2017 - 1 - 27 Testimony of David D. Jackson on Seismic Risks Related to Closure Date of Diablo Canyon

David Jackson, Ph.D. is serving as an expert witness for San Luis Obispo Mothers for Peace before the California Public Utilities Commission as it reviews PG&E's Joint Proposal for closure of the nuclear plant in 2024. Dr. Jackson makes the case for closure "at the earliest date that it is not absolutely necessary for electric power generation."


Prepared Direct Testimony of David D. Jackson, Department of Earth, Planetary, and Space Sciences, UCLA, for San Luis Obispo Mothers for Peace

Application 16-08-006 January 27, 2017

I. Retirement of the Diablo Canyon Nuclear Power Plant

Because of ongoing seismic risk to the Diablo Canyon Nuclear Power Plant (DCNPP), we contend that it should be retired at the earliest date that it is not absolutely necessary for electric power generation. We explain below that (1) substantial risk at DCNPP has been underestimated in official risk studies to date, and (2) those studies evaluated only a part of the risk which affects any decision of how long to continue operation of DCNPP.

Californians all face risk of financial loss, injury, and death from earthquakes. That risk is determined largely by the rate of earthquake occurrence and vulnerability to the ground shaking and permanent displacement caused by earthquakes. While we can’t control natural earthquakes, our only defense is to reduce vulnerability.

An important vulnerability to earthquakes is the electric power network, especially from nuclear power plants such as the Diablo Canyon Nuclear Power Plant (DCNPP). Potential seismic damage to the reactor core of DCNPP could cause significant loss of life and massive long-lasting environmental damage, as happened at the Fukushima Nuclear Power Plant from the 2011 Tohoku earthquake and tsunami. Probability of such damage at DCNPP has been the subject of extensive research mandated by the US Nuclear Regulatory Commission (NRC) and the US Environmental Protection Agency (EPA). While quantitative estimates are contentious, there is no question that catastrophic failure is not impossible. Beyond reactor core failure, nuclear power plants are subject to many other forms of seismic vulnerability including potential damage to other facilities and equipment, restricted access to the site, etc. Thus earthquake effects beyond those studied in detail could affect both the ability of DCNPP to provide power and the cost of operation over any specified period. Any decisions on the operating period of the plant must include consideration of those effects.

A. Estimated risk of earthquake damage at DCNPP

PG&E’s 2015 seismic hazards analysis consists primarily of two documents:

(a) Pacific Gas and Electric Co., Seismic Hazard and Screening Report, Diablo Canyon Power Plant Units 1 and 2 (“SHS Report”), submitted by letter from Barry S. Allen, PG&E to NRC, re: Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding the Seismic Aspects of Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident: Seismic Hazard and Screening Report (Mar. 11, 2015); and

(b) PG&E’s Seismic Source Characterization for the Diablo Canyon Power Plant, San Luis Obispo County, California; report on the results of a SSHAC level 3 study (Rev. A, March 2015) (“SSC Report”).

These documents, and supporting information referred to within, presented topographic, geological, geochemical, geophysical, and seismicity data used to estimate fault location; estimated locations and characteristics of known relevant faults; magnitudes and rates (i.e., probability per unit time) of earthquakes estimated to occur on those faults; locations and magnitudes of past earthquakes within range of DCNPP; information on rock and soil properties expected to affect seismic shaking at the plant from earthquakes elsewhere; quantitative estimates of the shaking, described by ground acceleration, as a function of frequency from each assumed potential earthquake; a comprehensive sum of the rate of ground shaking as a function of frequency for all assumed potential earthquakes; and finally an estimate of the highest level of acceleration, as a function of frequency, at which the reactor core would be acceptably safe. Every one of the items above is subject to uncertainties and assumptions.

Problems with the PG&E analysis in the 2015 SHS and SSC reports included the following:

  1. The analysis assumed that all major earthquakes occurred on known faults. In fact, many major earthquakes occur off of known faults, sometimes nearby (for example, the 2010 magnitude 7 El Mayor earthquake spanning the California/Mexico border) but sometimes many kilometers from any mapped fault (for example, the 2012 magnitude 8.6 earthquake west of Sumatra)

  2. The analysis assumed that major faults occur precisely on mapped faults, sometimes described with specific options for their geometry. This assumption is especially troubling for the recently discovered Shoreline fault, which is mapped to be just offshore 

    within a mile of the DCNPP site. Only one option was assumed for this fault, and the fault location was estimated from topographic sea-floor data and the locations of small earthquakes assumed to be on that fault. The topographic data provide only an indirect measure of fault location. The locations of the relevant small earthquakes was determined from a handful of seismometers on just one side of the fault, which can lead to a biased estimate. Uncertainties of the fault location from the small earthquake data allow the possibility that the Shoreline Fault actually lies directly beneath DCNPP.

    3. The analysis assumes that the largest earthquake on a mapped fault will be limited by the length of that fault. This assumption is frequently violated because many faults are not fully exposed at the surface, and as explained above many large earthquakes occur where no fault is mapped at all. The catastrophic 2011 magnitude 9 Tohoku-oki earthquake which devastated the Fukushima-Daichi power plant in Japan occurred where fault geometry suggested that earthquake magnitude would be limited to about 8.0.

