A multi-sensor approach to determining volcanic plume heights in the North Pacific
AuthorEkstrand, Angela L.
North Pacific Region
Redoubt Volcano (Alaska)
Augustine Volcano (Alaska)
Okmok, Mount (Alaska)
Cleveland, Mount (Volcano : Alaska)
Kasatochi Volcano (Alaska)
Sarychev Volcano (Russia)
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AbstractDuring a volcanic eruption, accurate height information is necessary to forecast a volcanic plume's trajectory with volcanic ash transport and dispersion (VATD) models. Recent events in the North Pacific (NOPAC) displayed significant discrepancies between different methods of plume height determination. This thesis describes two studies that attempted to resolve this discrepancy, and identify the most accurate method for plume height determination. The first study considered the 2009 eruption of Redoubt Volcano. This study found that the basic satellite temperature method, in which satellite thermal infrared temperatures are compared to temperature-altitude profiles, vastly underestimates volcanic plume height due to decreased optical depth of plumes soon after eruption. This study also found that the Multi-angle Imaging SpectroRadiometer (MISR) produced very accurate plume heights, even for optically thin plumes. The second study investigated the application of MISR data to multiple eruptions in the NOPAC: Augustine Volcano in 2006, Okmok, Cleveland, and Kasatochi volcanoes in 2008, and Redoubt and Sarychev Peak volcanoes in 2009. This study found that MISR data analysis retrieves accurate plume heights regardless of grain size, altitude, or water content. Exceptions include plumes of low optical depth over bright backgrounds. MISR is also capable of identifying ash clouds by aerosol type.
DescriptionThesis (M.S.) University of Alaska Fairbanks, 2012
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Analysis and interpretation of volcano deformation in Alaska: Studies from Okmok and Mt. Veniaminof volcanoesFournier, Thomas J.; Freymueller, Jeffrey; Larsen, Jessica; Cervelli, Peter; Christensen, Douglas; McNutt, Stephen (2008-12)Four studies focus on the deformation at Okmok Volcano, the Alaska Peninsula and Mt. Veniaminof. The main focus of the thesis is the volcano deformation at Okmok Volcano and Mt. Veniaminof, but also includes an investigation of the tectonic related compression of the Alaska Peninsula. The complete data set of GPS observations at Okmok Volcano are investigated with the Unscented Kalman Filter time series analysis method. The technique is shown to be useful for inverting geodetic data for time dependent non-linear model parameters. The GPS record at Okmok from 2000 to mid 2007 shows distinct inflation pulses which have several months duration. The inflation is interpreted as magma accumulation in a shallow reservoir under the caldera center and approximately 2.5km below sea level. The location determined for the magma reservoir agrees with estimates determined by other geodetic techniques. Smaller deflation signals in the Okmok record appear following the inflation pulses. A degassing model is proposed to explain the deflation. Petrologic observations from lava erupted in 1997 provide an estimate for the volatile content of the magma. The solution model VolatileCalc is used to determine the amount of volatiles in the gas phase. Degassing can explain the deflation, but only under certain circumstances. The magma chamber must have a radius between ~1and 2km and the intruding magma must have less than approximately 500ppm CO2. At Mt. Veniaminof the deformation signal is dominated by compression caused by the convergence of the Pacific and North American Plates. A subduction model is created to account for the site velocities. A network of GPS benchmarks along the Alaska Peninsula is used to infer the amount of coupling along the mega-thrust. A transition from high to low coupling near the Shumagin Islands has important implications for the seismogenic potential of this section of the fault. The Shumagin segment likely ruptures in more frequent smaller magnitude quakes. The tectonic study provides a useful backdrop to examine the volcano deformation at Mt. Veniaminof. After being corrected for tectonic motion the sites velocities indicate inflation at the volcano. The deformation is interpreted as pressurization occurring beneath the volcano associated with eruptive activity in 2005.
Satellite thermal remote sensing of the volcanoes of Alaska and Kamchatka during 1994-1996, and the 1994 eruption of Kliuchevskoi volcanoWyatt, W. Christopher (2001-05)The Advanced Very High Resolution Radiometers on the NOAA polar orbiting satellites were used to routinely observe the volcanoes of Alaska and Kamchatka from May 1994 to July 1996, as part of the monitoring effort of the Alaska Volcano Observatory. The largest eruption observed during this period occurred at Kliuchevskoi Volcano between September 8 and October 2, 1994. Radiative temperature measurements made during this eruption were used to develop quantitative methods for analyzing volcanic thermal anomalies. Several parameters, including maximum temperature, anomalous pixels, and total volcanic signal (TVS), were compared to viewing angle and date. A new quantity, TVS7, may most effectively monitor the temporal evolution of the eruption using thermal data. By combining several observations of the thermal state of the volcano, the general nature of the volcanic activity can be described. These observations may indicate an elevation in temperature twelve to 24 hours before an ash-producing event.
Using GPS as a reference frame for SAR images applied to a post eruptive period for Okmok Volcano, Aleutian Islands, AlaskaMiller, Summer A. (2012)While high spatial coverage makes InSAR a popular tool to study active volcanoes its use can possess challenges for certain environments. Volcanoes along Alaska's Aleutian chain are difficult targets for InSAR as their seasonal snow cover causes decorrelation close to the volcanic caldera, their exposed location in the North Pacific renders them prone to severe atmospheric phase artifacts, and their location on small islands prevents the selection of suitable reference points necessary for deformation analysis. Existing GPS networks define a known reference frame in which SAR is better understood. Okmok volcano is one of the most active volcanoes in the Aleutian Island Chain and shows significant non-linear deformation behavior as it progresses through its eruption cycles. A stack of L-band imagery acquired by the SAR sensor PALSAR on board the JAXA Advanced Land Observing Satellite produced a post eruption deformation time series between August 2008 and October 2010. This data along with a merged DEM comprised of AirSAR SRTM and Worldview-1 stereo pair data, and GPS data from 3 continuous and 3 post eruption campaign sites was used for this study. In this research, a comparison and combination of InSAR and GPS time-series data will be presented aimed at the following research goals: 1) What is the accuracy and precision of InSAR-derived deformation estimates in such challenging environments; 2) How accurate can the deformation of the InSAR reference point be estimated from a joint analysis of InSAR and GPS deformation signals; 3) How non-linear volcanic deformation can be constrained by the measurements of a local GPS network and support the identification of residual atmospheric signals in InSAR-derived deformation time series. Further research into the combination of GPS and InSAR applied to the nonlinear aspect of volcanic deformation can enhance geodetic modeling of the volcano and associated eruption processes.