1. Schuyler Ozbick

2. http://www.eqecat.com/catwatch/virginias-m-5-8- wake-up-call-2011-09-07/

3.  Triggered earthquakes can be seen at distances larger than a regional fault network  They can also occur anytime between seconds and decades after the initial earthquake in the sequence

4. Coulomb failure criterion Coulomb stress = shear stress – friction coef. (normal stress-pore fluid P) Fault brought closer to rupturing if shear stress is increased or the effective normal stress is decreased.

5. Changes in Coulomb stress for a vertical strike-slip fault where green represents no change in stress

6.  1933 Long Beach. M= 6.4  1952 Kern Country California. M= 7.3  1971 San Fernando. M= 6.7  1994 Northridge. M= 6.7 http://content.cdlib.org/ark:/13030/kt8p3014k2/

7.  1933 Long Beach. M= 6.4  1952 Kern Country California. M= 7.3  1971 San Fernando. M= 6.7  1994 Northridge. M= 6.7 http://www.ngdc.noaa.gov/hazardimages/picture/sho w/109

8.  1933 Long Beach. M= 6.4  1952 Kern Country California. M= 7.3  1971 San Fernando. M= 6.7  1994 Northridge. M= 6.7 http://earthquake.usgs.gov/earthquakes/states/events/1971_02_09_photos.php

9.  1933 Long Beach. M= 6.4  1952 Kern Country California. M= 7.3  1971 San Fernando. M= 6.7  1994 Northridge. M= 6.7 http://www.flickriver.com/places/United+States/California/Los+Angeles/Northridge/search/

10.  July 6, 1954 at south end of Rainbow Mountain fault  August 24, 1954 along Rainbow Mountain fault  December 16, 1954 at Fairview peak  December 16, 1954 at Dixie Valley ◦ (4 min 30 sec later)  March 29, 1959 south end of Dixie Valley fault  June 23, 1959 in SW Fairview Peak region

11. bssa.geoscienceworld.org

12.  April 1992 Joshua Tree quake of M=6.1  June 1992 Landers quake of M=7.3  The Landers quake caused increased seismic activity in ranges from a few meters to beyond 1000 km and triggered many small (M=1-3) events

13.  Joshua Tree and Landers earthquakes created a new positive Coulomb stress change pattern  The Big Bear earthquake was triggered 3.5 hours after Lander quake.  Big Bear earthquake M=6.3

14.  After the Big Bear quake, the Coulomb stresses were altered. Before Big Bear After Big Bear

15.  April 1992 Joshua Tree quake of M=6.1  June 1992 Landers quake of M=7.3  June 1992 Big Bear quake of M=6.3 ◦ 3.5 hours after Landers  October 1999 Hector Mine quake of M=7.1

16.  Does this earthquake belong to a sequence?  Was it triggered by a previous earthquake?  What does the time delay suggest? ◦ Redistributed stress postseismatically by relaxation, rebound and afterslip?  Does it conform to an increased Coulomb stress? ◦ Disagreements over stress shadows

17. Coulomb stress and observed aftershocks of Homestead Valley earthquake of 1979 M=5.5

18.  Earthquake triggering by static, dynamic, and postseismic stress transfer, Andrew M. Freed, Annu. Rev. Earth Planet. Sci. 2005 33:335-67  Earthquake processes in the Rainbow Mountain-Fairview Peak-Dixie Valley, Nevada, region 1954-1959, Diane I. Doser, Journal of Geophysical Research, vol 91 no. B12 pg. 572-586, Nov 1986  Delayed triggering of 1999 Hector Mine Earthquake by viscoelestic stress transfer, Andrew M. Freed and Jian Lin, Nature vol 411 pg 180-181, May 2001