    The result of these false assumptions is that the quantitative analysis of earthquake risk to the reactor cores may be substantially underestimated.

    B. Possible seismic effects beyond core damage

    The SHS and SSC reports dealt almost entirely with catastrophic core damage, but many other problems can be caused by earthquake activity. Structural, mechanical, hydraulic, and electrical systems required for safe and reliable operation may be damaged by earthquake shaking much more frequent than that required for reactor core failure. Such damage, or even the suspicion of such damage, could require interruption of the normal operation of the power plant. Non-structural damage has received serious attention in seismic vulnerability studies of all types of structures and facilities, in large part because of the pervasive damage throughout much of Japan caused by the Tohoku earthquake. Serious interruptions in service at DCNPP could result from seismic effects far from the power plant itself. Transmission, external power, communication, and transportation facilities are subject to interruptions that could then interrupt electric power production. Thus seismic effects far from the site itself contribute to operational risk, and such risks are much more frequent than those which could cause core failure.

    C. Conclusions

    Seismic risk to the reactor cores is substantial, and present models by PG&E likely underestimate it. Risks to other equipment, facilities, and personnel necessary for continued operation is much larger still. Neither the core risks nor the other risks have been considered in the Joint Proposal, which assumes continued operation till 2024 or 2025.

    The risks discussed above affect power generation only so long as DCNPP operates, so earlier shutdown in favor of alternate sources would be advantageous as soon as those alternate sources are available.

    II. Proposed Replacement Procurement

    No testimony at this time.

    III. Proposed Employee Retention and Severance Program

    No testimony at this time.

    IV. Proposed Community Impacts Mitigation Program

    No testimony at this time.

    V. Recovery of License Renewal Costs

    No testimony at this time.

    VI. Proposed Ratemaking and Cost Allocation Issues

    No testimony at this time.

    VII. Land Use, Facilities and Decommissioning Issues

    No testimony at this time.

    VIII. Additional Issues Not Addressed Above

    No testimony at this time.

    I declare that under penalty of perjury that the testimony submitted in this proceeding is true and correct to the best of my knowledge. The facts presented in this declaration are true and correct to the best of my knowledge, and the opinions expressed are based on my best professional judgment.

    Executed this 27th day of January 2017.

    (Electronically signed)

    David D. Jackson, Ph.D
    Dept. of Earth and Space Sciences UCLA
    Los Angeles, CA 90095-1567 Email: djackson@g.ucla.edu



    Department of Earth and Space Sciences, UCLA Los Angeles, CA 90095-1567
    January 27, 2017

    B.S., Department of Physics, California Institute of Technology,1965 Ph.D, Department of Earth and Planetary Science, MIT, 1969


    Professor of Geophysics, UCLA 1969 – 2011
    Distinguished Professor of Geophysics, Emeritus, UCLA 2011 - present

    Awards and Honors:

    •  National Academy of Sciences/Natural Research Council, Senior Resident Research Associateship, 1981- 1982

    •  Elected to Steering Committee, University NAVSTAR Consortium (UNAVCO) 1987, 1988, 1989, 1990, 1991, 1992.

    •  Elected Secretary, Seismology Section, American Geophysical Union, 1989.

    •  Elected President, Seismology Section, American Geophysical Union 1991.

    •  Fellow, American Geophysical Union 1993.

    •  Elected Chair, US National Committee for the International Union of Geodesy and Geophysics (IUGG).


    •  Elected Secretary, USNC/IUGG 2003-2007.

    •  Elected to Finance Committee, IUGG 2003-2007.

    •  Appointed Chair, Dept. Earth and Space Sciences, UCLA 2004-2007.

    •  Elected to Bureau of IUGG, 2007 – 2011.


      •  California Earthquake Prediction Evaluation Council, Office of Emergency Services, State of California 1984-2002.

      •  Committee on Seismology, National Academy of Sciences, National Research Council.

      •  Panel on Crustal Movement Measurements, Committee on Geology, National Academy of

        Sciences/National Research Council (NAS/NRC).

      •  Panel on Science of Earthquakes, NAS/NRC 1996-2003,

      •  Chair, Committee on Public Affairs, American Geophysical Union 1996-1998,

      •  Science Director, Southern California Earthquake Center 1996-1999.

      •  U. S. National Committee for IUGG 1995-2007.

      •  National Earthquake Prediction Evaluation Council, 2007 – 2014.

      •  Appointed Internation Association for Seismology and Physics of the Earth’s Interior (IAPEI) Liaison to

        Georisk Commission, 2007-2015

    • David D. Jackson, January 27, 2017 Published articles since 2010

      Kagan, Y. Y., and D. D. Jackson, (2016). Earthquake rate and magnitude distributions of great earthquakes for use in global forecasts, Geophys. J. Int., 206(1), 630-643, doi: 10.1093/gji/ggw161.

