Volcano Deformation And Subdaily Gps Products

Thesis (Ph.D.) University of Alaska Fairbanks, 2012Volcanic unrest is often accompanied by hours to months of deformation of the ground that is measurable with high-precision GPS. Although GPS receivers are capable of near continuous operation, positions are generally estimated for daily intervals, which I use to infer characteristics of a volcano's plumbing system. However, GPS based volcano geodesy will not be useful in early warning scenarios unless positions are estimated at high rates and in real time. Visualization and analysis of dynamic and static deformation during the 2011 Tohokuoki earthquake in Japan motivates the application of high-rate GPS from a GPS seismology perspective. I give examples of dynamic seismic signals and their evolution to the final static offset in 30 s and 1 s intervals, which demonstrates the enhancement of subtle rupture dynamics through increased temporal resolution. This stresses the importance of processing data at recording intervals to minimize signal loss. Deformation during the 2009 eruption of Redoubt Volcano, Alaska, suggested net deflation by 0.05 km³ in three distinct phases. Mid-crustal aseismic precursory inflation began in May 2008 and was detected by a single continuous GPS station about 28 km NE of Redoubt. Deflation during the explosive and effusive phases was sourced from a vertical ellipsoidal reservoir at about 7-11.5 km. From this I infer a model for the temporal evolution of a complex plumbing system of at least 2 sources during the eruption. Using subdaily GPS positioning solutions I demonstrate that plumes can be detected and localized by utilizing information on phase residuals. The GPS network at Bezymianny Volcano, Kamchatka, records network wide subsidence at rapid rates between 8 and 12 mm/yr from 2005-2010. I hypothesize this to be caused by continuous deflation of a ~30 km deep sill under Kluchevskoy Volcano. Interestingly, 1-2 explosive events per year cause little to no deformation at any site other than the summit site closest to the vent. I derive evidence for a very shallow source, likely within the edifice. This work shows that network design and individual plumbing system characteristics affect the ability to detect motion on subdaily and even weekly time scales, which stresses the importance of network scale considerations

Interaction Room - Eine Methode zur Förderung der Wertorientierung in Planung und Requirements Engineering von Informationssystemen

Software wird immer wichtiger in unserer Gesellschaft, trotzdem dauern IT-Projekte länger und werden teurer, als ursprünglich geplant, sie verfehlen ihre funktionalen und qualitativen Ziele oder werden vorzeitig abgebrochen. Durch inhärente Ungewissheit, Komplexität und mangelnde Wertorientierung wird eine realistische Projektplanung für die Entwicklung von Informationssystemen erschwert. Auf Basis eines unzureichenden Verständnisses über Anforderungen, Risiken und Ziele kann der zu leistende Aufwand nicht realistisch geschätzt werden, die daraufhin allokierten Ressourcen, bereitgestellten monetären Mittel und die geplante Projektlaufzeit reichen für eine erfolgreiche Projektumsetzung nicht aus. Die initiale Verständnisbildung über Anforderungen und Risiken geschieht in plangetriebenen Vorgehensweisen zu Beginn eines Projekts durch eine umfangreiche Analyse und möglichst vollständige Spezifikation. Das Schreiben vollständiger Spezifikationen ist jedoch unwirtschaftlich, weil soziotechnische Systeme nicht vollständig beschreibbar sind und emergente Anforderungen in erkenntnisgetriebenen Softwareprozessen zu Änderungen führen. In agilen Vorgehensweisen wird das Verständnis durch die gleichen Aktivitäten, jedoch in kurzen Zyklen und ohne vollständige Spezifikation zu Projektbeginn, durch enge Zusammenarbeit zwischen Kunden und Entwicklungsteams hergestellt. Um Projekte erfolgreich planen zu können, müssen die richtigen Anforderungen in angemessenem Detailniveau verstanden und dokumentiert sein. Plangetriebene und agile Vorgehensweisen liefern den organisatorischen Rahmen zur Herstellung eines expliziten und impliziten gemeinsamen Verständnisses. Das Erkennen erfolgskritischer Projektinhalte obliegt der Verantwortung einzelner Rolleninhaber in den Vorgehensweisen – eine strukturierte Herangehensweise, um die Aspekte eines Projektes explizit zu machen, die über Erfolg und Misserfolg eines Projektes entscheiden können, existiert nicht. Um einen Beitrag zum Erfolg von IT-Projekten durch deren realistische Planung zu leisten, wird in dieser Arbeit der Interaction Room vorgestellt: Eine Methode, in der interdisziplinäre Teams pragmatische Modelle über das Verhalten sowie die Struktur eines Informationssystems in moderierten Workshops skizzieren. Sie kennzeichnen Wert-, Aufwands- und Risikotreiber in Modellskizzen, die auf Interaction-Room-Landkarten visualisiert werden. Dabei veranschaulicht die Feature-Landkarte den funktionalen Projekt-umfang. Die Prozesslandkarte veranschaulicht durch das Informationssystem unterstützte Prozesse zur Erfüllung der funktionalen Anforderungen. Die Objektlandkarte veranschaulicht erzeugte und verarbeitete Geschäftsobjekte und die Integrationslandkarte veranschaulicht direkte Schnittstellen des Informationssystems zu benachbarten Systemen sowie ausgetauschte Geschäftsobjekte. Die Kennzeichnung von Wert-, Aufwands- und Risikotreiber geschieht mit Hilfe von getypten Annotationen, die von den Stakeholdern des interdisziplinären Teams auf die Landkarten geheftet, im Anschluss diskutiert und dokumentiert werden. Durch die Annotationstypen lassen sich z. B. Werte für Nutzer, Flexibilitätsanforderungen und Ungewissheit kennzeichnen. Die Erkenntnisse aus Inter-action-Room-Workshops werden in eine pragmatische Struktur für Anforderungsdokumente überführt und können dadurch unmittelbar in Softwareprozessen weiter verwendet werden. Zwischen November 2011 und Februar 2017 wurden 23 Analyse-, Neuentwicklungs-, Weiterentwicklungs- und Migrationsprojekte mit Industriepartnern unterschiedlicher Branchen durchgeführt. Auf dieser Datenbasis wurden unterschiedliche Methodenparameter auf Zusammenhänge untersucht. Erwartungsgemäß bestehen positive Zusammenhänge zwischen Metriken der Projektgröße, zwischen dem Vorschlag zur Verwendung von Annotationstypen und deren tatsächlicher Verwendung, sowie zwischen der Menge verwendeter Annotationstypen und der Anzahl Duplikate. Außerdem besitzen die Inter-action-Room-Annotationen positiven Einfluss auf die Genauigkeit der Aufwandsschätzung. Die Planung von Entwicklungsiterationen kann durch Interaction-Room-Landkarten unterstützt werden, wodurch eine quantitative Verbesserung bei der Identifikation von Arbeitspaketen beobachtet wurde. Die Verbesserung besitzt positiven Einfluss auf die Fortschrittsmessung während einer Iteration und damit auf ihre Erfolgsprognose. Die Intervention kann in ein übliches Vorgehen zur Planung von Entwicklungsiterationen integriert werden, weil sie von den Planenden nicht als störend wahrgenommen wurde

