Talking
rocks on the San Juan River, as part of the course Environmental Sciences
of the lower San Juan River
Michael Ort
School
of Earth Sciences and Environmental Sustainability
PO Box 4099
Northern Arizona University
Flagstaff, AZ, 86011 USA
928-523-9363 phone
928-523-9220 fax
http://jan.ucc.nau.edu/~mho
I am a professor within the SESES and teach
both geology and environmental sciences courses. 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).
Teaching
I teach courses in both Environmental
Sciences and Geology.
Environmental Sciences: Generally, I teach ENV 385, Energy, Resources, and
Policy, the last course in the ENV core series, in the spring, and either ENV
101, an introduction to environmental sciences, or ENV 280, Chemistry and
Physics of the Environment in the fall semester. Over the years, I have taught most of the environmental
sciences courses at least once. I
created the course Environmental Sciences of the San Juan River (ENV 375) a few
years ago and continue to be involved in it, including the eight-day river
trip.
Geology: In Geology, I teach undergraduate courses in geologic disasters (GLG
112), introduction to field mapping (GLG 240), igneous and metamorphic
petrology (GLG 315), and graduate courses in volcanology and igneous petrology
(GLG 610 and 612).
2002
ENV 385 Resources and Policy class at Black Mesa Mine, Navajo Nation. Photo
courtesy of Dave Ostergren.
1996 Graduate Volcanology class looking
at maar deposits in the San Francisco volcanic field. Photo courtesy of
Todd Keay.
Class Home Pages
This fall, I am teaching
ENV 280, Chemistry and
Physics of the Environment (syllabus)
GLG 101 Physical Geology
(class home page)
Research
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.
Typically, this 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 are
investigating 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. I would like to work with
other students on processes of water-magma interactions, flow processes, and
petrology at the Hopi Buttes.
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 am working 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, Tepexitl, 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
Tepexitl.
In the San Francisco
volcanic field around Flagstaff, I am working with archaeologists and
geomorphologists on a project studying the impact of the ~900 y.b.p. eruption of Sunset Crater on the people living here at that
time. This project has expanded to
studying the interactions of humans and volcanoes at other very young scoria
cones in southwestern North America, including Little Springs, Parcutin, and
Jorullo. Scoria cones are relatively
small 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.
In addition, I
have been working in the Campi Flegrei area of southern Italy for a number of years,
studying the pyroclastic deposits associated with the ~40 ka Campanian
Ignimbrite/Museo Breccia/Piperno Tuff eruption. There, in collaboration with
Giovanni Orsi and Mauro Rosi, I have mostly been doing anisotropy of magnetic
susceptibility studies to determine how the currents deposited the tuffs. We are now working on resurgence
dynamics in the caldera formed by the Monte Epomeo Green Tuff eruption about
55,000 years ago. I also have a collaboration with Guido Giordano and Anna Paula Vinkler
on the initiation of the Tufo Lionato eruption of the Colli Albani outside of
Rome.
Dendrochemical
dating of eruptions: My colleagues,
Paul Sheppard (dendrochronologist at University of Arizona) and Mark Elson
(Desert Archaeology) and I have been developing a new way of dating young tephra-producing
eruptions. We are analyzing the
chemical changes in tree rings caused by eruptions. We are finding that trees take in different chemicals when
their roots are covered by tephra, and we can detect this using the ICP-MS at
NAU. This technique appears to
work well with cinder cones, and we are hoping to apply it to other types of
volcanoes. Currently, we are
attempting to date the Sunset Crater and Cinder Cone (Lassen Volcano National
Park) eruptions with this technique.
Colleen Donegan, an MS student working with me, is applying the
technique to Mount St. Helens.
Kathy Cashman, of University of Oregon, and I received NSF funding to study
the 800 BP eruption of Quilotoa volcano in Ecuador.
We are working with Patty Mothes and Jorge Bustillos of the Instituto
Geofísico in Quito, Andrea di Muro of the Reunion Observatory, and Mauro Rosi
of the Universitá di Pisa. It
produced two large ignimbrite-forming eruptions 800 years ago, with a
several-week-long hiatus between them.
The second eruption began by producing a few surges and then an odd, very-crystal-rich fallout that is distributed for
about 15 km radius around the vent.
How did this crystal fallout form, and what does it tell us about the
eruption dynamics?
Recent Publications
I can send pdfs of
many of these papers upon request.
I also have several manuscripts submitted, so those may be available
soon.
Ort,
M.H., in press, The eruption of Sunset Crater volcano;
in Elson, M.D. [ed.], Sunset Crater archaeology: Prehistoric settlement in the
shadow of a volcano. Center for Desert Archaeology Anthropological Papers No. 37, 15
manuscript pages.
