Dr. Michael H. Ort

Michael Ort 230px


PhD, University of California


Office: Geology Annex (bldg #13), room 209
Phone: 928-523-9363
E-mail: Michael.Ort@nau.edu
Personal Website

Research interests

My primary research is on volcanoes, including eruption and emplacement processes, petrology, geochemistry, and the interactions of humans with volcanoes. My research into eruption and emplacement processes of pyroclastic flows and surges has focused on large-volume ignimbrites in Argentina and Italy and on maar volcanoes in Arizona, Alaska, and Italy.

The driving question is how do these pyroclastic gravity currents form and move. Because we really only have deposits to work with, my research designs aim to cut through the "filter" of the deposition to get at what the current looked and acted like , at least in the lower part, near the depositional zone. I commonly use careful field work, petrography (optical and electron), and paleomagnetism (especially anisotropy of magnetic susceptibility) as tools. My petrologic interests currently center on the origins of the Hopi Buttes (NE Arizona) monchiquitic and nephelinitic magmas. I have an isotope clean lab and am a co-PI on our new multi-collector ICP mass spectrometer, on which we can do much of the analysis.

I am also currently working on the interaction between humans and the youngest volcanism in the Southwestern USA, concentrating on the ~1050 AD Sunset Crater eruption near Flagstaff and the Little Springs eruption (dated between 1100 and 1200 AD). Both eruptions had profound effects on the people living there then, so I am working with an archaeologist and other geologists to understand how the environment changed.


Research Interests

I am interested in all things volcanic, from igneous petrology and geochemistry to pyroclastic processes (from eruption to emplacement) and magma ascent dynamics.  I use whatever instruments or methods are needed to answer the questions.  These include many different geochemical (e.g. whole rock and mineral geochemistry, isotopes, melt inclusion volatile content) and paleomagnetic (e.g. anisotropy of magnetic susceptibility, magnetic remanence) techniques as well as very detailed stratigraphic work.  In many cases, I can correlate layers with the time of day during an eruption and then use eruption descriptions to help interpret the depositional processes.  In recent years, my work has focused on transport and emplacement from large-volume pyroclastic density currents, explosive water-magma interaction, monogenetic volcanism, and geoarchaeology, with an emphasis on the hazards implications of these processes.


Ort, M.H., Newkirk, T.N., Vilas, J.F., Vazquez, J.A., submitted, Toward the Definition of AMS Facies in the Deposits of Pyroclastic Density Currents, Geological Society of London Special Publication, 32 p text, 3 tables, 12 figures.

Elson, M.D., Ort, M.H., Anderson, K.C., submitted, Sunset Crater and Little Springs Volcano eruptions: Hazards management in the 11th century A.D. prehistoric Southwest; University of Colorado Press, 45 p text, five figures.

Valentine, G.A., Ort, M.H., Cortés, J.A., Hintz, A.R., submitted, Probability of basaltic eruptions in volcanic fields of the southwestern USA – Initial hazard assessment; Geology, 12 pages, 2 tables, 1 figure, 1 dataset for repository.

Ort, M.H., de Silva, S.L., Jiménez C., N., Jicha, B.R., Singer, B.S., in press, Correlation of Ignimbrites Using Characteristic Remanent Magnetization and Anisotropy of Magnetic Susceptibility, Central Andes, Bolivia; Geochemistry, Geophysics, Geosystems, 31 p text, 3 tables, 6 figures.

Elson, M.D., Ort, M.H., and Heidke J.M., in press, Effects  of the ca. A.D. 1100  Sunset  Crater eruption on local populations, northern Arizona. In Proceedings of the 2002 Chacmool Conference, Calgary, Alberta. University of Calgary, Alberta, Canada, 20 manuscript pages.

Elson, M.D., Ort, M.H., 2012, Fire in the sky: The eruption of Sunset Crater Volcano, in Downum, C., ed., Hisatsinom: Ancient peoples in a land without water. School for Advanced Research, Santa Fe, p. 26-33.

Elson, M.D., Ort, M,H., Anderson, K.C., Heidke, J.M., Sheppard, P.R., and Samples T.L., 2011, In the Shadow of the Volcano: Prehistoric Settlement in the U.S. 89 Project Area. In M.D. Elson (ed.) Sunset Crater Archaeology: The History of a Volcanic Landscape. Prehistoric Settlement in the Shadow of the Volcano, Anthropological Papers No. 37, Center for Desert Archaeology, Tucson, p. 187-211. 

Elson, M.D., Ort, M.H., Sheppard, P.R., Samples, T.L., Anderson, K.C., May, E.M., and Street, D.J., 2011, Sunset Crater Volcano. In M.D. Elson (ed.) Sunset Crater Archaeology: The History of a Volcanic Landscape. Prehistoric Settlement in the Shadow of the Volcano, Anthropological Papers No. 37, Center for Desert Archaeology, Tucson, p. 103-129.

For a complete list of publications and additional information, please download Michael Ort's CV.