[unav_all] Reminder: "Seismology in Alaska" webinar Friday 11/1

Andy Frassetto andyf at iris.edu
Tue Oct 29 12:01:08 MDT 2013

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, Andy Frassetto (IRIS Seismology Swiss Army 
Knife) 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.

Any inquiries can be directed to Andy (andyf at iris.edu).

System Requirements
PC-based attendees
Required: Windows® 7, 8, Vista, XP or 2003 Server
Macintosh®-based attendees
Required: Mac OS® X 10.5 or newer

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