When analysing volcanic seismicity and volcanic events, it is often interesting to focus on tremor, which is a signal of long duration. This is because not much is known about tremor. Unlike earthquakes, sources of tremor are difficult to locate due to them not having any clear onsets in the seismic signal. Different location methods can be used to attempt to locate tremor sources, one of which incorporates correlation of seismic signals between two different recording stations. This method is sensitive to the frequency content in the signal, and will not operate correctly if the signal consists of non-tremor signals, e.g. earthquakes. Earthquakes generally contain higher frequencies than tremor, and if these are present in the signals being correlated, this will affect the location method negatively. Therefore, it is desirable to try to detect these events containing other frequencies, to be able to remove them from the data and improve the location method. Constructing this method is the objective of the study, and is done using the programming language Matlab. The method uses correlation between the amplitude spectra of short adjacent time intervals of the bigger time series, in an attempt to detect when the spectral signature of the time series radically changes. An outlier is deemed to exist when the correlation coefficient from the comparison falls beneath a pragmatically chosen multiple of standard deviation from the mean of coefficient values. The objective of the study has been achieved, by constructing a method using correlation between time intervals to detect sudden fluctuations in the spectral shape of the time series. The method does seem promising, however, the accuracy of the method now needs to be rigorously tested. Time has not allowed for this to be done in this study, and is left for future research. / När man analyserar vulkaniska händelser och seismik är det ofta intressant att fokusera på tremor, vilket är långvariga händelser. Detta är p.g.a. att inte mycket är känt om des-sa. Till skillnad från jordbävningar, så är orsaken till tremor svår att lokalisera eftersom dom inte har en tydlig början i den seismiska signalen. Olika lokaliseringsmetoder kan användas för att försöka lokalisera dessa orsaker, varav en är en metod som använder sig av korrelationen mellan den seismiska signalen för två olika mätstationer. Denna metod är känslig för innehållet av frekvens i signalen som används i jämförelsen, och kommer inte fungera lika bra om signalerna innehåller annat än endast tremor, t.ex. jordbävningar. Jordbävningar innehåller generellt högre frekvenser än tremor, och ifall dessa är närvarande i signalerna som används i jämförelsen kommer detta påverka metoden negativt. Därför är det önskvärt att försöka hitta dessa händelser som ger upphov till andra frekvenser, för att sedan kunna avlägsna dessa och förbättra lokaliseringsmetoden. Målet med detta projekt är därmed att konstruera denna metod, och detta genomförs i programmeringspråket Matlab. Metoden använder sig av korrelation mellan amplitudspektrum av korta närliggande tidsintervall från den större tidsserien, för att försöka detektera när frekvensinnehållet i signalen ändras radikalt. Ett interval anses vara en avvikelse närkorrelationskoefficienten från jämförelsen faller under en pragmatiskt vald multipel av standardavvikelsen av medelvärdet av korrelationskoefficienterna.Målet med projektet har uppfyllts, genom att konstruera en metod som använderkorrelation mellan tidsintervall för att detektera plötsliga fluktuationer av dom frekvensersignalen innehåller. Metoden verkar lovande, men noggrannheten av den behöver nu testas rigoröst. Tyvärr kunde inte detta utföras inom tidsgränserna av detta projekt, och får lämnas som framtida forskning.

Mt. Spurr is a volcano in proximity to Anchorage, Alaska and major airline routes making an eruption or episode of unrest potentially hazardous. Between 2004 and 2006, Mt. Spurr underwent such an episode of unrest involving increased seismic activity, CO2 emissions, ice melting, and debris flows, which was likely forecasted by the increased seismicity of Oct 2002. The timeline of events provide data to construct a model analyzing the thermal energy release and constraining subsurface magmatic and hydrothermal processes during the period of unrest. The results show that the ice cauldron formation and the increase of meltwater temperature could not have been caused by the observed CO2 release alone and suggest that enhanced hydrothermal heat transfer related to increased CO2 output could provide the thermal power necessary to drive the melting event. Scaling hydrothermal convection in terms of its Rayleigh number and using boundary layer analysis suggests that the mean permeability of the volcanic edifice prior to the unrest event was ~10-14 m2. CO2 release, most likely related to mechanical fracturing of the edifice by over-pressurized fluids at depth and signaled by increased seismicity likely enhanced the hydrothermal Rayleigh number and heat output by a combination of heating and increased permeability. / Master of Science

Graduation date: 2002 / Best scan available for black and white figures.

