Volcanic hotspots of the central and southern Andes as seen from space by ASTER and MODVOLC between the years 2000-2011 (original) (raw)
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Infrared Image Analysis of Volcanic Thermal Features: Lascar Volcano, Chile, 1984-1992
1984 and April 1992, document the evolution of a lava dome within the summit crater. Four of the scenes were acquired at night. In every image, the two short-wavelength infrared bands, 5 and 7, have detected thermal radiation from the volcano. As a consequence of the Planck distribution function, the relative response of these two channels depends on the proportions of very hot (> 600øC) surfaces occupying tiny pixel areas and broader regions at moderate temperatures (< 280øC). Intercomparison of bands 5 and 7 thereby provides a means for interpreting TM thermal anomalies even in the absence of ground observations. Pronounced changes in the configuration and intensity of the L•scar anomaly suggest that the volcano has experienced at least two cycles of lava dome activity since 1984. The first of these progressed through a "cooling" period, possibly reflecting a reduced flux of magmatic volatiles at the surface, and culminated in an explosive eruption on September 16, 1986, which appears to have completely destroyed the inferred lava dome. The TM data indicate that a new dome had been emplaced by November 1987, more than 15 months before it was first discovered by local observers. Lfiscar's style of cyclical effusive and explosive activity is typical of many volcanoes, and the remote sensing techniques presented herein could be applied elsewhere. INTRODUCTION Satellite remote sensing can serve volcanological inquiry in various ways. Preliminary investigations have demonstrated the utility of spaceborne infrared sensors for observing volcanic thermal phenomena such as lava flows and lava lakes [Rothery etal., 1988], fumarole fields [Oppenheimer and Rothery, 1991], and crater lakes [Oppenheimer, 1993]. Detection of new thermal anomalies, or of changes in existing ones, can be of especial value for hazard evaluation. In addition, thermal measurements can illuminate the physical processes that trigger eruptions and influence the behavior of erupted materials. Data from the Landsat Thematic Mapper (TM) enabled Pieri et al. [1990] and Oppenheimer [1991] to infer thermal properties of lava flows.
Journal of Geophysical Research: Solid Earth, 2018
Volcanoes are hazardous to local and global populations, but only a fraction are continuously monitored by ground-based sensors. For example, in Latin America, more than 60% of Holocene volcanoes are unmonitored, meaning long-term multiparameter data sets of volcanic activity are rare and sparse. We use satellite observations of degassing, thermal anomalies, and surface deformation spanning 17 years at 47 of the most active volcanoes in Latin America and compare these data sets to ground-based observations archived by the Global Volcanism Program. This first comparison of multisatellite time series on a regional scale provides information regarding volcanic behavior during, noneruptive, pre-eruptive, syneruptive, and posteruptive periods. For example, at Copahue volcano, deviations from background activity in all three types of satellite measurements were manifested months to years in advance of renewed eruptive activity in 2012. By quantifying the amount of degassing, thermal output, and deformation measured at each of these volcanoes, we test the classification of these volcanoes as open or closed volcanic systems. We find that~28% of the volcanoes do not fall into either classification, and the rest show elements of both, demonstrating a dynamic range of behavior that can change over time. Finally, we recommend how volcano monitoring could be improved through better coordination of available satellite-based capabilities and new instruments. 1. Introduction Volcanic eruptions pose a risk to the life and livelihood of local communities by damaging infrastructure and displacing populations and can have global impacts by disrupting climate, businesses, and air travel (e.g.,
MODIS and ASTER synergy for characterizing thermal volcanic activity
