Dr. Michael H. Ort

Michael Ort 230px
Professor

Education

PhD, University of California

Contact

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 and scoria-cone volcanoes in Arizona, Alaska, and Italy. 

One driving question is how do 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. 

I have worked on scoria cones and maars for many years.  I am interested in learning what drives these eruptions, especially the explosivity, and in how water/mud and magma interact.  Many of my students work on these projects, as we can design MS-scale theses easily.  Typically, these theses combine field work with some quantitative laboratory analyses.

I am also currently working on the interaction between humans and the youngest volcanism in the Southwestern USA, concentrating on the ~1085 CE Sunset Crater eruption near Flagstaff and the Little Springs eruption (dated between 1050 and 1200 CE). 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.  We have developed innovative dating techniques for these eruptions in order to understand changes to the environment on human time scales, rather than just geologic time scales.

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.

Some Selected Publications

Elson, M.D., Ort, M.H., Anderson, K.C., in press, Sunset Crater and Little Springs Volcano eruptions: 
Disaster management in the 11th century A.D. 
prehistoric Southwest; in How, Why, and Beyond: Exploring Cause and Explanation in Historical Ecology, Demography, and Movement, Herhahn, C., and Ramenofsky, A.F. (eds.). University of Colorado Press, Boulder.. 50 p text, four figures.

Elson, M.D., Ort, M.H., Sheppard, P.R., Samples, T.L., Anderson, K.C., and May, E.M., in press, A.D. 1064 No More? A multidisciplinary re-evaluation of the date of the eruption of Sunset Crater volcano, northern Arizona; University of Utah Press, 68 p. 7 figures, 3 tables.

Ort, M.H., Porreca, M. & Geissman, J.W., 2015, Introduction to The use of palaeomagnetism and rock magnetism to understand volcanic processes: in Ort, M.H., Porreca, M. & Geissman, J.W. (eds) The use of palaeomagnetism and rock magnetism to understand volcanic processes. Geological Society, London, Special Publications, 396, p. 1-11, http://dx.doi.org/10.1144/SP396.17.

Ort, M.H., Newkirk, T.N., Vilas, J.F., Vazquez, J.A., 2015, Towards the definition of AMS facies in the deposits of pyroclastic density currents: in Ort, M.H., Porreca, M. & Geissman, J.W. (eds) The use of palaeomagnetism and rock magnetism to understand volcanic processes. Geological Society, London, Special Publications, 396, p. 205-226, http://dx.doi.org/10.1144/SP396.8.

Ort, M.H., de Silva, S.L., Jiménez C., N., Jicha, B.R., Singer, B.S., 2013, Correlation of ignimbrites using characteristic remanent magnetism and anisotropy of magnetic susceptibility, central Andes, Bolivia; Geochemistry, Geophysics, Geosystems, v. 14, p. 141-157, doi: 10.1029/2012GC004276.

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.

Austin-Erickson, A., Ort, M.H., Carrasco-Núñez, G., 2011, Rhyolitic phreatomagmatism explored: Tepexitl Tuff Ring (Eastern Mexican Volcanic Belt), Journal of Volcanology and Geothermal Research, v. 201, p. 325-341.

Sheppard, P.R., Ort, M.H., Anderson, K,C., Clynne, M.A., May, E.M., 2009, Multiple dendrochronological responses to the eruption of Cinder Cone, Lassen Volcanic National Park, California, Dendrochronologia, v. 27, p. 213-221.    

Ort, M.H., Carrasco-Núñez, G., 2009, Lateral vent migration during phreatomagmatic and magmatic eruptions at Tecuitlapa Maar, east-central Mexico, Journal of Volcanology and Geothermal Research, v. 181, p. 67-77, doi:10.1016/j.jvolgeores.2009.01.003.

Sheppard, P.R., Ort, M.H., Anderson, K.C., Elson, M.D., Vázquez-Selem, L., Clemens, A.W., Little, N.C., and Speakman, R.J. 2008. Multiple dendrochronological signals indicate the eruption of Parícutin Volcano, Michoacán, Mexico. Tree-Ring Research 64(2):97-108.

Austin-Erickson, A., Büttner, R., Dellino, P., Ort, M.H., and Zimanowski, B., 2008, Phreatomagmatic explosions of rhyolitic magma: Experimental and field evidence, Journal of Geophysical Research, 113, B11201, doi:10.1029/2008JB005731.

Ort, M.H., Elson, M.D., Anderson, K.C., Duffield, W.A., and Samples, T.L., 2008, Variable effects of cinder-cone eruptions on prehistoric agrarian human populations in the American Southwest, Journal of Volcanology and Geothermal Research, v. 176, p. 363-376.

Pioli, L., Lanza, R., Ort, M.H., Rosi, M., 2008, Magnetic fabric, welding texture and strain fabric in the Nuraxi tuff, Sardinia, Italy, Bulletin of Volcanology, v. 70, p. 1123-1137.

Ort, M.H., Elson, M.D., Anderson, K.C., Duffield, W.A., Hooten, J.A., Champion, D.E., and Waring, G., 2008, Effects of scoria-cone eruptions upon nearby human communities, Geological Society of America Bulletin, v. 120, p. 476-486.

 

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