Spektralradiometermessungen (spektrale optische Dicke und Himmelshelligkeitsfunktion) unter Hochgebirgsbedingungen (Zugspitze, 2965 m) wurden zur Bestimmung der klirnarelevanten Aerosolparameter des stratosphärischen Vulkanaerosols (speziell des Pinatubo) verwendet. Die erhaltenen klirnarelevanten Aerosolparameter aus den Meßkampagnen werden mit Angaben der Aerosolklimatologien verglichen und zur Abschätzung des kurzwelligen Strahlungsforcings durch das Pinatubo-Aerosol verwendet. / Spectral radiometer measurements (spectral optical thickness and sky brightness function) under high mountain conditions (Zugspitze, 2965 m) have been used for the determination of climate-relevant aerosol parameters of the stratospheric volcanic aerosol (columnar size distribution, refractive index, phase function and asymmetry parameter - especially of the aerosol of the Pinatubo volcano eruption in 1991). The climate-relevant aerosol parameters of the measurement campaigns and their temporal change have been compared with data of the aerosol climatologies and have been used for the estimation of the short wave radiative forcing of the Pinatubo event.

Satellite measurements of volcano deformation have the potential to illuminate a wide range of volcanic processes and have provided us with the first opportunity to investigate volcano deformation as an arc-scale process. This thesis presents the results of an Interferometric Synthetic Aperture Radar (InSAR) survey of the Central American Volcanic Arc between 2007 and 2010. My measurements confirm a statistically significant absence of magmatic deformation in Central America relative to other well-studied volcanic arcs. I estimate a minimum detection threshold for deformation at 20 of the arc’s 26 active volcanoes using time series analysis of interferometric phase. I find that the majority (∼80%) of literature measurements of volcano deformation made at other arcs would have been possible with the average magnitude of noise in Central American volcanoes. The absence of measurable magmatic deformation in Central America may therefore be due to factors that limit the geodetic expression of magma movement, including the deep pooling of basalts and high parental melt volatile content. The quantification of measurement uncertainty also allows me to use the lack of deformation at specific erupting volcanoes to make order of magnitude estimations of the minimum depth for magma storage that would not result in measurable deformation. I present measurements and interpretation of non-magmatic deformation associated with edifice development at two Central American volcanoes: Arenal, Costa Rica and Santiaguito, Guatemala. At Arenal, I measure apparently steady slip (∼7 cm/yr) on the volcano’s western flanks, which I attribute to gravity-driven slip on the boundary between lavas emplaced over the past 50 years and older tephras and paleosols. At Santiaguito, I demonstrate the measurement of large-scale (∼10-200 m) topographic change from a small set of large baseline interferograms. Measurements of post-2000 lava fields allow me to estimate extrusion rate, map changes to flow morphology and make simultaneous measurements of lava flow thickness and subsidence rate.

第18回名古屋大学年代測定総合研究センターシンポジウム平成17(2005)年度報告 Proceedings of the 18th symposiumon on Chronological Studies at the Nagoya University Center for Chronological Research in 2005 日時:平成18 (2006)年1月17日(火)､18日(水) 会場:名古屋大学シンポジオン Date:Januaryl7th and 18th, 2006 Venue:Nagoya Uhiversity Symposion Hall

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Natural disasters and rapid environmental changes have resulted in a continuum of responses by human societies throughout history. A model is proposed that incorporates cultural and environmental aspects of human response to natural disasters. The 11th century eruption of Sunset Crater volcano in northern Arizona is used as a case study in which the archaeological record and dendrochronological and geomorphological evidence are combined to characterize the nature of the human response. The model predicts that the population at Sunset Crater would have been pressured to move, or to move and make cultural or technological adaptations following the eruption. The model has utility in diverse conditions and can be used to interpret archaeological remains and facilitate modern disaster response.

This study assesses the geological constraints on fluid flow within the main crater of Whakaari volcano (White Island) which is located in the Bay of Plenty, New Zealand. A review of the volcanological and morphological history, field mapping, and permeability experiments were used to propose a model for single-state (gas or liquid water) fluid flow in the volcano. Three structural scales were of most importance: (a) the elongate main crater (1.2 km by 0.5 km); which contains (b) three subcraters (~300-500 m in diameter); and (c) >14 historic eruption craters and crater complexes (30-300 m in diameter). A large (2.1x10⁸ m³) sector collapse formed the basic morphology and structure of the amphitheatre-like main crater ≤3.4 ka. Hot fluids are released from magma at ~1–2 km depth and circulated within a conduit-hosted volcano-hydrothermal system. The collapse event was likely to have removed low permeability cone lavas, significantly increasing meteoric water collection and lateral seawater infiltration within high permeability main crater fill above the magma conduit. It is proposed that this caused a susceptibility to ‘wet’ (i.e. phreatic and phreatomagmatic) eruptions which possibly formed three prehistoric subcraters and has been demonstrated in the last ~200 years of available historic record. The permeability of the remaining in-situ cone lavas is controlled by micro- (<1 mm) and macro- (>1 mm) cracks but despite these cracks, the cone lavas’ permeability is still sufficiently low to focus rising magmatic fluid flow through main crater fill. Low-to-high permeability lithified tuffs are inferred to fill the main crater at depth. Low permeability fine ash tuffs generally restrict vertical fluid flow put permit it when vertical trains of vesicles are present. Atmospheric steam and gas pluming is accommodated by a permeable zone of repeated and overlapping historic eruption crater-related discontinuities that extend to >250 m depth through highly permeable unlithified main crater fill in the west. It is likely to be this material into which the seawater infiltrates from the east. Throughout the main crater, fluid flow is focussed at subcrater margins due to steeply-dipping discontinuities between low permeability lava and low-to-high permeability crater fill deposits. The variable permeabilities of crater fill deposits are due to age-related factors of hydrothermal alteration, reworking/sorting, consolidation, and pore mineralisation. At shallow levels (<100 m depth), vertical fluid flow is diverted to historic eruption crater margins by very low permeability clay (reworked and altered tephra). High permeability coarse ash tuffs, Fe-rich lapilli tuffs, and surficial solfatara deposits do not appear to have much effect on the overall fluid flow system. The results of this study show that, within active volcanic craters, the spatial distributions of variably permeable lithologies are often related to discontinuous cratering structures. Together, these are significant geological constraints on fluid flow. Morphological changes to crater structure can directly impact the groundwater regime above the magma conduit and may strongly influence the occurrence of wet versus dry eruptions. This process is possibly a significant control on eruptive behaviour at volcanoes with similar fluid flow systems worldwide.

