One of the most deadly products of a volcanic eruption, and the focus of this research, is pyroclastic density currents. These superheated, ground-hugging flows of gas and rock can travel tens of miles away from the volcano at speeds up to 450 miles per hour, overwhelming nearby communities. It is important to understand these events and the relationships with their deposits to provide hazard assessments and evacuation plans in order to reduce the risk of loss of life. This must be accomplished without endangering the lives of scientists.
This multi-spatial scale investigation links satellite-based interpretations of large block and ash flow deposit morphologies to field observations, allowing the rapid and safe identification of features that link directly to eruption processes. The research involves mapping block and ash flow deposits on Shiveluch (Figure 1), and pyroclastic flow deposits on Mount St. Helens (Figure 2), for a qualitative and quantitative comparison of the different deposit types. A history of the current eruptive episode at Shiveluch provides insight into a long-lived dome-forming eruption, by investigating the dome collapse events and the resulting deposits. This is done by analyzing the morphologies, distributions, and temperatures of the events over time using the different Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite data products. An in-depth morphological study is giving insight into the late-stage deposition of block and ash flows at Shiveluch volcano, using high-resolution data (< 1m/pixel) QuickBird-02 and WorldView-02 data.
Figure 1. Investigating block and ash flow deposits on Shiveluch volcano, Kamchatka. Photo by Janine Krippner.
Figure 2. Comparative field study on the Mount St. Helens pumice plain that was deposited during the May 18, 1980 eruption. Photo by Janine Krippner.
Shiveluch volcano is currently undergoing active dome growth and collapse with occasional larger eruptions producing column collapse. This activity produces block and ash flow deposits that vary in morphology, size, shape, and block content. The active dome and more recent deposits are being investigated using the ASTER thermal infrared, shortwave infrared, visible-near infrared and digital elevation model data (Figure 3). Linking the deposit distribution and runout to the size, location, and temperature profiles of the dome collapse area provides a basis for determining the distribution and extent of future hazards at similar volcanoes. Field work has been conducted on these deposits, which provides critical grown truth for the satellite mapping.
A comparative study is ongoing at Mt. St. Helens volcano as well. These well-studied deposits provide an excellent opportunity to investigate geomorphic and textural similarities between the different deposit types. The database of Mt. St. Helens photographs and field-data collected soon after deposition in 1980 document fresh deposit morphologies, whereas subsequent photographic and satellite data document the erosion. These data provide a fundamental link between fresh deposit morphologies at Shiveluch and the more eroded deposits. The goal is to link these two so that this research may be utilized at other volcanoes around the globe.
Figure 3. ASTER thermal infrared image acquired on 30 December 2010, showing the still warm 28 October 2010 block and ash flow deposit and hotter dome at the summit.
This work will continue to investigate the links between pyroclastic density current deposits and the eruptions that formed them, using a variety of remote sensing datasets and field methods. This will expand to include InSAR and SAR data as a means of investigating deformational change and deposit roughness (block size distribution) using a wider scope of data products.
Funding for this work was provided through NASA Earth and Space Science Fellowship (NNX14AK88H), as well as a Department of Geology Henry Leighton Memorial Graduate Scholarship, a University of Pittsburgh Hewlett International Travel Grant, the University of Pittsburgh International Studies Fund, the Geological Society of America Graduate Student Research Grant, and a USGS Jack Kleinman Grant for Volcano Research. A DigitalGlobe Foundation Imagery Grant provided the high-resolution QuickBird-02 and WorldView-02 data.