Figure 1. DGGS geologist Janet Schaefer inspects layers of volcanic ash (tephra) erupted from Makushin volcano, near Dutch Harbor/Unalaska.
Photo by USGS geologist Christina Neal, August 9, 2013.
In 2014 AVO began developing Phase I of the Alaska Tephra Database project. The tephra database works seamlessly with other AVO database modules as part of the larger Geologic Database of
Information on Alaska Volcanoes (GeoDIVA). The end result will be the first-ever comprehensive database of Alaska tephra (volcanic ash). This database will house all pertinent information
on Alaska tephras necessary for sample processing, archiving, and scientific research. Developing correlations of tephra records across Alaska and the northern hemisphere requires an
understanding of the age, chemistry, and character of tephra deposits. Tephra studies are a key component in understanding the magnitude and frequency of volcanic eruptions and help
improve volcanic ashfall hazard assessments (fig. 1). In addition, tephrostratigraphy is an integral part of linking marine, lacustrine, and terrestrial records to aid research in paleoclimate
studies and archaeology (fig. 2).
Photo of 1 meter of lake core extracted from Mother Goose Lake near Chiginagak volcano. More than 50 tephras are preserved in cores like this from Mother Goose Lake,
recording more than 3,000 years of volcanic activity at Chiginagak volcano and nearby volcanoes on the Alaska Peninsula. Photo by Chris Kassel, former graduate student at Northern Arizona University.
Currently, Alaska tephra chemical, stratigraphic, and age data are dispersed in hundreds of publications and unpublished lab results, making efficient querying of data for specific research purposes impossible.
Creating and populating a single, comprehensive tephra database and developing web portals for easy access will alleviate this difficulty, and open up Alaska tephra data to geoscientists everywhere.
Phase I accomplishments include: (1) loading of test datasets; (2) ability to query glass geochemical data by sample ID, source volcano, and glass chemistry and (3) computation of glass chemistry
similarity coefficients for multiple tephra samples. Query and computational features are still in development and available for internal AVO use only; we hope to make this feature available to the public soon.
Phase II, to begin in 2015, will consist of: (1) sorting tephra datasets in preparation for geochemical and sample metadata upload; (2) developing a streamlined upload process for new data; (3) developing a database
schema to store age data; and (4) developing a database schema to hold sample fraction information.
December 2016 update:
Over 600 published and unpublished resources have been reviewed for tephra information and the Alaska Tephra Database now contains over 2,600 Pleistocene-Present tephra glass analyses and their sample metadata. Similarity coefficients can be calculated with queried sets of data. Before going public, staff is working to clean up data entries and provide the capability to search by tephra name, age, and chemistry.
Phase III project goals include expanding the database to store sample preparation details and individual grain-point and mineral analyses, and creating a laboratory database interface for post-field sample preparation.
INTERESTED IN SUBMITTING YOUR TEPHRA DATA?
If you are interested in submitting your published data for inclusion in the Alaska Tephra Database, please contact AVO's database manager, Cheryl Cameron
, Alaska Division of Geological & Geophysical Surveys, Geologist/Database Manager
, Alaska Division of Geological & Geophysical Surveys, Geologist/Volcanology Section Chief
, Alaska Division of Geological & Geophysical Surveys, Analyst/Programmer
, U.S. Geological Survey, Geologist/Alaska Tephra Lab Manager
Katherine Mulliken, Alaska Division of Geological & Geophysical Surveys, Geologist/Tephra Data Loading