      Kagan, Y. Y. and Jackson, D. D., (2015). Likelihood analysis of earthquake focal mechanism distributions, Geophys. J. Int., 201(3), 1409-1415, DOI 10.1093/gji/ggv085

      Bird, P., Jackson, D.D., Kagan, Y.Y., Kreemer, C., and Stein, R.S.,GEAR1, (2015). A Global Earthquake

      Activity Rate Model Constructed from Geodetic Strain Rates and Smoothed Seismicity. Bulletin of the

      Seismological Society of America, October 1, 105:2538-2554

      Strader, A., & Jackson, D. D. (2015). Static Coulomb stress‐based Southern California earthquake

      forecasts: A pseudoprospective test. Journal of Geophysical Research: Solid Earth.

      Field, E. H., Biasi, G. P., Bird, P., Dawson, T. E., Felzer, K. R., Jackson, D. D., ... & Zeng, Y. (2015).

      Long‐Term Time‐Dependent Probabilities for the Third Uniform California Earthquake Rupture Forecast

      (UCERF3). Bulletin of the Seismological Society of America, 105(2A), 511-543.

      Field, E. H., Arrowsmith, R. J., Biasi, G. P., Bird, P., Dawson, T. E., Felzer, K. R., ... & Zeng, Y. (2014).

      Uniform California Earthquake Rupture Forecast, Version 3 (UCERF3)—The Time‐Independent

      Model. Bulletin of the Seismological Society of America, 104(3), 1122-1180.

      Rong, Y., Jackson, D. D., Magistrale, H., & Goldfinger, C. (2014). Magnitude limits of subduction zone

      earthquakes. Bulletin of the Seismological Society of America, 104(5), 2359-2377.

      Kagan, Y. Y., & Jackson, D. D. (2014). Statistical earthquake focal mechanism forecasts. Geophysical

      Journal International, ggu015.

      Strader, A., and Jackson, D. D. (2014). Near-prospective test of Coulomb stress triggering, J. Geophys.

      Res. Solid Earth, 119, 3064–3075, doi:10.1002/ 2013JB010780.

      Kagan, Y. Y., & Jackson, D. D. (2013). Tohoku earthquake: a surprise?. Bulletin of the Seismological

      Society of America, 103(2B), 1181-1194.

      Hiemer, S., Jackson, D. D., Wang, Q., Kagan, Y. Y., Woessner, J., Zechar, J. D., & Wiemer, S. (2013). A

      stochastic forecast of California earthquakes based on fault slip and smoothed seismicity. Bulletin of the

      Seismological Society of America, 103(2A), 799-810.

      Wang, Q., Schoenberg, F.P.,and Jackson, D. D. (2010). Standard Errors of Parameter Estimates in the , Bulletin of the Seismological Society of America 100 (5A)

      ETAS Model

      DOI: 10.1785/0120100001

      Kagan, Y. Y., & Jackson, D. D. (2012). Whole Earth high-resolution earthquake forecasts. Geophysical

      Journal International, 190(1), 677-686.

      Kagan, Y. Y., Jackson, D. D., & Geller, R. J. (2012). Characteristic earthquake model, 1884–2011,

      RIP. Seismological Research Letters, 83(6), 951-953.

      Chu, A., Schoenberg, F. P., Bird, P., Jackson, D. D., & Kagan, Y. Y. (2011). Comparison of ETAS

      parameter estimates across different global tectonic zones. Bulletin of the Seismological Society of

      America, 101(5), 2323-2339.

      Werner, M. J., Helmstetter, A., Jackson, D. D., & Kagan, Y. Y. (2011). High-resolution long-term and

      short-term earthquake forecasts for California. Bulletin of the Seismological Society of America, 101(4),


      Wang, Q., Jackson, D. D., & Kagan, Y. Y. (2011). California earthquake forecasts based on smoothed

      seismicity: Model choices. Bulletin of the Seismological Society of America, 101(3), 1422-1430.

      Jackson, D. D., & Kagan, Y. Y. (2011). Characteristic earthquakes and seismic gaps. Encyclopedia of

      Solid Earth Geophysics, 37-40.

      Kagan, Y. Y., & Jackson, D. D. (2011). Global earthquake forecasts. Geophysical Journal

      International, 184(2), 759-776.

      Wang, Q., Jackson, D. D., & Zhuang, J. (2010). Missing links in earthquake clustering

      models. Geophysical Research Letters, 37(21).

      Kagan, Y. Y., Bird, P., & Jackson, D. D. (2010). Earthquake patterns in diverse tectonic zones of the

      globe. Pure and applied geophysics, 167(6-7), 721-741.

      Schorlemmer, D., Zechar, J. D., Werner, M. J., Field, E. H., Jackson, D. D., Jordan, T. H., & RELM

      Working Group. (2010). First results of the regional earthquake likelihood models experiment. Pure and

      Applied Geophysics, 167(8-9), 859-876.

      Kagan, Y. Y., & Jackson, D. D. (2010). Earthquake forecasting in diverse tectonic zones of the