Dynamic
duo have explosive careers
Timothy
and Jacqueline Dixon enjoy occasional outbursts. As husband and wife professors
at the Rosenstiel School of Marine and Atmospheric Science, they share a
unique love-for volcanology, the study of volcanoes.
 Though their zeal in seeking to
understand these temperamental mountains is mutual, their motivation is
not. Tim is fascinated by the consequences of a volcano's great destructive
power, whereas Jackie's work is focused on understanding the causal factors
behind the eruption.
"Something will trigger that volcano to wake
up and erupt," says Jackie. "My research is understanding how
much gas is dissolved in the magma, and the conditions present at the time
of an eruption."
When she lectures, her main visual aid is often
a bottle of champagne, which gushes similarly to a volcano. Like champagne,
magma has carbon dioxide and water dissolved in itbut deep within the
earth, where it is formed. As the magma slowly comes to the surface, bubbles
form. "Whether those bubbles escape or stay in the magma and increase
the pressure is a big question linked to why and how a volcano erupts,"
says Jackie.
A big question for Tim is whether or not the surface
of a volcano moves rapidly just prior to a major cataclysmic eruption. He
believes the answer is yes. By measuring volcano surface motion he hopes
to ultimately predict eruptions.
"Tim made the first measurements ever on a
volcano in 1985 using the Global Positioning System (GPS)," says Jackie.
"Tim uses satellites to measure how the surface of the volcano is moving
in almost real time."
GPS is a military satellite-based navigation system
that Tim, through funding mostly from NASA, customized specifically to study
ground deformation around active volcanoes. Though there are other techniques
that measure displacement, the significant advantages of GPS are its accuracy;
automated, remote operation; and relatively low cost.
"It's been difficult to deploy any other tools
on a volcano once it has become extremely active because it's too dangerous
to go up there," says Tim. "Last year four mountain climbers were
killed near one of our receivers on Popocatepetl." Known as Popo, Popocatepetl
is the second highest volcano in Mexico just 45 miles southeast of downtown
Mexico City. Volcanologists are drawn to Popo because of its extensive history
of eruptions, which tend to repeat.
"Popo is the most exciting thing we've worked
on during our five years at UM," says Jackie. "The last giant
eruption was 1,000 years ago, so it's coming into the window when another
large eruption is possible."
In describing their visit to Popo in January, eruptions,
albeit playful ones, surface between the Dixons. During the trip, Tim recovered
pieces of obsidian knife blades and pottery shards embedded in ash and pumice
from its last major eruption. "Basically this volcanic mud flow, or
lahar, roared down the mountain and inundated this village, leaving behind
a layer of artifacts," Tim says, "including skeletal remains."
"They did not find skeletal remains!"
Jackie interrupts. "They were able to get out in time."
He next points to a picture of Jackie high atop
a volcano, with crimson blasts shooting out over her head. "Here's
Jackie in an asbestos suit," he says.
"It's not asbestos!" she chides. "It's
simply a fire-retardant helicopter flight suit!" (Simply?)
He moves onto his next statement with ease, undaunted
by his wife's admonition. With his ever-so-slight grin, it's difficult to
discern whether he purposely makes these erroneous comments to get a rise
out of her, or if he was in fact mistaken.
"The combination of our limited data and lack
of really good models hinders volcanologists from predicting what the future
will bring," Tim says. Such is the predicament of the inhabitants of
Montserrat, the British colonial island recently plagued with devastating
eruptions from the Soufriere Hills volcano in the south.
Tim is actively involved in a project using GPS
on Montserrat in collaboration with the University of Puerto Rico. Though
one of the receivers was recently destroyed by hot ash, another is still
operating. However, the damaged infrastructure on the island has made it
difficult to retrieve consistent data, which is transmitted over telephone
lines.
"If we were living there, we would have moved
some time ago," says Tim, "because of the risk of a major eruption
and the medical problems from the dust. I wouldn't want our eight-year-old
son breathing that in."
Their son, Ian, goes along on many trips, "but
we don't push [our field] on him," says Jackie.
"We try to get him uninterested," Tim
jokes.
That seems impossible from either parent, as both
talk with great enthusiasm about their work. They are frequently invited
to speak at elementary schools, and Jackie is particularly excited about
her involvement with the undergraduate geology department. This is her fourth
year teaching an undergraduate geology course, and she has participated
for the last two years in the summer field course of Harold Wanless, professor
of geological sciences.
She hopes to take an undergraduate along on an
upcoming trip to Cape Town, South Africa, and is organizing a field trip
to Popo during spring break 1999. "That's how I got my start,"
says Jackie. "Getting out of the classroom is the best way to really
get involved." | 
Recently awarded Poet of Merit 1997 by the International
Society of Poets, Severdija is receiving acclaim long overdue. For years
she had been jotting down poems and storing them for sentimental reasons,
never giving them much thought nor having the heart to throw them away.
Almost two years ago, she shared some poems with a friend to whom she had
casually mentioned her pastime.
