[unav_all] "Seismology in Alaska" webinar rescheduled for 11/1
andyf at iris.edu
Tue Oct 15 09:59:15 MDT 2013
Sorry for the delay everyone...
The next IRIS webinar highlights "Seismology and Imaging beneath Alaska:
EarthScope’s Final Frontier" from 2-3 pm ET (7-8 pm UTC) on Friday 11/1.
Following the main webinar, I (Andy Frassetto) will provide a brief
update on the test TA stations currently deployed in Alaska and the
Yukon and preliminary plans for the 2014 EarthScope Transportable Array
Deployments in Alaska.
Register to attend: https://www2.gotomeeting.com/register/574155874
You will be emailed a confirmation containing a link for accessing the
webinar. The presentation and subsequent interactions between the
speaker, host, and audience are recorded and made available within a few
days. Access to the webinar archive, along with related materials and
more information on the series is found here:
Presenter: Dr. Geoff Abers, Lamont Research Professor, LDEO, Columbia
Alaska is home to most of North America’s earthquakes, including the
second largest ever recorded (Mw 9.2). It is also a place where
subducting plates traverse the upper mantle, driving abundant magmatism
in an arc nearly 3000 km long. From now through 2018, the Transportable
Array will site, deploy and operate stations throughout Alaska,
completing the coverage of the continental United States. Likely the TA
will be supplemented by portable seismic deployments and by other
related activities onshore and offshore. All of these build on knowledge
from a small number of past experiences in the area, which provide clear
evidence of the wealth of scientific opportunities and special
challenges working in this harsh environment. I will provide an overview
of some past experiments and projects, highlighting several for which I
have personal experience.
A couple lessons emerge. First, seismicity is remarkably abundant, and
constitutes the vast majority of earthquakes in the U.S. Besides the
signals, such high seismicity levels present operational challenges.
Second, the subduction zone produces considerable structure within the
upper mantle, precisely where broadband arrays can provide the most
information about the Earth. In two past experiments (BEAAR and MOOS) we
mapped out the subducting crust and plate interface zone from near the
trench to 130 km depth, over several hundred km, and observe hints of
many other structures. At this scale, the TA is guaranteed to image a
great deal of interesting structure, and focused experiments have even
more promise. Third, logistics are challenging but not insurmountable if
projects are well designed and logistical constraints are taken into
account in their design. Road systems are sparse but exist in some parts
of the state, and airstrips exist in many others, although helicopters
are clearly necessary in many regions. Finally, many problems associated
with great earthquakes and volcanism will require coordinated marine
programs, since the plate boundary system does not stop at the coastline
and the Aleutians are small islands. Ocean-bottom seismometers can play
a critical role in both the thrust zone and around remote segments of
the volcanic arc.
Overall, the arrival of USArray has tremendous potential to reveal
fundamental properties of the nature of subduction beneath continents.
Andy Frassetto (andyf at iris.edu) can be contacted with any inquiries.
Required: Windows® 7, 8, Vista, XP or 2003 Server
Required: Mac OS® X 10.5 or newer
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