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Chapman Conferences ABSTRACTS listed by name of presenter Allen, Richard M. numerical modeling we test whether motion of the southern flank of Kilauea volcano can be understood as a ‘secular’ Comparative plumeology: Contrasting seismic (continuous) gravity collapse that is modulated by constraints on mantle plumes intrusions or earthquake events. For comparison of our Allen, Richard M.1; Cheng, Cheng1; Porritt, Robert1 model results we use geodetic velocities based on data from a time period that shows little effect of episodic magmatic and 1. Earth and Planetary Science, Univ California Berkeley, tectonic events (2000-2003), which show the seaward motion Berkeley, CA, USA of the south flank and subsidence at Kilauea summit. We Ever since the whole mantle plume hypothesis was first find that gravity-only driven models can reproduce the proposed there has been a vigorous debate over the origins geodetic surface velocities if we incorporate a regional of volcanic hotspots. Many hoped that the ability of seismic decollement fault, and a shallow, low viscosity magma tomography to image 3D velocity structure, when applied to chamber. A rift above the magma chamber was necessary to hotspot locations, would resolve this question. This has not add to the model geometry in order to allow reaching steady- been the case. Today we have global tomography models that state velocities, for which we estimate the magma mush are interpreted to show mantle plumes and others that do viscosity to ~ 1 x 1019 Pa.s, with about half of the subsidence not. Temporary seismic deployments in hotspot locations amplitude at Kilauea summit to be explained by flank have been designed specifically to provide higher resolution motion only. images of mantle structure to constrain the origins of hotspots. While they usually show low velocities in the upper Amelung, Falk mantle beneath hotspots, they usually lack the simple Top-down inflation and deflation at the summit of vertical cylindrical structure predicted by simple geodynamic Kilauea volcano, Hawaii, observed with InSAR models. This again leads to multiple varied interpretations. Here we take a comparative approach in an effort to Amelung, Falk1; Baker, Scott1 understand the real differences, or similarities, in mantle 1. Marine Geology and Geophysics, University of Miami - structure beneath hotspots. We use seismic data from dense RSMAS, Miami, FL, USA regional seismic deployments above Hawaii, Yellowstone and Iceland and compare the mantle structures resolved beneath We use interferometric synthetic aperture radar (InSAR) each. We account for the variable station distribution and to study the inflation-deflation sequence of the summit identify where differences in mantle velocity structure really caldera at Kilauea volcano during 2000-2008, which led to exist. We then compare the relative seismic structures to the 2007 intrusion in the east rift zone and a summit other constraints on mantle processes beneath each hotspot eruption that started in 2008. The data set consists of small in an effort to identify whether a single mantle process can baseline subset (SBAS) time-series generated from 270 explain all three hotspots. acquisitions on 3 separate beam modes from the Radarsat-1 satellite. We identify 12 time periods with distinct patterns Amelung, Falk of displacement that we attribute until 2004 to secular tectonic-driven deformation and from 2004-2008 to four Numerical modeling of flank motion at Kilauea different sources in the summit area. The shallow magmatic Volcano, Hawai’i system consists of a spherical reservoir at 1.9 km depth to Plattner, Christina1; Baker, Scott2; Amelung, Falk2; Govers, the northeast of Halema’uma’u (source 1) and 3 vertically Rob3; Poland, Mike4 stacked sills at greater depths in the southern caldera area (sources 2 at the southern edge of the caldera at 2.9 km 1. Geomatics Engineering, Florida Atlantic University, Port depth, source 3 to the south-southeast of the caldera at 3.6 St. Lucie, FL, USA km depth, and source 4 south of the caldera at 3.6 km 2. Marine Geology and Geophysics, University of Miami, depth). The sequence for filling and emptying these shallow RSMAS, Miami, FL, USA summit reservoirs reveal a top-down process, with the 3. Geoscienes, Utrecht University, Utrecht, Netherlands shallow sources being the first to inflate as well as the first 4. Hawaiian Volcano Observatory, US Geological Survey, to deflate. Inflation of source 3 is coincident with seismic Volcano NP, HI, USA swarm activity in the upper east rift zone in February 2006 Multiple causes have been suggested for the seaward and May 2007. Source 4 is elongated toward the southwest motion of Kilauea’s south flank, including forceful dike rift zone and also shows elevated seismicity that extends intrusions into the rift zone, and magmatic toward the southwest rift. The activation of the deeper sills overpressurization or gravitational spreading of a deep (sources 3 and 4) correlates with the time-varying strength of partial-melt carrying olivine