Volcanic activity is diverse in its manifestations and spans wide temporal and spatial scales. Monitoring volcanoes with any single sensor system can only provide a limited perspective on the nature of such activity because of trade-offs between spatial, temporal and spectral resolution. Spaceborne observations of volcanoes are thus optimized by utilizing data from different and complementary remote sensing instruments. This study examines the combined use of the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) for analyzing thermal anomalies from four separate volcanoes: Erta 'Ale (Ethiopia), Kīlauea (Hawai'i), Láscar (Chile) and Kliuchevskoi (Russia). MODIS provides a high temporal resolution (daily) but low spatial resolution (~1 km) dataset and is used to measure volcanic thermal radiance. ASTER provides relatively high spatial resolution (~90 m) image data and is used to define the size of thermal features, albeit at a poorer temporal frequency. Erta 'Ale and Kīlauea have been erupting continuously over the 11-year study period and their thermal emission signatures reveal a persistent baseline on which occasional increases in thermal output, associated with more profuse effusions of lava, are superimposed. Kliuchevskoi also displays occasional peaks in thermal activity due to the eruption of lava however intervening periods are characterized by weak or absent thermal anomalies. Láscar, on the other hand, provides an example of volcanic activity that is difficult for MODIS-type sensors to detect. It is characterized by fumarolic activity that is too low in temperature and too spatially limited to be readily detectable with its coarser instantaneous field of view (i.e., pixel size). However, high resolution data from ASTER can be used to supplement and complement the MODIS dataset. Beyond characterizing the size of thermal anomalies ASTER can also provide constraints on their shape, location and orientation and is capable of detecting relatively subtle thermal anomalies given its high spatial resolution thermal infrared wavebands. These qualities permitted the identification of a thermal precursor to lava flows at Kliuchevskoi. The precursor, which was associated with a rising lava lake, is characterized as an increase in the size and intensity of ASTER-detected thermal anomalies situated in the active crater. Wavelet analysis of the MODIS dataset was also carried out. This revealed the time scales over which radiant output waxed and waned during individual eruptive episodes as well as the repose time between episodes. Such information might be useful in forecasting the likely duration and onset of future eruptions.
Monitoring volcanic thermal anomalies from space: Size matters
Measuring temperatures on volcanoes from space provides important constraints on the transfer of mass and heat to the Earth's surface. Time series of multispectral infrared images, acquired by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) between 2000 and 2009, were inspected to investigate fluctuations in thermal anomalies at both Mount Erebus (Antarctica) and Láscar volcano (Chile). Several thermal metrics were explored: i) maximum pixel temperatures above background, ii) the spatial extent of low, moderate and high temperature anomalies, and iii) the spatial extent of short-wave infrared anomalies. The maximum pixel temperature metric correlated to eruptive events at Láscar volcano yet displayed significant scatter at Erebus. The spatial extent of both temperature and short-wave infrared anomalies correlates well with eruptive activity at both volcanoes. Limited variation in the size of thermal anomalies was observed at Erebus throughout the time series due to the stability of a long-lived lava lake, with the exception of a seasonal expansion in low temperature anomalies associated with localized snow-melt at the peak. This finding has implications for the interpretation of low temperature anomalies at other volcanoes. At least two different types of precursory signals are identified at Láscar: i) a gradual increase and ii) a dip, in the size and intensity of thermal anomalies. These thermal precursors appear to be associated with different eruptive styles. The former precedes a relatively shallow, short lived eruption; the later a prolonged eruptive period. Such thermal precursors could therefore help to constrain not only the timing but also the style and duration of an imminent eruptive episode
Monitoring Colima Volcano, Mexico, using satellite data
Bulletin of Volcanology, 1991
The Colima Volcanic Complex at the western end of the Mexican Volcanic Belt is the most active andesitic volcano in Mexico. Short-wavelength infrared data from the Landsat Thematic Mapper satellite were used to determine the temperature and fractional area of radiant picture elements for two January data acquisitions in 1985 and 1986. The 1986 data showed four 28.5 m by 28.5 m pixels (picture elements) whose hot subpixel components had temperatures ranging from 511-774~ and areas of 1.8-13 m 2. The 1985 data had no radiating areas above background temperatures. Ground observations and measurements in November 1985 and February 1986 reported the presence of hot fumaroles at the summit with temperatures of 135-895 ~ C. This study demonstrates the utility of satellite data for monitoring volcanic activity.