Alaska Tephra Database

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).

Figure 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.

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. Tephra geochemistry and geochemical correlation tool now available at https://www.avo.alaska.edu/geochem/

1. Cameron, C.E., Mulliken, K.M., Crass, S.W., Schaefer, J.R., and Wallace, K.L., 2019, Alaska Volcano Observatory geochemical database, version 2: Alaska Division of Geological & Geophysical Surveys Digital Data Series 8 v. 2, 22 p., https://www.avo.alaska.edu/geochem/. http://doi.org/10.14509/30058
2. Worden, A.K., Schaefer, J.R., and Mulliken, K.M., 2018, Tephra occurrence in Alaska: a map-based compilation of stratigraphic tephra data: Alaska Division of Geological & Geophysical Surveys Miscellaneous Publication 165, 19 p. http://doi.org/10.14509/30059
3. Mulliken, K.M., Schaefer, J.R., and Cameron, C.E., 2018, Geospatial distribution of tephra fall in Alaska: a geodatabase compilation of published tephra fall occurrences from the Pleistocene to the present: Alaska Division of Geological & Geophysical Surveys Miscellaneous Publication 164, 46 p. http://doi.org/10.14509/29847
4. Wallace, K.L., Hayden, L.A., and Neal, C.A., 2017, Major-element glass compositions of tephra from the circa 3.6 ka eruption of Aniakchak volcano, Alaska Peninsula, Alaska: Alaska Division of Geological & Geophysical Surveys Raw Data File 2017-9, 9 p. http://doi.org/10.14509/29777
5. Mulliken, K.M., Cameron, C.E., Crass, S.W., Schaefer, J.R., and Wallace, K.L., 2017, An update on the Alaska Tephra Database (poster): International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI) 2017 Scientific Assembly, November 14-18, 2017: Alaska Division of Geological & Geophysical Surveys, 1 sheet. http://doi.org/10.14509/29746

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 accomplishments include: (1) uploading published tephra sample metadata and glass EPMA analyses; (2) developing and populating simple age information for search capabilities; (3) construct sample “daughters” and integrate with query capabilities and (4) design and implement an improved search interface for tephra and whole-rock geochemical analyses. Search AVO geochemistry at https://www.avo.alaska.edu/geochem/