cumulate. The continuity of the the upper east rift zone. When the rift zone is strong (such flank motion during inflation and deflation of Kilauea as during 2006) magma cannot break into the rift. Dike summit suggest that gravity plays a substantial role. Using intrusions fail and the deeper sills inflate. When the rift 17 zone is weak (such as in 2007 following several M4+ Badger, Nickles B. earthquakes), the magma can pass through this zone to intrude as dikes further down the rift. Inflation of the Infrasonic jetting from the Kamoamoa fissure deeper sills may serve as a proxy for the degree of eruption, Kilauea Hawaii, 5–9 March 2011 pressurization in Kilauea’s shallow system. We also will Badger, Nickles B.1; Garces, Milton A.1; Perttu, Anna B.1; discuss 2008-2011 InSAR data and their implications for Poland, Michael2; Thelen, Weston2 magma storage within Kilauea’s rift zone. 1. Infrasound Laboratory, HIGP, University of Hawaii at Anderson, Kyle R. Manoa, Kailua Kona, HI, USA 2. USGS Hawaiian Volcano Observatory, Hawaii Volcanoes The Shallow Magmatic System at Kilauea Volcano: National Park, HI, USA Insights from Episodic Ground Tilt Following months of elevated seismic tremor and Anderson, Kyle R.1; Poland, Michael1; Miklius, Asta1 inflation at Kilauea Volcano, Pu`u `O`o and 1. Hawaiian Volcano Observatory, Hawaii National Park, HI, Hale`mau`mau craters underwent rapid deflation USA associated with the 5 March opening of the Kamoamoa eruptive fissure. This eruption sequence was captured in its Episodic ground tilt has been observed at the summit of entirety by a four-element infrasound array located ~12.5 km Kilauea Volcano for more than a decade. These deflationary NW of the fissure and orthogonal to its strike. Acoustic and inflationary tilt cycles, termed “DI” events, typically last signals from this array provided real-time, high-fidelity 1-4 days and are often followed after a delay of 30-90 spatial and temporal constraints on volcanic jetting minutes by similar behavior at the Pu`u `O`o eruptive vent, associated with the fissure eruption. Fountaining along the 20 km from the summit. While the events are most likely ~2.3 km fissure varied substantially both spatially and in related to cycles of pressurization and depressurization in intensity. We carry out array processing of infrasonic jetting the magmatic plumbing system, the cause of this behavior is signatures in the 0.5 – 10 Hz frequency band, which appear unclear. To date, more than 300 events have been recorded. to be associated with fountaining activity. Infrasonic To gain insight into the DI source mechanism, its evolution observations over the course of the eruptive episode suggest with time, and its relation to other volcanic processes, we that the fissure progressed away from Pu`u `O`o and carry out an investigation using tilt data collected since toward Napau crater, with at least four clear shifts in jetting 1999, inverting the data using a kinematic model of a activity between opposite ends of the fissure. We also observe magma chamber in a homogenous elastic medium. We multiple spatially-separated source regions with distinct invert to estimate, among other parameters, the location of infrasonic signatures, suggesting different yet synchronous the source and its magnitude (volume times pressure acoustic source processes. In addition we note a reduction in change). Although simple kinematic models of this type mean infrasonic frequency over time, which may be related cannot generally be used to independently constrain both to changes in the volume flux and fissure geometry as the the volume of the source and its pressure change, the eruption evolved. summit lava level (when present) has closely tracked tilt events and suggests that both respond to variations in Bagdassarov, Nikolai S. shallow magma reservoir pressure. Variations in lake level can be used to help constrain changes in magma reservoir Hindered crystal settling in magma chambers pressure associated with tilt events, and therefore to place Bagdassarov, Nikolai S.1 bounds on absolute volume of the reservoir. Future work 1. Institut for Geowissenschaften, J W Goethe Univ will involve development of a physics-based model of DI Frankfurt, Frankfurt Main, Germany events which will also allow us to use additional datasets (e.g., seismic, gravity, gas emissions, etc.) to constrain Hindered settling of crystals in magmatic systems inversions, and will help us to explain the time evolution of containing about 40 or more vol.% of crystals is a widespread the tilt signal during events and the relationship to tilt at phenomenon. It is called hindered settling for a reason — the Pu`u `O`o. added number of crystals in an enclosed area creates a slower-moving sedimentation mixture than would normally be expected from Stokes sedimentation. Hindered settling of magmatic crystals play a decisive role in time scaling of gravitational cumulates formation in crystallizing magma chambers, sills, or lava lakes of typically mafic to ultramafic composition.
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