School of Earth and Sustainability
PO Box 4099
Northern Arizona University
Flagstaff, AZ, 86011 USA
I am an emeritus professor in SES and taught both geology and environmental sciences courses. I am no longer able to take on graduate students, but serve as a member of thesis committees for students at NAU and elsewhere.
My research, which is described in more detail below, focuses on volcanoes. I am particularly interested in a) human adaptations to cinder-cone eruptions, b) phreatomagmatic processes (explosive water/magma interactions), c) pyroclastic flows and eruptions, d) environmental effects of eruptions, including chemical cycling, and e) crustal ascent processes (mostly using petrology and geochemistry as tools).
I was also the sciences and engineering faculty coordinator for the Interdisciplinary Global Programs, in which students complete two majors (a science/engineering degree and a language/culture degree) and spend a year abroad studying in their new language. I heartily recommend the IGP (https://nau.edu/igp/).
My research interests are diverse, but center on volcanoes.
I study volcanoes, with particular interest in the processes of pyroclastic currents and in magmatic processes in the crust. This work often involves careful fieldwork, paleomagnetism, and geochemistry. My goals are to better understand explosive processes at volcanoes so that we can better protect the public from volcanic hazards.
I have several ongoing projects:
Hopi Buttes (Tsezhin Bi'i) of NE Arizona: These are nephelinitic/monchiquitic (weirdo rocks!) volcanoes that formed maars, tuff rings, and tuff cones, as well as some spatter cones. The area was the site of a large playa in Miocene time, and the volcanoes erupted through saturated sediments. The exposures are fantastic, and my graduate students and I investigate the phreatomagmatic eruption processes and sedimentary history of the area. Facies analysis allows us to determine how the pyroclastic currents changed character out from the vent, while vent facies analysis allows us to understand the processes of magma-water interaction better. Anisotropy of magnetic susceptibility studies are helping us determine the depositional processes from the surges. Water-magma interactions are very common, but we do not understand why they occur in some eruptions but not in others, even at the same volcano. We need to understand how magma and water interact explosively in order to be able to define hazards.
Mexico: I work with Gerardo Carrasco-Núñez on several Recent maar volcanoes in the Serdán-Oriental basin in the eastern part of the Central Volcanic Belt of Mexico. We have been studying vent migrations at several maars, including Tecuitlapa and Atexcac. My student, Allison Austin, studied a rhyolitic maar, Tepéxitl, in great detail and then extended her study of rhyolite/water interaction processes while on a Fulbright scholarship in Germany. She worked with Bernd Zimanowski carrying out explosion simulations using magmas from Tepéxitl.
San Francisco volcanic field around Flagstaff: I work with volcanologists, archaeologists and geomorphologists to study the interactions of humans and volcanoes at very young scoria cones in southwestern North America, including Sunset Crater, Little Springs, Paricutin, and Jorullo. Scoria cones are small-ish volcanoes that affect limited areas, but we have found that, because they commonly form where people are living, their effects on humans can be significant. We have found evidence of human interactions with the eruptions themselves (offerings of corn and ceramic sherds), use of the lava flows for defensive purposes and caching water, as well as evidence of changes in agricultural practices in adaptation to the eruptions.
Italy: In addition, I have been working in the Campi Flegrei area of southern Italy for ~30 years, studying the pyroclastic deposits associated with the ~39 ka Campanian Ignimbrite/Museo Breccia/Piperno Tuff eruption. I have a collaboration studying the source of the gas in the Campanian Ignimbrite, with Victoria Smith at Oxford University, Guido Giordano at Universita di Roma Tre, and Roberto Isaia at Osservatorio Vesuviano.
Some Publications (Last 15 Years or so)
I can send pdfs of many of these papers upon request. I also have several manuscripts submitted, so those may be available soon.
Haag, M.B., Sommer, C.A., Savian, J.F. Caselli, A.T., Moncinhatto, T.R., Hartmann, G.A., Ort, M.H., Poletti, W., Ferreira da Trindade, R.I., 2021, AMS and rock magnetism in the Caviahue-Copahue Volcanic Complex (Southern Andes): Emission center, flow dynamics, and implications to the emplacement of non-welded PDCs; Journal of Volcanology and Geothermal Research, v. 416, 107283, doi:10.1016/j.jvolgeores.2021.107283.
Silleni, A., Giordano, G., Isaia, R., Ort, M.H., 2020, The magnitude of the 39.8 ka Campanian Ignimbrite eruption, Italy: Method, uncertainties and errors, Frontiers in Earth Science, v. 8, 22 p., 543399, doi:10.3389/feart.2020.543399.
