Preprints
Filtering by Subject: Geophysics and Seismology
P and S tomography using normal-mode and surface waves data with a neighbourhood algorithm
Published: 2017-11-03
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Traditionally P- and S-wave tomography has been based on the inversion of data that are sensitive to the desired Earth structure, and model covariance is estimated from imperfect resolution and data error propagation. This analysis ignores the usually large null-spaces, and hence the significant non-uniqueness of the solution encountered in seismic tomography problems. Here we perform a model [...]
Locating Seismicity on the Arctic Plate Boundary Using Multiple-Event Techniques and Empirical Signal Processing
Published: 2017-11-03
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The oceanic boundary separating the Eurasian and North American plates between 70 and 84 degrees North hosts large earthquakes which are well recorded teleseismically, and many more seismic events at far lower magnitudes that are well recorded only at regional distances. Existing seismic bulletins have considerable spread and bias resulting from limited station coverage and deficiencies in the [...]
The Applicability of Incoherent Array Processing to IMS Seismic Arrays
Published: 2017-11-02
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The seismic arrays of the International Monitoring System (IMS) for the Comprehensive Nuclear-Test-Ban Treaty (CTBT) are highly diverse in size and configuration, with apertures ranging from under 1 km to over 60 km. Large and medium aperture arrays with large inter-site spacings complicate the detection and estimation of high-frequency phases lacking coherence between sensors. Pipeline detection [...]
The 11 October 2010 Novaya Zemlya Earthquake: Implications for Velocity Models and Regional Event Location
Published: 2017-11-02
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Characterizing the seismicity of Novaya Zemlya and the surrounding Arctic seas requires accurate event‐location estimates. Low‐magnitude events in this region are currently observed only by a small number of stations in the European Arctic, with a large azimuthal gap, making the accuracy of regional velocity models all the more important. Regional travel‐time calibration is difficult given the [...]
Accurate relative location estimates for the North Korean nuclear tests using empirical slowness corrections
Published: 2017-11-01
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Declared North Korean nuclear tests in 2006, 2009, 2013 and 2016 were observed seismically at regional and teleseismic distances. Waveform similarity allows the events to be located relatively with far greater accuracy than the absolute locations can be determined from seismic data alone. There is now significant redundancy in the data given the large number of regional and teleseismic stations [...]
Illuminating the seismicity pattern of the October 8, 2005, M = 7.6 Kashmir earthquake aftershocks
Published: 2017-11-01
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The M=7.6 October 8, 2005, Kashmir earthquake generated thousands of aftershocks. Existing catalogs are coarse, omitting data from key stations and not correcting bias. We target arrivals on unexploited regional stations with optimized signal processing. A multiple event Bayesian relocation results in far more structured clusters of seismicity. All arrival data for the Bayesloc program is [...]
A systematic study of earthquake detectability using Sentinel-1 Interferometric Wide-Swath data
Published: 2017-11-01
Subjects: Earth Sciences, Geophysics and Seismology, Other Earth Sciences, Physical Sciences and Mathematics
The Sentinel-1 mission comprises two synthetic aperture radar satellites, each with a 12 day orbital repeat, orbiting 6 days apart within a narrow tube. The mission design promises the ability to respond quickly to earthquakes with InSAR, and to facilitate production of interferograms with good interferometric correlation globally. We report on our efforts to study global seismicity using [...]
Geological applications of digital terrain analysis
Published: 2017-11-01
Subjects: Earth Sciences, Geochemistry, Geographic Information Sciences, Geography, Geology, Geomorphology, Geophysics and Seismology, Physical Sciences and Mathematics, Remote Sensing, Social and Behavioral Sciences, Spatial Science, Tectonics and Structure, Volcanology
Editorial to the IJGIS Special Issue on "Geological applications of digital terrain analysis". In this volume, the modern advances in the field of geological terrain analysis are presented, while emphasis is given to the quantitative analysis of modern datasets.
Determining geophysical responses from burials in graveyards and cemeteries
Published: 2017-10-31
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Graveyards and cemeteries around the world are increasingly designated as full. There is therefore a requirement to identify vacant spaces for new burials or to identify existing ones to exhume and then re-inter if necessary. Geophysical methods offer a potentially non-invasive target detection solution; however, there has been limited research to identify optimal geophysical detection methods [...]
Electromagnetic torques in the core and resonant excitation of decadal polar motion
Published: 2017-10-31
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Motion of the rotation axis of the Earth contains decadal variations with amplitudes on the order of 10 mas. The origin of these decadal polar motions is unknown. A class of rotational normal modes of the core–mantle system termed torsional oscillations are known to affect the length of day (LOD) at decadal periods and have also been suggested as a possible excitation source for the observed [...]
A general model for the helical structure of geophysical flows in channel bends
Published: 2017-10-31
Subjects: Civil and Environmental Engineering, Earth Sciences, Engineering, Environmental Engineering, Environmental Sciences, Fluid Dynamics, Geology, Geomorphology, Geophysics and Seismology, Hydrology, Life Sciences, Natural Resources and Conservation, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Oil, Gas, and Energy, Other Physical Sciences and Mathematics, Physical Sciences and Mathematics, Physics, Risk Analysis, Sedimentology
Meandering channels host geophysical flows that form the most extensive sediment transport systems on Earth (i.e. rivers and submarine channels). Measurements of helical flow structures in bends have been key to understanding sediment transport in rivers. Turbidity currents differ from rivers in both density and velocity profiles. These differences, and the lack of field measurements of turbidity [...]
Spatially explicit spectral analysis of point clouds and geospatial data
Published: 2017-10-30
Subjects: Civil and Environmental Engineering, Civil Engineering, Computer Sciences, Earth Sciences, Engineering, Geomorphology, Geophysics and Seismology, Numerical Analysis and Scientific Computing, Physical Sciences and Mathematics, Sedimentology
The increasing use of spatially explicit analyses of high-resolution spatially distributed data (imagery and point clouds) for the purposes of characterising spatial heterogeneity in geophysical phenomena necessitates the development of custom analytical and computational tools. In recent years, such analyses have become the basis of, for example, automated texture characterisation and [...]
Seismic Interpretation of Sill-Complexes in Sedimentary Basins: The ‘Sub-Sill Imaging Problem’
Published: 2017-10-30
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Physical Sciences and Mathematics, Volcanology
Application of 3D-seismic reflection-data to igneous systems in sedimentary basins has led to a revolution in the understanding of mafic sill-complexes. However, there is considerable uncertainty on how geometries and architecture of sill complexes within the subsurface relates those imaged in seismic reflection-data. To provide constraints on how sill complexes in seismic data should be [...]
On the scales of dynamic topography in whole-mantle convection models - preprint version
Published: 2017-10-29
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Mantle convection shapes Earths surface by generating dynamic topography. Observational constraints and regional convection models suggest that surface topography could be sensitive to mantle flow for wavelengths as short as 1,000 km and 250 km, respectively. At these spatial scales, surface processes including sedimentation and relative sea-level change occur on million year timescales. [...]
A Bayesian Method to Quantify Azimuthal Anisotropy Model Uncertainties: Application to Global Azimuthal Anisotropy in the Upper Mantle and Transition Zone
Published: 2017-10-28
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Seismic anisotropy is a powerful tool to constrain mantle deformation, but its existence in the deep upper mantle and topmost lower mantle is still uncertain. Recent results from higher mode Rayleigh waves have, however, revealed the presence of 1% azimuthal anisotropy between 300 km and 800 km depth, and changes in azimuthal anisotropy across the mantle transition zone boundaries. This has [...]