincent from 1902-1903 reveals how this significant and prolonged event presented challenges to the authorities charged with managing the crisis and its aftermath. In a small-island setting vulnerable to multiple hazards, the spatial footprint of the volcanic hazard and [...]
Punctuated Sediment Discharge During Early Pliocene Birth of the Colorado River: Evidence from Regional Stratigraphy, Sedimentology, and Paleontology
Published: 2017-11-14
Subjects: Earth Sciences, Physical Sciences and Mathematics, Stratigraphy
The Colorado River in the southwestern U.S. provides an excellent natural laboratory for studying the origins of a continent-scale river system, because deposits that formed prior to and during river initiation are well exposed in the lower river valley and nearby basinal sink. This paper presents a synthesis of regional stratigraphy, sedimentology, and micropaleontology from the southern Bouse [...]
A new global mode of Earth deformation: seasonal cycle detected
Published: 2017-11-14
Subjects: Earth Sciences, Environmental Monitoring, Environmental Sciences, Geophysics and Seismology, Hydrology, Oceanography and Atmospheric Sciences and Meteorology, Other Earth Sciences, Other Environmental Sciences, Other Oceanography and Atmospheric Sciences and Meteorology, Other Physical Sciences and Mathematics, Physical Sciences and Mathematics
We have detected a global mode of Earth deformation that is predicted by theory. Precise positioning of GPS sites distributed worldwide reveals that in February to March the northern hemisphere compresses (and the southern hemisphere expands), such that sites near the North Pole move downward by 3.0 mm, and sites near the equator are pulled northwards by 1.5 mm. The opposite pattern of [...]
Choice of optimal averaging radii for temporal GRACE gravity solutions, a comparison with GPS and satellite altimetry
Published: 2017-11-13
Subjects: Earth Sciences, Environmental Monitoring, Environmental Sciences, Geophysics and Seismology, Glaciology, Hydrology, Other Earth Sciences, Other Environmental Sciences, Physical Sciences and Mathematics
One of the initial challenges of the GRACE mission is to validate the accuracy of the time-variable gravity fields. These gravity fields contain both spatially correlated (systematic) and random noise and hence spatial averaging needs to be implemented. Before the fields may be interpreted, optimum averaging radii need to be determined through comparison with independent data. We compare time [...]
A comparison of GPS, VLBI and model estimates of ocean tide loading displacements
Published: 2017-11-13
Subjects: Civil and Environmental Engineering, Earth Sciences, Engineering, Environmental Sciences, Geophysics and Seismology, Other Civil and Environmental Engineering, Other Earth Sciences, Physical Sciences and Mathematics
In recent years, Ocean Tide Loading Displacements (OTLD) have been measured using the Global Positioning System (GPS) and Very Long Baseline Interferometry (VLBI). This study assesses the accuracy of GPS measurements of OTLD by comparison with VLBI measurements and estimates derived from numerical ocean tide models. A daily precise point positioning (PPP) analysis was carried out on ~11 years of [...]
GPS sidereal filtering: coordinate- and carrier-phase-level strategies
Published: 2017-11-13
Subjects: Civil and Environmental Engineering, Civil Engineering, Earth Sciences, Engineering, Other Civil and Environmental Engineering, Other Earth Sciences, Other Physical Sciences and Mathematics, Physical Sciences and Mathematics
Multipath error is considered one of the major errors affecting GPS observations. One can benefit from the repetition of satellite geometry approximately every sidereal day, and apply filtering to help minimize this error. For GPS data at 1 second interval processed using a double-difference strategy, using the day-to-day coordinate or phase residual autocorrelation determined with a 10 hour [...]
Basis functions for the consistent and accurate representation of surface mass loading
Published: 2017-11-13
Subjects: Applied Mathematics, Earth Sciences, Environmental Indicators and Impact Assessment, Environmental Monitoring, Environmental Sciences, Geophysics and Seismology, Numerical Analysis and Computation, Oceanography and Atmospheric Sciences and Meteorology, Other Earth Sciences, Other Environmental Sciences, Other Oceanography and Atmospheric Sciences and Meteorology, Other Physical Sciences and Mathematics, Physical Sciences and Mathematics
Inversion of geodetic site displacement data to infer surface mass loads has previously been demonstrated using a spherical harmonic representation of the load. This method suffers from the continent-rich, ocean-poor distribution of the geodetic data, coupled with the predominance of the continental load (water storage and atmospheric pressure) compared with the ocean bottom pressure (including [...]
Decreasing cloud cover drives the recent mass loss on the Greenland Ice Sheet
Published: 2017-11-13
Subjects: Atmospheric Sciences, Climate, Earth Sciences, Environmental Sciences, Glaciology, Meteorology, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
The Greenland Ice Sheet (GrIS) has been losing mass at an accelerating rate since the mid-1990s. This has been due to both increased ice discharge into the ocean and melting at the surface, with the latter being the dominant contribution. This change in state has been attributed to rising temperatures and a decrease in surface albedo. We show, using satellite data and climate model output, that [...]
Using filtered and semi-continuous high rate GPS for monitoring deformations
Published: 2017-11-13
Subjects: Civil and Environmental Engineering, Civil Engineering, Construction Engineering and Management, Earth Sciences, Engineering, Environmental Monitoring, Environmental Sciences, Geophysics and Seismology, Geotechnical Engineering, Other Civil and Environmental Engineering, Other Earth Sciences, Other Environmental Sciences, Other Physical Sciences and Mathematics, Physical Sciences and Mathematics, Structural Engineering
Multipath is a major sidereally-repeating error affecting precise GPS positioning and deformation monitoring. Because satellite-receiver geometry repeats almost exactly every sidereal day, filtering can reduce multipath in near-static situations. Here, we investigate how sidereal filtering can be used in a switched multi-antenna array system providing semi-continuous GPS data, which may be [...]
J2: an evaluation of new estimates from GPS, GRACE and load models compared to SLR
Published: 2017-11-13
Subjects: Earth Sciences, Environmental Monitoring, Environmental Sciences, Geophysics and Seismology, Other Earth Sciences, Other Environmental Sciences, Other Physical Sciences and Mathematics, Physical Sciences and Mathematics
Changes in J2, resulting from past and present changes in Earth’s climate, are traditionally observed by Satellite Laser ranging (SLR). Assuming an elastic Earth, it is possible to infer changes in J2 from changes in Earth’s shape observed by GPS. We compare estimates of non-secular J2 changes from GPS, SLR, GRACE and a load model. The GPS and SLR annual signals agree but are different (16%) to [...]
An examination of network RTK GPS services in Great Britain
Published: 2017-11-13
Subjects: Civil and Environmental Engineering, Civil Engineering, Construction Engineering and Management, Earth Sciences, Engineering, Environmental Monitoring, Environmental Sciences, Geophysics and Seismology, Other Civil and Environmental Engineering, Other Earth Sciences, Other Environmental Sciences, Other Physical Sciences and Mathematics, Physical Sciences and Mathematics
As of March 2009, network real-time kinematic (RTK) GPS surveying is available in Great Britain with the aid of two commercial service providers, Leica’s “SmartNet” and Trimble’s “VRS Now”, both of which rely largely on the Ordnance Survey’s “OS Net” network of around 120 continuously operating reference stations. With the aim of testing the performance of Network RTK under both ideal and [...]