GOES weather satellite observations and measurements of the May 18, 1980, Mount St. Helens eruption

Abstract

We demonstrate the use of Geostationary Operational Environmental Satellite (GOES) images of the May 18, 1980, Mount St. Helens volcanic plume in providing details of the dynamics and changing character of this major explosive eruption. Visible and thermal infrared (IR) data from a sequence of images at 30-min intervals from 0850 to 1720 Local Time (LT) give information on dispersal and plume top temperature. Initial visible and IR images at 0850 show the top of a spreading co-ignimbrite-like umbrella plume and an overshooting column emerging from it, both rising off the ground-hugging pyroclastic gravity flow generated by the opening directed blast. The overshooting column had a minimum temperature significantly colder than local ambient atmosphere, indicating substantial undercooling, and a maximum altitude of 31 +2 km at 0920. This large plume system then formed a high-velocity, radially spreading, gravitationally driven current before becoming advected in the wind field at an average downwind velocity of 29 rn/s. Within 30 to 60 min the undercooled plume adjusted to ambient temperatures. After this initial event, the eruption column fluctuated over the next 8 hours between stable Plinian column rise and unstable conditions favoring column collapse, leading to pyroclastic flows and further development of co-ignimbrite ash columns. Over this period of observation, profiles of plume top temperatures derived from IR data versus distance along the downwind axis have distinctive patterns, with steep slopes associated with co-ignimbrite plumes and shallower slopes associated with Plinian plumes. Moreover, reflectance values from visible GOES data change from lower to higher during periods of transition from darker toned Plinian to lighter toned coignimbrite plumes indicating that in this case satellite data resolved changes in eruptive style from plumes with a coarser to a finer dominant particle size. 1986] and radar data [Harris et al., 1981], are available to compare with and to constrain the GOES data. Previous studies of eruption plumes using sequential GOES images, such as Lascar 1986 [Glaze et al., 1989] have been of considerably smaller plumes over much shorter periods and have not provided detailed thermal analysis. Paper number 94JB03137. 0148-0227/95/94JB-03137505.00 0832.7 [Rice, 1981; Moore and Rice, 1984]. Sparks et al. [1986] used photographic and classified satellite observations to show that the vigorously rising plume above the blast flow started at approximately 0837. The plume reached altitudes greater than 30 km and lateral spreading velocities of nearly 60 rn/s as the gas and ash plume intruded into the atmosphere. The first GOES image to capture the MSH eruption plume has a start time of 0845, and contains data acquired over the volcano at about 0850 (see below). As the eruptive style of MSH on May 18, 1980, changed, Plinian and co-ignimbrite-type eruption columns and plumes were produced, as described by observations from the ground [ Criswell, 1987; Carey et al., 1990]. Carey et al. [1990] s...

Characterization of shape and terminal velocity of tephra particles erupted during the 2002 eruption of Etna volcano, Italy

“…The error bar is the corresponding SD that dispersed two-phase air and particle flows in a pipe show inhomogeneous shape in both transverse and streamwise directions. Because irregular particles with the same density and size range can produce quite different velocity profiles, this effect could occur during the sedimentation process in air and could be demonstrated only considering more complex phenomena such as particle interactions or electrostatic phenomena (Holasek and Self 1995;Gilbert and Lane 1994). A first semiquantitative shape characterization of Etna particles was carried out during the 2001 explosive eruption by Taddeucci et al (2002) that found particle shapes covering a wide range from rounded to irregular.…”

Tephra stratigraphy and eruptive volume of the May, 2008, Chaitén eruption, Chile

“…The case of Chaitén volcano seems to be also similar to Mount St. Helens volcano's 1980 activity, which started with a Plinian phase that produced a 19 km high plume (Holasek and Self 1995), erupting a volume of tephra equal to 1.1-1.3 km 3 , followed by extrusion of a lava dome. However, the Mount St. Helens eruption was triggered by a sector collapse and was followed by a decrease in activity characterized by the extrusion of a dacitic dome over several years (Baxter et al 1981).…”

Lava discharge during Etna's January 2011 fire fountain tracked using MSG-SEVIRI

“…These data have the advantage of providing a synoptic view every 15 min, a capability that has meant that they have long been used to track rapidly evolving ash plumes (e.g., Holasek and Self, 1995;Holasek et al 1996), including those associated with fire fountains (e.g., Aloisi et al 2002;Bertrand et al 2003), and to detail shortlived effusive events developing over time scales of less than an hour (e.g., Harris et al 1997a;Harris and Thornber, 1999). We here explore two methods to extract and track time-averaged discharge rates (TADR) for a complex lava flow field resulting from a fountain-fed event at Etna using geostationary satellite (Spinning Enhanced Visible and InfraRed Imager, or SEVIRI) data.…”