1. (Calo et al, GJI, 2011)

2. Reservoir-Induced Seismicity Victoria Stevens February 2012

3. References Talwani, P., 1997. On the nature of reservoir- induced seismicity, Pure and Applied Geophysics, 150, 473-492. Talwani, P., Chen, L. & Gahalaut, K., 2007. Seismogenic permeability, k(S), Journal of Geophysical Research-Solid Earth, 112. Gupta, H., 2002. A review of recent studies of triggered earthquakes by artificial water reservoirs with special emphasis on earthquakes in Koyna, Earth Science Reviews, 58, 279-310.

4. Plan of talk Introduction Observations Mechanisms Diffusivity and permeability

5. Introduction Noticed first when Lake Mead (on Arizona- Nevada border) was filled We know how and when conditions change so can study response Triggered by as little as 20 m filling – crust already close to failure M 6.3 triggered by reservoir filling in Koyna, India – killed 200 people.

6. Worldwide distribution of reservoir induced seismicity, all over M 4

7. Seismicity at Monticello Reservoir

8. Lake Mead

9. Koyna Seismicity from 1962 - present

10. India Earthquake Catalog 1960 to 1970 USGS NEIC PDE 2000 to 2012

11. Three time scales of seismicity Initial – Loading from water – increased pore pressure Delayed – Diffusion of pore pressure Protracted – Subsequent changes in water level

12. 1. Initial seismicity Effect of load

13. Initial seismicity

14. 2. Delayed seismicity

15. Coupled poroelastic response

16. Changes in elastic stress and pore pressure

17. 3. Protracted seismicity

19. Diffusivity and permeability Talwani et al. 2007 – Measured hydraulic diffusivity, C, from induced earthquakes – Found all fractures that produced seismicity had permeability of 5x10 -16 to 5x10 -14 m -2 – Called this the seismogenic permeability – Assumed seismicity depends on rate of increase of pore pressure, dp/dt.

20. Finding seismogenic values of C

21. Narrow range of k causes earthquakes

22. Hydraulic diffusivity

23. Permeability

24. THE END