The University of New Brunswick is studying earthquake
activity in the Maritimes thanks to the recent purchase of a seismograph.

Seismographs record the arrival of seismic waves from earthquakes
by measuring voltages generated when ground movements cause electrical coils to
move relative to magnetic masses suspended on springs.

UNB alumni may recall an old seismograph that was installed
on campus near the Science Library as part of the Canadian National Seismograph
Network until the mid-1990s.  That
instrument, with its classic pen-on-paper drum recorder, was retired when its
technology, together with its location in the midst of a busy campus, rendered
it unable to meet increasing standards for data quality. 

Through generous donations to UNB, contributed by the McLeod
family of Vancouver and alumnus Graham Farquharson, and UNB staff efforts, the
university has purchased a new observatory-grade instrument.

Faculty and students are in the process of commissioning it
this summer. Data are already being collected at a temporary station and being
relayed over internet connections to both UNB Fredericton and Earthquakes
Canada in Ottawa. 

“Our next short term goal”, says Karl Butler, professor of
earth sciences, “is to display the incoming seismograph data live, on campus.
The Quartermain Earth Science Centre gives us a great environment to wrap all
this inside and present the data to the public. We also expect to make a live
display accessible through our departmental web site.”

Monitoring a Mystery
in McAdam 

Coincidently, UNB has been working with Earthquakes Canada
seismologists to study unusual earthquake activity in McAdam, New Brunswick
since mid-March. UNB’s new instrument is temporarily stationed there along with
two others from Ottawa in an effort to understand the seismic source.

“McAdam has experienced at least 30 small seismic events,
constituting what is known as an earthquake swarm” Butler says. “Following an
early flurry, the earthquakes have become more sporadic since mid-April, but
there have been some occurring as recently as mid-June.” Although small in size
(the largest had a magnitude of 2.4), the events have been unnerving for
residents who described them as sounding like explosions. Monitoring has
revealed that the quakes are occurring at very shallow depths, directly under
the town, explaining why the seismic waves are sufficiently high in frequency
to be heard as much as felt.

A permanent site for UNB’s seismograph, in a quiet location
on bedrock, is being sought in central New Brunswick, where Butler notes there
is currently a gap in the Canadian National Seismograph Network. Sites near
Minto and Mactaquac are both under consideration.

Butler says that either location could serve as a good
bedrock reference site for estimating seismic wave amplification effects that
are known to occur in the thick soft sediments of the St. John River valley.

These amplification effects – the subject of a recent Team
Design Project by UNB Geological Engineering students – increase seismic risk
in downtown Fredericton as evidenced by the swaying of buildings that occurred
there during the magnitude 5.8 Virginia earthquake of August 23, 2011.  

“Hopefully this will give us a reference site on bedrock
near Fredericton that we can use to compare to the ground motions in the city,”
says Butler. “That’s a longer-term project we’d like to work on as well that
would involve students.”

Benefiting student
research

Jessie Brown, a third-year undergraduate student at UNB, was
the recipient of a National Science and Engineering Research Council award, and
is interning with Butler’s team. She is helping to set up software for
operating the seismograph and displaying its data to campus, and is also
participating in analysis of the McAdam earthquake swarm.

“Ultimately, we hope to have the seismograph project set up
in such a way that we can bring the data into classrooms to show students
examples of what’s coming in right now and examples of earthquakes that have
been measured at Fredericton,” says Butler.

Having a live feed from a seismograph on display within the
Quartermain Earth Science Centre, Butler says is a great way of showing people
that the earth is always moving.

“While our current educational seismograph has been a very
popular attraction, this new observatory-grade instrument will reveal far more
seismic activity,” he says. “In terms of research, it opens up possibilities
for UNB students to get more involved in earthquake seismology.”

Contributed by Bronté James, Communications
and Marketing. Story
was made possible through UNB Associated Alumni