The study of magmatic processes and their location in the crustal profile is fundamental for the understanding of the volcanic systems and their associated hazards. Changes and continuities in magma storage zones, fractional crystallization and crustal contamination are studied over a time span of 300 ka in Puyehue Volcano in the Southern Volcanic Zone, Chile. Using thermobarometric models outlined in Putirka (2008), bulk assimilationand fractional crystallization modelling this study show that: a) fractional crystallization of plagioclase and clinopyroxene in Puyehue Volcano occurs in the upper 20 km of the crust with plagioclase preceding clinopyroxene in the crystallization sequence, b) fractional crystallization of basaltic andesites is dominated by plagioclase with a break in th e geochemical trend at around 55 wt% SiO2caused by an increased share of pyroxene fractionation and the onset of significant magnetite fractionation, c) both old and young Puyehue volcanics are contaminated by a gabbroic lithology of the lower crust as suggested previously by Jicha et al. (2007) and d) the Anticura Group lavas and a single Puyehue Volcano sample reflect magma-metasediment interaction with likely in the middle to upper crust. / El estudio de los procesos magmáticos y su ubicación en el perfil de la corteza terrestre es fundamental para la comprensión de los sistemas volcánicos y sus riesgos asociados. Cambios y continuidades en las zonas de almacenamiento de magma, cristalización fraccionada y contaminación cortical correspondientes a un lapso de 300 ka se estudiaronen Volcán Puyehue en la Zona Volcánica Sur, Chile. Utilizando modelos termobarométricos descritos en Putirka (2008) más un modelamiento de la asimilación y cristalización fraccionada este estudio muestra que: a) la cristalización fraccionada de plagioclasa y clinopiroxeno en el Volcán Puyehue se produce en los 20 Km superiores de la corteza y que la plagioclasa precede al clinopiroxeno en la secuencia de cristalización, b) la cristalización fraccionada de andesitas basálticas está dominada por plagioclasa con un quiebre en la tendencias geoquímicas en torno al 55 wt%SiO2causado por un aumento relativo delfraccionamiento piroxeno y ael comienzo de un fraccionamiento significativo de magnetita, c) las rocas volcánicas del Volcán Puyehue, tanto lasantiguas como las recientes, están contaminadas por una litología de gabro de la corteza inferior como se ha sugeridoanteriormente por Jicha et al. (2007) y d) las lavas del Grupo Anticura además de una sola muestra Volcán Puyehue evidencian interacción entre magma y metasedimentos que probablemente ocurrió en la corteza media o superior / Studiet av magmatiska processer och deras placering i jordskorpans profil är väsenlig för förståelsen av den vulkaniska system och dithörande risker. I denna studie granskas förändringar och kontinuiteter i lagringszoner för magma, fraktionerad kristallisation och jordskorpsföroreningar över en tidsperiod på 3 00 ka i Puyehue vulkan i den Södra Vulkaniska Zonen, Chile. Till denna ändamål användes termobarometriska modeller beskrivna i Putirka (2008) och andra modeller för assimilering och fraktionerad kristallisation som visar att: a) fraktionerad kristallisation av plagioklas och klinopyroxen i Puyehue vulkanen sker i de övre 20 km av jordskorpan och att plagioklas föregår clinopyroxene i kristallisations följden, b) fraktionerad kristallisering av andesitiska basalterförhärskas av plagioklas samt att den geokemiska utvecklingen förändras omkring 55 wt% SiO2på grund av en ökad fraktioneringsandel av pyroxen plus uppkomsten av betydande magnetit fraktionering, c) både gamla och unga Puyehue vulkaniter är förorenade av ett gabbroisk litologi från den undre kontinentalskorpanså som detföreslagits tidigare av Jicha et al. (2007) och d) Anticura Group lavornasamt ett enda Puyehue-prov reflekterar magma-metasediment interaktion som sannolikt sker i mitten eller övre delenav kontinentalskorpan.