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 Cinder Cone Eruptions upon Nearby Human
Communities, Geological Society of America Bulletin, p. 476-486.
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. 107–132.
Carrasco-Núñez,
G., Ort, M.H., and Romero, C., 2006, Anatomy of a maar volcano: Case
study of Atexcac crater, eastern Mexico; Journal of Volcanology and Geothermal
Research, v. 159, p. 179-197.
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, 154:222–236.
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.
Sheppard,
P.R., May, E., Ort, M.H., Anderson, K., Elson, M.D., 2005,
Dendrochronological responses to the 24 October 1992 tornado at Sunset Crater,
northern Arizona; Canadian Journal of Forest Research, 35:2911-2919.
Dallegge,
T.A., Ort, M.H., McIntosh, W.C., 2003, Mio-Pliocene chronostratigraphy,
basin morphology and paleodrainage relations derived from the Bidahochi
Formation, Hopi and Navajo Nations, northeastern Arizona: The Mountain
Geologist, v. 40, no. 3, pp. 55-82.
Ort,
M.H., Orsi, G., Pappalardo, L., and Fisher, R.V., 2003, Anisotropy of magnetic
susceptibility studies of depositional processes in the Campanian Ignimbrite,
Italy; Bulletin of Volcanology, 65:55-72.
Elson, M.D., Ort,
M.H., Hesse, S. J., Duffield, W.A., 2002, Lava, corn, and ritual in the
northern Southwest; American Antiquity, 67:119-135.
Hooten, J.A., Ort, M.H., 2002, Peperite as a Record
of Early Stage Phreatomagmatic Fragmentation Processes: An Example from the
Hopi Buttes Volcanic Field, Navajo Nation, Arizona, USA, Journal of Volcanology
and Geothermal Research, 114:95-106.
Ort, MH, Elson, MD, and Champion, DE, 2002, A paleomagnetic
dating study of Sunset Crater Volcano; Desert Archaeology, Inc. Technical
Report No. 2002-16, 16 p.
Laboratories
Isotope laboratory
I have a well-equipped isotope clean lab, in
which my students and I conduct a number of projects. The lab has two large
laminar flow workstations for column chemistry, two HEPA-filtered clean hoods
with two-bottle stills and evaporation plates, a fume hood, an oven, a
centrifuge, a balance, and a DI water system. It is set up so that we can do
all the preparation of geologic and biologic samples for high-precision
geochemical analysis. A group of
researchers at NAU, including me, have a nine-collector Axiom ICP-MS
(inductively coupled plasma mass spectrometer), thanks to a grant from NSF, as
well as a recently purchased quadrapole ICP. We can analyze for most elements on this instrument, as well
as a number of different isotopes.
A laser-ablation unit and a microsampling drill are recently funded
additions to the ICP-MS laboratory.
Sr, Nd, Hf, and Pb isotopic analysis is done either on NAU’s ICP-MS or
at University of California. This
arrangement allows us to do the time-consuming work here, and then either send
the samples for analysis or go out to California and spend a few days analyzing
many samples.
Paleomagnetism Laboratory
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. Currently, we are dating
some Holocene flows in the Southwestern USA using secular variation.
Other Laboratories
The department has an electron microprobe for mineral analysis, as well as a
well-equipped particle-size analysis laboratory. A scanning electron microscope, funded by NSF, has just been
installed. My students and I will
use it for grain shape analysis and many other purposes.
Commission on Explosive Volcanism
I
was one of the two leaders of the CEV, and was keeper of the home page. After
four years, I stepped down from this position. Shinji Takarada is now running the site. To find out more about it, go to http://staff.aist.go.jp/s-takarada/CEV/
Some Related Pages
Several
other professors do volcano-related work at NAU:
Nancy
Riggs,
Professor, is a volcanologist: http://jan.ucc.nau.edu/~nrr/nrr.html
Mary Reid,
Professor, is an isotope geochemist who studies magmatic timescales. Her email address is mary.reid@nau.edu.
Jim
Wittke,
Supervisor, Microprobe Lab: http://oak.ucc.nau.edu/wittke/
Wendell
Duffield, retired from the USGS, serves on many graduate thesis committees
and is actively involved in the volcanology courses. http://oak.ucc.nau.edu/wad3
The Geology
Dept. home page is http://www4.nau.edu/geology
The Center
for Environmental Sciences and Education home page is http://www.nau.edu/envsci/
Marisa
My daughter, Marisa, is the most
beautiful girl in the world. By popular demand, I have given her a photo corner
created by Michael Ort, michael.ort@nau.eduNOSPAM
Dept. of Geology and Center for Environmental Sciences and Education, Northern Arizona University, Flagstaff, AZ 86011 USA
URL: http://jan.ucc.nau.edu/~mho