[CIG-ALL] IRIS WEBINAR - Anatomy of a Megathrust Earthquake Rupture: The 2010 M8.8 Chile Quake - 4/9, 1 PM Eastern

[Andy Frassetto]

"Anatomy of a Megathrust Earthquake Rupture: The 2010 M8.8 Chile Quake" 
will be presented at 1 pm EDT (5 pm UTC) on Wednesday, 4/9.

Please registerif you intend to join the webinar live: 
https://www2.gotomeeting.com/register/787452210

You will be emailed a confirmation containing a link for watching the 
live broadcast. Afterwards, a recording will be posted here: 
http://www.youtube.com/user/IRISEnO. Access to older webinars, along 
with related materials and information is found here: 
http://www.iris.edu/hq/webinar/

Presenter: Stephen P. Hicks, Postgraduate Research Student, University 
of Liverpool, UK.

Abstract: In February 2010, a magnitude 8.8 megathrust earthquake struck 
the Maule region of Central Chile - the sixth largest earthquake ever 
recorded. It is fast becoming one of the best-studied megathrust 
ruptures, allowing us a unique insight into the inner workings of 
subduction zone earthquakes. In the earthquake's immediate aftermath, an 
international group of research institutions deployed geophysical 
instruments in the rupture area. A network of ~160 seismic stations on 
the forearc recorded over 50,000 aftershocks in the first 10 months 
following the earthquake.

I have used observations of P- and S-waves from aftershocks to derive a 
high-resolution seismic travel-time tomography of the rupture zone. 
Observations from ocean-bottom seismometers further improve image 
sharpness in the offshore portion of the seismogenic zone, where most 
slip occurred during the earthquake. The tomographic images reveal the 
distribution of P-wave velocity and Poisson's Ratio within the 
earthquake rupture zone. Based on accurate aftershock locations and 
moment tensors, I have defined a new 3-D plate interface geometry to 
infer the physical structure and composition along the plate interface. 
I compare these velocities with the mainly geodetically observed 
behaviour of the fault throughout a cycle of seismic behaviour 
(preseismic locking, coseismic slip, postseismic deformation). This 
comparison allows us to understand some of the physical properties that 
may govern seismogenesis along the megathrust. I will reveal how both 
the long-lived geological structure of the forearc and the composition 
of the subducting oceanic plate may influence the rupture behaviour of 
large megathrust earthquakes. An understanding of seismic velocities 
along the megathrust may therefore be used to constrain the seismogenic 
potential of subduction zones worldwide.


System Requirements
PC-based attendees: Windows® 8, 7, Vista, XP or 2003 Server
Mac®-based attendees: Mac OS® X 10.6 or newer
Mobile attendees: iPhone®, iPad®, Android^(TM) phone or Android tablet
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