Post-eruptive volcano inflation following major magma drainage: Interplay between models of viscoelastic response influence and models of magma inflow at Bárðarbunga caldera, Iceland, 2015-2018

&amp;lt;p&amp;gt;Unrest at B&amp;amp;#225;r&amp;amp;#240;arbunga after a caldera collapse in 2014-2015 includes elevated seismicity beginning about six months after the eruption ended, including nine Mw&amp;gt;4.5 earthquakes. The earthquakes occurred mostly on the northern and southern parts of a caldera ring fault. Global Navigation Satellite System (GNSS, in particular, Global Positioning System; GPS) and Interferometric Synthetic Aperture Radar (InSAR) geodesy are applied to evaluate the spatial and temporal pattern of ground deformation around B&amp;amp;#225;r&amp;amp;#240;arbunga caldera outside the icecap, in 2015-2018, when deformation rates were relatively steady. The aim is to study the role of viscoelastic relaxation following major magma drainage versus renewed magma inflow as an explanation for the ongoing unrest.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;The largest horizontal velocity is measured at GPS station KISA (3 km from caldera rim), 141 mm/yr in direction N47&amp;lt;sup&amp;gt;o&amp;lt;/sup&amp;gt;E relative to the Eurasian plate in 2015-2018. GPS and InSAR observations show that the velocities decay rapidly outward from the caldera. We correct our observations for Glacial Isostatic Adjustment and plate spreading to extract the deformation related to volcanic activity. After this correction, some GPS sites show subsidence.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;We use a reference Earth model to initially evaluate the contribution of viscoelastic processes to the observed deformation field. We model the deformation within a half-space composed of a 7-km thick elastic layer on top of a viscoelastic layer with a viscosity of 5 x 10&amp;lt;sup&amp;gt;18&amp;lt;/sup&amp;gt; Pa s, considering two co-eruptive contributors to the viscoelastic relaxation: &amp;amp;#8220;non-piston&amp;amp;#8221; magma withdrawal at 10 km depth (modelled as pressure drop in a spherical source) and caldera collapse (modelled as surface unloading). The other model we test is the magma inflow in an elastic half-space. Both the viscoelastic relaxation and magma inflow create horizontal outward movements around the caldera, and uplift at the surface projection of the source center in 2015-2018. Viscoelastic response due to magma withdrawal results in subsidence in the area outside the icecap. Magma inflow creates rapid surface velocity decay as observed.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;We explore further two parameters in the viscoelastic reference model: the viscosity and the &amp;quot;non-piston&amp;quot; magma withdrawal volume. Our comparison between the corrected InSAR velocities and viscoelastic models suggests a viscosity of 2.6&amp;amp;#215;10&amp;lt;sup&amp;gt;18&amp;lt;/sup&amp;gt; Pa s and 0.36 km&amp;lt;sup&amp;gt;3&amp;lt;/sup&amp;gt; of &amp;amp;#8220;non-piston&amp;amp;#8221; magma withdrawal volume, given by the optimal reduced Chi-squared statistic. When the deformation is explained using only magma inflow into a single spherical source (and no viscoelastic response), the optimal model suggests an inflow rate at 1&amp;amp;#215;10&amp;lt;sup&amp;gt;7&amp;lt;/sup&amp;gt; m&amp;lt;sup&amp;gt;3&amp;lt;/sup&amp;gt;/yr at 700 m depth. A magma inflow model with more model parameters is also a possible explanation, including sill inflation at 10 km together with slip on caldera ring faults. Our reference Earth model and the two end-member models suggest that there is a trade-off between the viscoelastic relaxation and the magma inflow, since they produce similar deformation signals outside the icecap. However, to reproduce details of the observed deformation, both processes are required. A viscoelastic-only model cannot fully explain the fast velocity decay away from the caldera, whereas a magma inflow-only model cannot explain the subsidence observed at several locations.&amp;lt;/p&amp;gt; </jats:p