Elson, M.D., Ort, M.H., Sheppard, P.R., Samples, T.L., Anderson, K.C., 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.
Anderson, E.S., Ort, M.H., Oldenburg, C.M., 2020, Thermo-hydrologic processes in maar eruptions: The role of vapor transport and condensation; Journal of Volcanology and Geothermal Research, v. 393, 106809, https://doi.org/10.1016/j.jvolgeores.2020.106809.
De León B., L., Carrasco Núñez, G., Ort, M.H., 2020, Stratigraphy and evolution of the Holocene Aljojuca Maar volcano (Serdán-Oriental basin, Eastern Transmexican Volcanic Belt), and implications for hazard assessment; Journal of Volcanology and Geothermal Research, v. 392, 106789, https://doi.org/10.1016/j.jvolgeores.2020.106789.
Riggs, N., Ort, M., Connor, C., Alfano, F., Conway, M., 2019, Volcanology and associated hazards of the San Francisco volcanic field, in Pearthree, P.A., ed., Geologic Excursions in Southwestern North America: Geological Society of America Field Guide 55, p. 127–146, https://doi.org/10.1130/2019.0055(05).
Alfano, F., Ort, M.H., Pioli, L., Self, S., Hanson, S., Clarke, A.B., Roggensack, K., Allison, C.M., Amos, R., 2019, The sub-Plinian monogenetic basaltic eruption of Sunset Crater, Arizona, USA; Geological Society of America Bulletin, v.131, p. 661-674.
Elson, M.D., Ort, M.H., 2018, Archaeological volcanology; in Encyclopedia of Archaeological Sciences, S.L. Lpez Varela (ed.), John Wiley & Sons, Inc., 5 p., DOI: 10.1002/9781119188230.saseas0041
Ort, M.H., Lefebvre, N.S., Neal, C.A., McConnell, V.S., Wohletz, K.H., 2018, Linking the Ukinrek 1977 maar-eruption observations to the tephra deposits: new insights into maar depositional processes; Journal of Volcanology and Geothermal Resources, v. 360, 36-60, doi 10.1016/j.jvolgeores.2018.07.005.
van Otterloo, J., Ort, M.H., Cruden, A.R., 2018, Unique occurrence of a folded in-vent dike: New insights on magma-water mixing; Geology, v. 46, p. 379-382, doi.org/10.1130/G39794.1
Re, G., White, J.D.L., Muirhead, J.D., Ort, M.H., 2016, Subterranean fragmentation of magma during conduit initiation and evolution in the shallow plumbing system of the small-volume Jagged Rocks volcanoes (Hopi Buttes Volcanic Field, Arizona, USA); Bulletin of Volcanology, v. 78:55, DOI 10.1007/s00445-016-1050-3.
Elson, M.D., Ort, M.H., Anderson, K.C., 2016, Sunset Crater and Little Springs Volcano eruptions: Disaster management in the Eleventh-century A.D. Southwest; in Herhahn, C.L., and Ramenofsky, A.F. (eds.), Exploring Cause and Explanation: Historical Ecology, Demography, and Movement in the American Southwest, University of Colorado Press, Boulder, p. 47-72.
Muirhead, J.D., Van Eaton. A.R., Re, G. White, J.D.L, Ort, M.H., 2016, Monogenetic volcanoes fed by interconnected dikes and sills in the Hopi Buttes volcanic field, Navajo Nation, USA, Bulletin of Volcanology, v. 78:11, p. 1-16.
Ort, M.H., Di Muro, A., Michon, L., Bachlery, P., 2016, Explosive eruptions from the interaction of magmatic and hydrothermal systems during flank extension: The Bellecombe Ashes of Piton de La Fournaise (La Runion Island), Bulletin of Volcanology, v. 78, p. 1-14.
Unema, J.A., Ort, M.H., Larsen, J.F., Neal, C.A. Schaefer, J.R., 2016, Water-magma interaction and plume processes in the 2008 Okmok eruption, Geological Society of America Bulletin, v. 128, p. 792-806.
Soriano, C., Beamud, E., Garcs, M., Ort, M.H., 2015, ԁnomalousՠmagnetic fabrics of dikes in the stable single domain/superparamagnetic threshold, Geophysical Journal International, v. 204 (2):1040-1059.
Re, G., White, J.D.L., Ort, M.H., 2015, Dikes, sills, and stress-regime evolution during emplacement of the Jagged Rocks Complex, Hopi Buttes Volcanic Field, Navajo Nation, USA, Journal of Volcanology and Geothermal Research, v. 295, p. 65-79, doi: 10.1016/j.jvolgeores.2015.01.009.
