Preprints
Filtering by Subject: Volcanology
Volcanic and Magmatic Studies Group Members Survey 2020
Published: 2020-07-24
Subjects: Earth Sciences, Physical Sciences and Mathematics, Volcanology
The Volcanic & Magmatic Studies Group (VMSG) is a joint Special Interest Group of the Geological Society of London and Mineralogical Society. In January 2020 we conducted an online questionnaire to establish if (and how) VMSG fulfils its mission to serve the volcanology, petrology and geochemistry community. The survey was distributed via the VMSG mailing list, publicised at the VMSG annual [...]
Rapid heat discharge during deep-sea eruptions generates megaplumes and disperses tephra
Published: 2020-07-16
Subjects: Earth Sciences, Fluid Dynamics, Geology, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Other Physical Sciences and Mathematics, Physical Sciences and Mathematics, Physics, Volcanology
Deep-marine volcanism drives Earth’s most energetic transfers of heat and mass between the crust and the oceans. Seafloor magmatic activity has been correlated in time with the appearance of massive enigmatic plumes of hydrothermal fluid, known as megaplumes, yet little is known of the primary source and intensity of the hydrothermal energy release that occurs during [...]
Turbulent flow effects in a slickwater fracture propagation in permeable rock
Published: 2020-06-18
Subjects: Earth Sciences, Environmental Sciences, Hydrology, Oil, Gas, and Energy, Physical Sciences and Mathematics, Volcanology
This work is devoted to an analysis of the near-tip region of a hydraulic fracture driven by slickwater in a permeable saturated rock. We consider a steady-state problem of a semi-infinite fracture propagating with constant velocity. The host rock is elastic and homogeneous, and fracture propagates according to linear elastic fracture mechanics. The fluid exchange between the fracture and [...]
Deformation controlled Long-Period seismicity in low cohesion volcanic sediments
Published: 2020-06-18
Subjects: Earth Sciences, Physical Sciences and Mathematics, Volcanology
Volcano seismicity is an important tool in remotely monitoring and forecasting activity at volcanoes around the world. Volcanic earthquakes show diverse spectral characteristics, with shallow Long Period (Low Frequency) seismicity and long duration tremor generally interpreted as indicators of fluid migration, and as potential precursors to eruption. Here we show that a common low-cohesion [...]
Heat does not physically flow in the ways assumed by greenhouse-warming theory
Published: 2020-06-06
Subjects: Climate, Earth Sciences, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics, Volcanology
Heat is currently defined as an amount of thermal energy flowing each second per unit area. Temperature is assumed to result from the net amount of heat flowing—the sum of all radiative forcings. Yet direct and unambiguous observations of Nature show that macroscopic temperature of solid matter results from a very broad spectrum of sub-microscopic oscillations of all the bonds holding matter [...]
Eruptive dynamics in Plinian silicic eruptions
Published: 2020-06-04
Subjects: Earth Sciences, Physical Sciences and Mathematics, Volcanology
Plinian eruptions are characterized by high magma discharge rates and pyroclastic material containing extraordinary large numbers of bubbles. Upon ascent to the surface magma decompresses and volatiles become supersaturated, causing bubbles to nucleate with a rate dependent on the degree of supersaturation. Thus, the conventional view is that the number of bubbles nucleating within the erupting [...]
Simultaneous fall and flow during pyroclastic eruptions: a novel proximal hybrid facies.
Published: 2020-05-24
Subjects: Earth Sciences, Physical Sciences and Mathematics, Volcanology
The deposits of Plinian and sub-Plinian eruptions provide critical insights into past volcanic events and inform numerical models that aim to mitigate against future hazards. However, pyroclastic deposits are often considered from either a fallout or pyroclastic density current (PDC) perspective, with little attention given to facies exhibiting characteristics of both processes. Such hybrid units [...]
Upper mantle mush zones beneath low melt flux ocean island volcanoes: insights from Isla Floreana, Galápagos
Published: 2020-05-24
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics, Volcanology
The physicochemical characteristics of sub-volcanic magma storage regions have important implications for magma system dynamics and pre-eruptive behaviour. The architecture of magma storage regions located directly above high buoyancy flux mantle plumes (such as Kīlauea, Hawai’i and Fernandina, Galápagos) are relatively well understood. However, far fewer constraints exist on the nature of magma [...]
Holocene tephrochronology of Kerguelen Archipelago, Subantarctic Indian Ocean
Published: 2020-05-20
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics, Sedimentology, Stratigraphy, Volcanology
Up to now, no geochemical or geochronological data has been published about Holocene volcanic activity on the Kerguelen Archipelago. Here we present the first continuous Holocene chronology of volcanic eruptions on the archipelago. We compared sedimentological, geochronological and geochemical data from two lake sediment cores taken in two different depocenters of Lake Armor, located ca. 70 km [...]
