Updating Models of Earthquake Recurrence
and Rupture Geometry of the Cascadia
Subduction Zone
for UCERF3 and the National Seismic Hazard
Maps
Art Frankel
U.S. Geological Survey
Seattle
presentation for UCERF3 SRP meeting
Nov. 11-12, 2010
Cascadia Subduction Zone Interface Earthquakes
Major Issues for UCERF3 and NSHM
• What is the magnitude-frequency distribution? (rate
of M9’s that rupture entire CSZ; rates of M8’s that
rupture part of CSZ)
• Does southern CSZ produce more M8’s than
northern portion?
• Is the CSZ segmented along strike?
• Can some of the “M9” quakes be series of M8s over
< 20 years or so?
• Where is the eastern edge of the locked zone?
geometry of CSZ
PacNW Plans for UCERF 3 and next update of
National Seismic Hazard Maps
• Focused meeting on turbidite evidence for CSZ great
earthquakes, Nov 18-19 in Corvallis; evaluate 230 yr
recurrence for M8’s on southern CSZ from turbidite and
compare dates from turbidites to onshore data; compare
turbidite and onshore data in northern CSZ; discuss M8
cluster possibility; discuss possible segmentation; magfreq distributions
• Pacific Northwest regional workshop Fall 2011 (eastern
edge of CSZ, source models, faults, attenuation relations);
possible separate workshop on eastern edge of locked
portion of CSZ
From 2008 NSHM Documentation
Two Sets of Scenarios for CSZ revised for 2008
Update
• M8.8-9.2 rupturing entire CSZ; 500 year average
recurrence time from paleoevent dates
(probability of 0.67)
• M8.0-M8.7 floating rupture zones; rupture under
any location along coast with rate of 1/500, on
average (probability of 0.33)
equal probabilities assigned to 8.3, 8.4, 8.5, 8.6,
8.7 scenarios; 8.0,8.1,8.2 assigned half probability
of others
From 2008 NSHM Documentation
From Goldfinger et al. (in press); results from turbidites
This will be evaluated in Nov 18-19 meeting
From Goldfinger et al. (in press)
From Goldfinger et al. (in press)
Compilation of on land
paleoseismic data
From Nelson et al. (2006)
Figure from Goldfinger et al. (in press)
Where is the eastern edge of the
locked zone?
• Thermal models
• Global analogs
• GPS data (e.g., McCaffrey; Chapman and
Melbourne)
• Uplift data (e.g., Burgette, Weldon et al.,
2009); historic and from paleoseismic
• Updip limit of ETS
From Chapman and Melbourne (2009): ETS and Locked Zone
0.2 wt
0.2 wt
0.1 wt
0.5 wt
Nonvolcanic tremor locations
From Aaron Wech, UW
Figure from Liu et al (2010)
For Nankai Trough
Comparing locked zone
derived from GPS with
location of LFE’s
• Develop new magnitude-frequency distribution(s) for CSZ;
possibly varying along CSZ
• Assess possibility that some “M9” quakes are series of M8s
over < 20 years or so
• Evaluate possibility of temporal clustering of whole rupture
CSZ proposed by Goldfinger et al. (in press)
• Revisit time-dependent model for CSZ. Do we include
southern CSZ ruptures with short return times?
• Update location of plate interface using compilation of
McCrory and other work
• PacNW workshop to discuss CSZ recurrence and geometry,
crustal faults, atten relations (possible separate workshop
on geometry of CSZ)
Possible configurations for rupture zone of great Cascadia Earthquakes
From Fluck et al. (1997)
From Goldfinger et al. (in press)
From Brian Atwater (2010)