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., Jimnez 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., 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.
Salisbury, M.J., Jicha, B.R., de Silva, S.L., Singer, B.S., Jimnez-C., N., Ort, M.H., 2011, 40Ar/39Ar chronostratigraphy of Altiplano-Puna Volcanic Complex ignimbrites reveals the development of a major silicic magmatic province; Geological Society of America Bulletin, v. 123, p. 821и40, doi: 10.1130/B30280.1.
Austin-Erickson, A., Ort, M.H., Carrasco-Nez, 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., May, E.M., Ort, M.H., Anderson, K.C., Elson, M.D., 2010, Dendrochronological responses to a tornado. in Stoffel, M., Bollschweiler, M., Butler, D.R., Luckman, B.H. (eds.), Tree-Ring analysis in natural hazards research: A state-of-the-art, Advances in Global Change Research 41, Springer: Heidelberg, London, New York, p. 305г07.
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-Nez, 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., Vzquez-Selem, L., Clemens, A.W., Little, N.C., and Speakman, R.J. 2008. Multiple dendrochronological signals indicate the eruption of Parcutin Volcano, Michoacn, Mexico. Tree-Ring Research 64(2):97-108.
Austin-Erickson, A., Bttner, 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.
Hooten, J.A., Ort, M.H., and Elson, M.D., 2007, Chapter 6. The origin of cinders in Wupatki National Monument, in Elson, M.D., [ed.], Sunset Crater archaeology: The history of a volcanic landscape. Environmental analyses, Anthropological Papers No. 33, Center for Desert Archaeology, Tucson, p. 77-85.
Hooten, J.A., and Ort, M.H., 2007, Chapter 7. Sunset Crater tephra mapping project: The creation of an isopach map, in Elson, M.D., [ed.], Sunset Crater archaeology: The history of a volcanic landscape. Environmental analyses, Anthropological Papers No. 33, Center for Desert Archaeology, Tucson, p. 87-93.
Ort, M.H., Elson, M.D., and Champion, D.E., 2007, Chapter 8. A paleomagnetic dating study of Sunset Crater, in Elson, M.D., [ed.], Sunset Crater archaeology: The history of a volcanic landscape. Environmental analyses, Anthropological Papers No. 33, Center for Desert Archaeology, Tucson, p. 95-102.
Elson, M. D., Ort, M.H., Anderson, K.A., and Heidke, J.M., 2007, Living with the volcano: the 11th century A.D. eruption of Sunset Crater. In Living under the shadow: Cultural impacts of volcanic eruptions: Walnut Creek, Left Coast Press, p. 107б32.
Carrasco-Nuez, G., Ort, M.H., and Romero, C., 2007, Anatomy of a maar volcano: Case study of Atexcac crater, eastern Mexico; Journal of Volcanology and Geothermal Research, v. 159, p. 179-197.
Elson, M.D., Ort, M.H., and Philips, B.G., 2006, Environmental Setting, in Elson, M.D., [ed.], Sunset Crater Archaeology: The history of a volcanic landscape. Introduction and site descriptions, Anthropological Papers No. 30, part 1, Center for Desert Archaeology, Tucson, p. 17-42.
Vazquez, J.A., and Ort, M.H., 2006, Facies variation of eruption units produced by the passage of single pyroclastic surge currents, Hopi Buttes volcanic field, USA; Journal of Volcanology and Geothermal Research, 154:222в36.
Duffield, W., Riggs, N., Kaufman, D., Champion, D., Fenton, C., Forman, S., McIntosh, W., Hereford, R., Plescia, J., and Ort, M., 2006, Multiple constraints on the age of a Pleistocene lava dam across the Little Colorado River at Grand Falls, Arizona; Geological Society of America Bulletin, 118:421-429.
Ort, M.H., Anderson, D.E., and Ostergren, D.M., 2006, Integrating Policy and Land Management Issues into a Natural Sciences Education: Teaching Environmental Sciences on the lower San Juan River, Utah, Journal of Geoscience Education, v. 53, p. 116-122.
I have a spinner magnetometer and an AF demagnetizer, which my students and I use for standard paleomagnetic studies and secular variation studies of volcanic deposits, which is especially useful for dating young volcanic units. I also have an AGICO Kappabridge KLY-4 on long-term loan that we use for anisotropy of magnetic susceptibility studies.
The SES home page, where you can find information on the academic programs, is
created by Michael Ort, michael.ort(at)nau.edu