Preprints
Filtering by Subject: Geophysics and Seismology
The crisis of a paradigm. A methodological interpretation of Tohoku and Fukushima catastrophe
Published: 2017-12-04
Subjects: Earth Sciences, Environmental Studies, Geophysics and Seismology, Physical Sciences and Mathematics, Social and Behavioral Sciences, Tectonics and Structure
The 2011 Japanese disaster often presented as a ‘new Chernobyl’ accumulated the effects of earthquake, tsunami and of the subsequent nuclear accident at Fukushima. In the light of this disaster, we review methodological rea- sons both from geophysical and philosophical perspectives that lead the scientific and technological communities to flawed conclusions, prime cause of the disaster. The [...]
The role of coseismic Coulomb stress changes in shaping the hard-link between normal fault segments
Published: 2017-11-27
Subjects: Earth Sciences, Geology, Geomorphology, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
The mechanism and evolution of fault linkage is important in the growth and development of large faults. Here we investigate the role of coseismic stress changes in shaping the hard-links between parallel normal fault segments (or faults), by comparing numerical models of the Coulomb stress change from simulated earthquakes on two en echelon fault segments to natural observations of hard-linked [...]
Rupture Process during the Mw 8.1 2017 Chiapas Mexico Earthquake: Shallow Intraplate Normal Faulting by Slab Bending
Published: 2017-11-24
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
A seismic source model for the Mw 8.1 2017 Chiapas, Mexico, earthquake was constructed by kinematic waveform inversion using globally observed teleseismic waveforms, suggesting that the earthquake was a normal-faulting event on a steeply dipping plane, with the major slip concentrated around a relatively shallow depth of 28 km. The modeled rupture evolution showed unilateral, down-dip propagation [...]
Numerical solution of a non-linear conservation law applicable to the interior dynamics of partially molten planets
Published: 2017-11-21
Subjects: Applied Mathematics, Computer Sciences, Earth Sciences, Fluid Dynamics, Geophysics and Seismology, Numerical Analysis and Computation, Numerical Analysis and Scientific Computing, Physical Sciences and Mathematics, Physics
The energy balance of a partially molten rocky planet can be expressed as a non-linear diffusion equation using mixing length theory to quantify heat transport by both convection and mixing of the melt and solid phases. Crucially, in this formulation the effective or eddy diffusivity depends on the entropy gradient, dS/dr, as well as entropy itself. First we present a simplified model with [...]
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 [...]
A new global mode of Earth deformation: seasonal cycle detected
Published: 2017-11-13
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 [...]
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 [...]
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 [...]
Ocean tide loading and relative GNSS in the British Isles
Published: 2017-11-13
Subjects: Civil and Environmental Engineering, Earth Sciences, Engineering, Environmental Monitoring, Environmental Sciences, Geophysics and Seismology, Oceanography and Atmospheric Sciences and Meteorology, Other Civil and Environmental Engineering, Other Earth Sciences, Other Environmental Sciences, Other Oceanography and Atmospheric Sciences and Meteorology, Other Physical Sciences and Mathematics, Physical Sciences and Mathematics
Ocean tide loading (OTL) affects all parts of the British Isles to varying degree, causing peak-to-peak vertical displacements of up to 13 cm in South-West England over semi-diurnal and diurnal timescales. Lateral displacements are typically around one-third of the magnitude of vertical displacements at a point, so are also considerable for carrier phase GNSS surveying. Using a recent numerical [...]
Increased ice loading in the Antarctic Peninsula since the 1850s and its effect on Glacial Isostatic Adjustment
Published: 2017-11-13
Subjects: Climate, Earth Sciences, Environmental Monitoring, Environmental Sciences, Geophysics and Seismology, Glaciology, Oceanography and Atmospheric Sciences and Meteorology, Other Earth Sciences, Other Environmental Sciences, Physical Sciences and Mathematics
Antarctic Peninsula (AP) ice core records indicate significant accumulation increase since 1855, and any resultant ice mass increase has the potential to contribute substantially to present-day Glacial Isostatic Adjustment (GIA). We derive empirical orthogonal functions from climate model output to infer typical spatial patterns of accumulation over the AP and, by combining with ice core records, [...]
Computationally Efficient Tsunami Modelling on Graphics Processing Units (GPU)
Published: 2017-11-13
Subjects: Applied Mathematics, Civil and Environmental Engineering, Civil Engineering, Computer Sciences, Earth Sciences, Engineering, Environmental Sciences, Geophysics and Seismology, Hydraulic Engineering, Numerical Analysis and Computation, Numerical Analysis and Scientific Computing, Other Civil and Environmental Engineering, Other Earth Sciences, Other Environmental Sciences, Physical Sciences and Mathematics
Tsunamis generated by earthquakes commonly propagate as long waves in the deep ocean and develop into sharp-fronted surges moving rapidly towards the coast in shallow water, which may be effectively simulated by hydrodynamic models solving the nonlinear shallow water equations (SWEs). However, most of the existing tsunami models suffer from long simulation time for large-scale real-world [...]