Ge 277- Megathrust Earthquakes
Fall Quarter 2007
Instructor: Jean-Philippe Avouac
Fridays, 10:00-11:30pm, + 2 Wednesdays, 2:00-3:30,
Location: Gutenberg Library
Outline
In the wake of the recent large earthquakes in Sumatra and Peru,
we will discuss megathrust earthquakes. Based on the review of
the literature (see references below), we will try to identify
the key factors that might control the seismic potential of subduction
zone and the characteristics of large subduction earthquakes. During
the first seminar, the instructor will discuss observations of
interseismic and co-seismic strain along the Sumatra subduction
zone. After that introductory seminar we will review the literature
(see references below), each week being devoted to a new topic.
We will in particular discuss the following points:
- Is there any regularity or systematics in the way a particular
segment of subduction zone ruptures in successive earthquakes?
- How does the portion of a megathrust that is locked during the
interseismic period compares with the rupture area of large earthquakes?
- How does co-seismic slip compares with slip deficit accumulated
during the interseismic period?
- How variable is 'coupling' along the megathrust, both in time
and space.
- Correlation of earthquake size and rupture area to subduction
features.
At the end of the seminar series we will come back to the
discussion of Sumatra to see how the observations made there
contrast with what has already been described in the literature,
and what inference can be made regarding the 'seismic cycle' on
megathrust.
Organization.
We will be meeting once a week in the Gutenberg Library, generally
on Fridays from 10:00 pm to 11:30 pm (see schedule below).The instructor
will give the introductory lecture. Each student will be in charge
of presenting one or two topics to the group over the 10 weeks
course of the seminar. Each student will be asked to interact with
the instructor to prepare the presentation, at least one week ahead
of time. This is important to make it sure that the message is
well conveyed to the group and that the basic concepts necessary
to make the topic accessible to the audience are reviewed during
the presentation. Each week, we will pick one key paper that each
student is expected to have read ahead of time. The information
will be given the week before the presentation.
The ppt presentations, readings and additional papers are available
on JPA ftp site.
Friday, October 8
Topic: Interseismic strain accumulation co-seismic strain release on the Sumatra Megathrust. This introductory lecture will introduce the key questions to be discussed later during the seminar series.
Speaker: Jean-Philippe Avouac
Reading : [Thatcher, 1990]
Some references on Sumatra :
[Ammon, et al., 2005; Briggs, et al., 2006; Chlieh,
et al., 2005; Chlieh, et al., 2007; Hsu, et al.,
2006; Konca, et al., 2007; Lay, et al., 2005; Meltzner,
et al., 2006; Natawidjaja, et al., 2004; Natawidjaja,
et al., 2006; Newcomb and McCann, 1987; Sieh,
et al., 1999; Simoes, et al., 2004]
Friday, October 15
Topic : The rupture process of large subduction earthquakes The
asperity model and the slip-pulse model.
Speakers : Yoshi
Readings : [Aki, 1984]
Additional references:
[Dmowska and Lovison, 1992; Heaton, 1990; Igarashi,
et al., 2003; Lay, et al., 1982; Mikumo, et al.,
1998; Park and Mori, 2007; Schwartz and Ruff,
1987; Yagi, et al., 2001]
Friday, October 26
No class
Wednesday, October 31(2:00-3:30)
Topic : Are asperities and barriers long-lived or short-lived features?
Speakers : Ravi Kanda
Reading : [Wells, et al., 2003]
Additional references:
[Kodaira, et al., 2006; Kodaira, et al., 2000; Llenos
and McGuire, 2007; Park and Mori, 2007; Song
and Simons, 2003]
Friday, November 2
Topic : The time predictable and slip predictable models. How ‘regular’ is the ‘seismic cycle’? How valid is the seismic gap hypothesis?
Speaker : Belle
Readings : [Shimazaki and Nakata, 1980]
Additional references:
[Cisternas, et al., 2005; Kagan and Jackson,
1991; Schwartz, 1999; Shimazaki and Nakata, 1980; Sykes
and Menke, 2006; Thatcher, 1984]
Friday, November 9
Topic : ‘Seismic coupling’ and the depth distribution
of earthquakes along subduction zone.
Speaker : Carl
Readings : [Pacheco, et al., 1993]
Additional references:
[Igarashi, et al., 2001; Nakanishi, et al., 2004; Ruff
and Kanamori, 1983; Tichelaar and Ruff, 1993]
Friday, November 16
No Class
Wednesday, November 21 (2:00-3:30)
Topic: ‘Geodetic coupling’. How variable is 'geodetic coupling' along the megathrust, both in time and space? How does it compare to ‘seismic coupling’?
Speakers : Ting
Reading : [Burgmann, et al., 2005; Suwa, et al., 2006]
Additional references: [Chlieh, et al., 2004; Cross and Freymueller, 2007; Fournier and Freymueller, 2007; Freymueller, et al., 2000; Mazzotti, et al., 1999; Nishimura, et al., 2004; Taylor, et al., 1996; Wallace and Beavan, 2006; Wallace, et al., 2004; Zweck, et al., 2002]
Additional references:
[Hyndman, et al., 1997; Oleskevich, et al., 1999; Ruff
and Kanamori, 1983; Seno, 2005; Tichelaar and
Ruff, 1993]
Friday, November 23
No class.
Friday, November 30
Topic : ‘The Peru subduction zone’
Speakers : Aron
Additional references:
[Dorbath, et al., 1990; Gagnon, et al., 2005; Langer
and Spence, 1995; Pritchard, et al., 2007; Spence,
et al., 1999]
Friday, December 7
Topic : Debriefing of the seminar. Implications for current studies
Speaker: JPA
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