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SCEC Cajon Pass Earthquake Gate Area: Progress and Future Plans

Applications Due: July 31, 2020
Participants: 100 maximum
Date: September 4, 2020
(9:00am-3:30pm Pacific Time)
SCEC Award: 20056

Conveners: Nate Onderdonk, Julian Lozos, and Craig Nicholson

SUMMARY: SCEC defines Earthquake Gate Areas (EGA) as “regions of fault complexity conjectured to inhibit propagating ruptures, owing to dynamic conditions setup by proximal fault geometry and material properties, distributed deformation, and earthquake history." The four primary science questions related to EGAs are:

  1. How do fault intersections affect the probability of through-going earthquake ruptures?
  2. How does 3D fault geometry and stress variations modulate these through-going rupture probabilities?
  3. How do prior ruptures affect future rupture paths and probabilities?
  4. Does the current stress field reflect recent rupture history or is it more influenced by other factors?

The purpose of this workshop is to present and discuss ongoing research in the Cajon Pass area, to solicit and encourage additional studies and new investigators, and to establish science priorities for the remainder of SCEC5 and beyond. 2020 is the beginning of the fourth year of SCEC5 and the Cajon Pass Earthquake Gate initiative. Numerous projects have been funded to address the Cajon EGA science plan. This workshop will bring Cajon Pass investigators together to assess what progress made since the first Cajon Pass workshop in 2018, and what still remains to be done.

Due to the ongoing COVID-19 pandemic, this workshop will be held as a web conference on September 4, 2020. The program will consist of four sessions that include invited talks and lightning presentations by workshop participants. We encourage anyone currently working on, or interested in the questions outlined above to apply. We welcome expertise in earthquake geology, geophysics, modeling, and the Cajon Pass region. Participants will be selected based on the level and relevance of their research interests in Cajon Pass and the Cajon Pass EGA Initiative. The workshop is limited to 100 participants.

All times listed in the agenda below are Pacific Time Zone.

08:45 - 09:00 Workshop introduction and Cajon Pass EGA background Julian Lozos
09:00 - 09:30 Session 1: Updates from field geology and remote sensing Moderator: Julian Lozos
09:00 - 09:15 A maximum rupture model for the Southern San Andreas and San Jacinto Faults, California, derived from paleoseismic earthquake ages: observations and limitations Kate Scharer
09:15 - 09:30 Cucamonga Fault slip rates in space and time Devin McPhillips
09:30 - 09:45 The power of passenger faults as passive recorders: refining the timing and mechanics of San Andreas-San Jacinto joint rupture through Cajon Pass Alba Rodriguez Padilla
09:45 - 10:00 Tectonic-geomorphic mapping along the northernmost San Jacinto fault zone and implications for slip distribution Drake Kerr
10:00 - 10:15 Geomorphic mapping and trench exposures suggest the Glen Helen fault has not experienced surface rupture in the past 2000 years or more Nate Onderdonk
10:15 - 10:30 Discussion All
10:30 - 11:00 Break  
11:00 - 12:30 Session 2: Geophysics and insights from other Earthquake Gates Moderator: Nate Onderdonk
11:00 - 11:15 3D Fault Geometry and Coupling at the Junction of the San Andreas and San Jacinto Fault Systems, Cajon Pass Craig Nicholson
11:15 - 11:30 San Gregorio-San Andreas Fault branch analog Gordon Seitz
11:30 - 11:45 Measuring distributed strain from past surface ruptures, with the aim to develop probabilistic hazard models of distributed ruptures Chris Milliner
11:45 - 12:00 Reconciling geologic observations and numerical models of an earthquake gate along the Altyn Tagh fault, northwest China Veronica Prush
12:00 - 12:15 Complex strike-slip fault systems in Chile, what we know and what we know we don't know Greg De Pascale
12:15 - 12:30 Discussion All
12:30 - 13:00 Break  
13:00 - 14:30 Session 3: Updates from modeling studies Moderator: Craig Nicholson
13:00 - 13:15 Using the focal mechanisms within the San Bernardino Basin to infer creep below 10 km along the San Jacinto fault Michele Cooke
13:15 - 13:30 The effect of Asymmetric Topography on Rupture Propagation Across the Cajon Pass Christos Kyriakopoulos
13:30 - 13:45 Multicycle dynamics of the southern San Andreas Fault and San Jacinto fault: the effect of the Cajon Pass and the Big Bend earthquake gates Dunyu Liu
13:45 - 14:00 Stress state in the Cajon Pass Earthquake Gate area Karen Luttrell
14:00 - 14:15 Variations of stress parameters around the South Central Transverse Ranges Niloufar Abolfathian
14:15 - 14:30 Discussion All
14:30 - 15:00 Summary Discussion: Workshop Recommendations and Future Plans All
15:00 Adjourn  


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