Similarities and differences in the historical records of lava dome-building volcanoes: implications for understanding magmatic processes and eruption forecasting

A key question for volcanic hazard assessment is the extent to which information can be exchanged between volcanoes. This question is particularly pertinent to hazard forecasting for dome-building volcanoes, where effusive activity may persist for years to decades, and may be punctuated by periods of repose, and sudden explosive activity. Here we review historical eruptive activity of fifteen lava dome-building volcanoes over the past two centuries, with the goal of creating a hierarchy of exchangeable (i.e., similar) behaviours. Eruptive behaviour is classified using empirical observations that include patterns of SO2 flux, eruption style, and magma composition. We identify two eruptive regimes: (i) an episodic regime where eruptions are much shorter than intervening periods of repose, and degassing is temporally correlated with lava effusion; and (ii) a persistent regime where eruptions are comparable in length to periods of repose and gas emissions do not correlate with eruption rates. A corollary to these two eruptive regimes is that there are also two different types of repose: (i) inter-eruptive repose separates episodic eruptions, and is characterised by negligible gas emissions and (ii) intra-eruptive repose is observed in persistently active volcanoes, and is characterised by continuous gas emissions. We suggest that these different patterns of can be used to infer vertical connectivity within mush-dominated magmatic systems. We also note that our recognition of two different types of repose raises questions about traditional definitions of historical volcanism as a point process. This is important, because the ontology of eruptive activity (that is, the definition of volcanic activity in time) influences both analysis of volcanic data and, by extension, interpretations of magmatic processes. Our analysis suggests that one identifying exchangeable traits or behaviours provides a starting point for developing robust ontologies of volcanic activity. Moreover, by linking eruptive regimes to conceptual models of magmatic processes, we illustrate a path towards developing a conceptual framework not only for comparing data between different volcanoes but also for improving forecasts of eruptive activity

Unexpected large eruptions from buoyant magma bodies within viscoelastic crust

Large volume effusive eruptions with relatively minor observed precursory signals are at odds with widely used models to interpret volcano deformation. Here we propose a new modelling framework that resolves this discrepancy by accounting for magma buoyancy, viscoelastic crustal properties, and sustained magma channels. At low magma accumulation rates, the stability of deep magma bodies is governed by the magma-host rock density contrast and the magma body thickness. During eruptions, inelastic processes including magma mush erosion and thermal effects, can form a sustained channel that supports magma flow, driven by the pressure difference between the magma body and surface vents. At failure onset, it may be difficult to forecast the final eruption volume; pressure in a magma body may drop well below the lithostatic load, create under-pressure and initiate a caldera collapse, despite only modest precursors

Global link between deformation and volcanic eruption quantified by satellite imagery

A key challenge for volcanological science and hazard management is that few of the world’s volcanoes are effectively monitored. Satellite imagery covers volcanoes globally throughout their eruptive cycles, independent of ground-based monitoring, providing a multidecadal archive suitable for probabilistic analysis linking deformation with eruption. Here we show that, of the 198 volcanoes systematically observed for the past 18 years, 54 deformed, of which 25 also erupted. For assessing eruption potential, this high proportion of deforming volcanoes that also erupted (46%), together with the proportion of non-deforming volcanoes that did not erupt (94%), jointly represent indicators with ‘strong’ evidential worth. Using a larger catalogue of 540 volcanoes observed for 3 years, we demonstrate how this eruption–deformation relationship is influenced by tectonic, petrological and volcanic factors. Satellite technology is rapidly evolving and routine monitoring of the deformation status of all volcanoes from space is anticipated, meaning probabilistic approaches will increasingly inform hazard decisions and strategic development