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USGS Alaska Science Center Seminar Series

The USGS Alaska Science Center in Anchorage has a monthly seminar series open to the public. All are welcome to attend! For additional details, to be added to the electronic notification list, or if you would like to conduct a seminar, please contact Yvette Gillies, Outreach Coordinator, at (907)786-7039 or email ygillies@usgs.gov.

January 25, 2012

Remote sensing perspectives on fire disturbance and recovery in high northern ecosystems - Dr. Kirsten Barrett

Increased wildfire disturbance in the Alaskan boreal forest and tundra has the potential to precipitate regional shifts in ecosystem structure and function. Detection and monitoring of remote disturbed areas has been greatly facilitated by remotely sensed data, including active and passive data products from aerial and satellite-based sensors. By combining surface reflectance data with other geospatial datasets such as topography and fire weather data, it is possible to model fire severity at the landscape scale. Based on the area that is likely to have experienced severe burning it is possible to estimate changes in land cover and permafrost degradation in the region as a function of wildfire disturbance over the last decade.

In tundra, remote sensing is often the only regular observation mode of burned areas. While wildfire is less common in tundra than boreal forest, fire activity has increased in recent years. Similar to boreal forests, fire acts as a catalyst for vegetation shifts in tundra that persist over the long term. Permafrost degradation is likely to occur when there is a significant removal of surface organic materials through combustion. Detection and monitoring of burn scars and secondary disturbances such as thermokarsting in burned areas is possible using remotely sensed data supported by field observations. Spectral data are useful for observing shifts in vegetation type, particularly when a long data record is available, while field observations are necessary to determine the cause of shifts in the spectral signature of disturbed areas. Aerial-based RADAR data are useful in detecting thermokarst features such as active layer detachment slides through interferometry. The potential for remote sensing instruments to collect time series data in inaccessible locations is an invaluable resource to scientists and land managers that has made possible the elaboration of ecosystem dynamics of wildfire disturbance in boreal forest and tundra.

February 13, 2012

Investigating Hawaiian fountains: a case study of the 1969 Mauna Ulu eruption of Kilauea - Carolyn Parcheta

Basaltic fissure eruptions are the most common type of eruption in the solar system (e.g., oceanic volcanoes, mid-ocean ridges, and Mars). Diversity in Hawaiian fissure eruptions is of fundamental importance in order to grasp the range of behaviors at frequently active volcanoes like Kilauea, Mauna Loa, and Mount Etna. Most studies focus on high fountains from single vents; there are few accounts of eruptions from fissure sources. Carolyn Parcheta's work spans the gap by looking at the dynamics of weak, sustained, explosive eruptions, principally low-Hawaiian fissure-fountains from the start of the 1969 Mauna Ulu eruption of Kîlauea. The results have raised new issues in classifying less well-documented Hawaiian eruptions, where eruptive style and intensity can only be inferred from the pyroclastic deposits. Deposits may not be what they seem, which can lead to sobering short-comings in the interpretation of eruption dynamics.

Volcanoes like Kîlauea are the sites of large and growing tourism operations (5000 visitors per day to the summit) and there is a public need both for better knowledge of the volcanoes’ behavior and improved forecasting of the likely course of future eruptions. The study of the 1969 Mauna Ulu fissure will also aid in forecasting future eruption hazards at other basaltic systems that erupt less frequently with fissure geometries.

Previous Years' Seminar Series