A radial hydraulic fracture with pressure-dependent leak-off
Published: 2020-05-06
Subjects: Earth Sciences, Environmental Sciences, Hydrology, Oil, Gas, and Energy, Physical Sciences and Mathematics, Volcanology
This paper investigates the problem of a radial (or penny-shaped) hydraulic fracture propagating in a permeable reservoir. In particular, we consider the fluid exchange between the crack and ambient porous media as a pressure-dependent process. In most of the existing models, the fluid exchange process is represented as one-dimensional pressure-independent leak-off described by Carters law. We [...]
Interferometric Processing of ScanSAR Data Using Stripmap Processor: New Insights from Coregistration
Published: 2020-04-14
Subjects: Aerospace Engineering, Civil and Environmental Engineering, Computer Engineering, Earth Sciences, Electrical and Computer Engineering, Engineering, Geology, Geophysics and Seismology, Glaciology, Hydrology, Mining Engineering, Other Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure, Volcanology
Processing scanning synthetic aperture radar (ScanSAR) data using a stripmap processor, which is called full-aperture processing, has been the choice of many researchers. ScanSAR data are known to require very high azimuth coregistration precision which is usually achieved by a geometrical coregistration followed by a spectral diversity coregistration on the ScanSAR burst. However, for [...]
Interferometry with ALOS-2 full-aperture ScanSAR data
Published: 2020-04-14
Subjects: Aerospace Engineering, Civil and Environmental Engineering, Earth Sciences, Electrical and Computer Engineering, Engineering, Geology, Geophysics and Seismology, Glaciology, Mining Engineering, Other Engineering, Physical Sciences and Mathematics, Physics, Tectonics and Structure, Volcanology
Advanced Land Observing Satellite-2 (ALOS-2) is designed to routinely acquire both scanning synthetic aperture radar (ScanSAR) and stripmap data. In this paper, we present a special multiband bandpass filter (MBF) to remove azimuth nonoverlap spectra for the interferometric processing of ALOS-2 full-aperture ScanSAR product. As required by the MBF, we estimate the important ScanSAR system [...]
InSAR Time Series Analysis of L-band Wide- Swath SAR Data Acquired by ALOS-2
Published: 2020-04-12
Subjects: Aerospace Engineering, Civil and Environmental Engineering, Earth Sciences, Electrical and Computer Engineering, Engineering, Environmental Sciences, Geology, Geomorphology, Geophysics and Seismology, Glaciology, Hydrology, Mining Engineering, Other Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure, Volcanology
Operating at L-band (~24 cm wavelength) in wide-swath modes is one of the characteristics of the new and next generation satellite synthetic aperture radar (SAR) missions. After 3 years of operation, the Japan Aerospace Exploration Agency Advanced Land Observing Satellite-2 (ALOS-2) satellite has acquired a wealth of L-band wide-swath SAR data over many areas using its ScanSAR mode. We present [...]
Measuring Azimuth Deformation With L-Band ALOS-2 ScanSAR Interferometry
Published: 2020-04-06
Subjects: Aerospace Engineering, Civil and Environmental Engineering, Computational Engineering, Computer Engineering, Earth Sciences, Electrical and Computer Engineering, Engineering, Geology, Geomorphology, Geophysics and Seismology, Glaciology, Hydrology, Mining Engineering, Other Earth Sciences, Physical Sciences and Mathematics, Signal Processing, Tectonics and Structure, Volcanology
We analyze the methods for measuring azimuth deformation with the L-band Advanced Land Observing Satellite-2 (ALOS-2) scanning synthetic aperture radar (ScanSAR) interferometry. To implement the methods, we extract focused bursts from the ALOS-2 full-aperture product, which is the only product available for ScanSAR interferometry at present. The extracted bursts are properly processed to measure [...]
Estimating Azimuth Offset With Double-Difference Interferometric Phase: The Effect of Azimuth FM Rate Error in Focusing
Published: 2020-04-06
Subjects: Aerospace Engineering, Civil and Environmental Engineering, Earth Sciences, Electrical and Computer Engineering, Engineering, Environmental Sciences, Geology, Geomorphology, Geophysics and Seismology, Glaciology, Hydrology, Mining Engineering, Other Earth Sciences, Physical Sciences and Mathematics, Physics, Tectonics and Structure, Volcanology
Estimating azimuth offset with double-difference interferometric (DDI) phase, which is called multiple-aperture interferometric synthetic aperture radar (InSAR) or spectral diversity, is increasingly used in recent years to measure azimuth deformation or to accurately coregister a pair of InSAR images. We analyze the effect of frequency modulation (FM) rate error in focusing on the DDI phase with [...]