Operated by Los Alamos National Security, LLC for the U.S. …€¦ · Update PSHA Site characterization trenching Shaker Base Plate Geology mapping Seismic monitoring Modeling. Los

Operated by Los Alamos National Security, LLC for the U.S. Department of Energy's NNSA

Los Alamos National Laboratory

2016 Natural Hazard Phenomena conference: 10/19/2016 2

Los Alamos National Laboratory’s Seismic Hazard Characterization Program: a look

back and a path forward

Carene Larmat, Emily Schultz-Fellenz, Richard Lee, Michael Salmon, Lawrence Goen

Los Alamos National Laboratory2016 Natural Phenomena Hazard, Germantown, October 2016



LANL Seismic Hazards Program



Outline

• Where we are: • Seismic Hazard Program• Large uncertainty in the seismic hazard evaluation

• Seismic Hazard Evaluation Challenges for LANL:• Sitting on the foot-wall of a normal fault• Historically low seismicity rate• Complex environment and source-path • Unique challenge for site and topography effects.

• Activities of the Seismic Hazard Program• Overview• Trenching• Site and topography effects characterization



New Mexico Seismicity

SeismotectonicProvinces and Historical Seismicity, from 1869 to

present



LANL Seismic Design Basis Evolution• 1972 report by Dames and Moore (Investigation to support design of PF-4)

• Generic site/deterministic based

• Early 1990’s DOE requirements for Natural Phenomena Hazards• For sites with nuclear and high hazard facilities, site specific probabilistic hazard curves required• Otherwise rely upon national consensus standards

• 1995 PSHA:• Field investigations on site response and paleoseismic parameters

• Additional field work 1997-2002• Fault mapping, paleoseismic trenches Guaje Mountain, Pajarito Faults

• 2007 PSHA update (10-yr update)- Required because of new information, advancement in state-of-the-art:

• 2008-present Seismic Hazard Program Plan (rev 0)

• 2009 PSHA revision:- Modified for updated ground motion prediction equations- Refinement of vertical motion development

• 2009-present: monitoring and characterization programs

• 2018 Planned PSHA update (10-yr update)

Incr

easi

ng R

igor



Illustration of uncertainty obtained from the 2007 PSHA update

Slide 7

Seismic Hazard Curves for Peak Horizontal Acceleration, CMRR



Quaternary faults in the vicinity of LANL

Map of identified segments

Organization in a complex fault

system.



Logic Tree for the Pajarito Fault system



Comparison of Stochastic Attenuation Relationships for M 7.0 and Peak Ground Acceleration at CMRR

Illustration of the uncertainty in the medium ground motion



Ashen like soil layer amplifies seismic loads at the basement level.

Generalized Stratigraphy of Bandelier Tuff



How are we addressing these challenges:The Seismic Hazard Program Plan



Seismic Hazard Program Plan Objectives• To list and prioritize manageable work tasks that will reduce uncertainties in

our understanding of the seismic hazard at Los Alamos• Enable LANL to more cost effectively manage the associated NPH risk of LANL

operations• Improve integration of Earth science activities at LANL

Source models

Path (GMPEs)

Site characterization/Modeling

PSHA Methodology

PSHA Evaluation

Earthquake Monitoring

External review of PFS

Stochastic GMPE epistemic

P-wave nonlinear Simplified PSHA Revisit logic tree Network maintenance

RGR fault slip analysis

Vertical Seismic Profile Precariously perched objects

Revise PSHA Deploy vertical seismic array

Static stress model Support ER/EP seismic reflection survey

Extreme Sensitive motion upgrade

Mapping of SCC Additional Eqkes for kappa

Revise Method 3 Strong motion upgrade

Trenching SCC LANL velocity correlation model

Additional kappa assessment

Past, current and future activities



Activities focused on data collection

Data collection

Update PSHA

Site characterization

trenching

Shaker Base PlateShaker Base Plate

Geology mapping

Seismic monitoring

Modeling



Trenching



Trench Characterization, Documentation, and Field Interpretation

16

Geologic data indicates that seismic hazard is much greater than historic seismicity suggests. Seismic hazard is controlled by the Pajarito Fault System.



Geologic evidence for earthquake rates

The Pajarito Fault System has ruptured from 1 to 3 times in the last 10,000 years: Most recent events:

• Pajarito Fault: 1.5-2.5 ka; 6-10 ka*• Rendija Canyon Fault: >9 ka• Guaje Mountain Fault: 3-10 ka

*Could be interpreted as two events: 6-9ka and 9-11ka

Slide 17



Trench Sites & Timing

McCalpin(1999)

S a n t a F eN a t i o n a l F o r e s t

Wa t e r

EasternStrand

McCalpin(1999)Western

StrandMcCalpin (1999)

Trenches

Figu

re 4

Figu

re 3

Site 98-4

4

Site A

Site B

Site C

Site D

Site E

Site E-north(parkinglot site)

-1-106.35°-106.367°

35.8

5°35

.833

°

Phase 1 Sites

2016On LANL Lands:Site A

2017, Upon Receipt of PermitsOn SFNF Lands:Site BSite 98-4

On NPS Lands:Site E-north



Site characterization and modeling



Experiments: 2011, 2014• Use high-energy shear-wave source (T-Rex) to reduce uncertainty in

LANL site response• Key issues/questions

• Can novel techniques be used to understand/confirm high-strain properties of softer tuff units (Qbt3L) and lateral variability of shallow units

• Can Hoodoo(s) be used to constrain design ground motion• Can a surface vibratory source be used to characterize deeper crustal

reflectors or generate refracted P- and SH-waves

Shaker Base PlateShaker Base Plate



Observa( ons+for+sta( on+#5+ Modeling+for+sta( on+#5+

peaks&at&1.53Hz,&1.56Hz&and&1.88Hz& peaks&at&1.3Hz,&1.15Hz,&and&0.9Hz&

Topography and site effects from ambient noise

From Stolte, Cox, Stokoe and Lee (submitted)



3D numerical modeling

Basin Materials Geologic Groups and Associated Members

Elastic Properties and Associated Material Units

Vp (m/sec) Vs (m/sec)

QBT

Bandelier Group (Qb) Tshirege Members (Qbt) Cerro Toledo Interval (Qct) Otowi Members (Qbo)

Qbt* Qct, Qbo*

528 1558

Qbt3,4 Qbt2, Qbt1*, Qc*,Qb*

305 900

TB4 Flow body in Puye Cerros del Rio Basalts (Tb4)

Tb4 2288 Tb4 1321

TPF

Puye Fanglomerate (Tpf) Pumaceous (Tpp) Tschicoma (Tt)

Tp*, Tt* 2288 Tp*, Tt* 1321

TPT Gravel Puye Totavi (Tpt)

Tpt 2288 Tpt 1321

TK Flow body in Santa Fe Keres Basalt (Tk)

Tk 2797 Tk 1615

TF Santa Fe Group Fanglomerate (Tf)

Tf 2797 Tf 1615

TSF Santa Fe Silt and Sands Tertiary (Ts) Galisteo (Tgs)

Ts, Tgs 2797 Ts, Tgs 1615

PAL Older Sedimentary Pal 2797 Pal 1615

PcF Pre Cambrian Flow Pc Flow 5993 Pc Flow 3460 Pc Pre Cambrian Pc 5993 Pc 3460

Based on the Spectral Element Method:• Finite element – hexahedra• Spectral convergence• Full wave 3D modeling (Chaljub, GJI, 2015)



Preliminary results Site Effects

Predicted resonance peak:f0=vs/4H=2.24Hz

Operated by Los Alamos National Security, LLC for the U.S. Department of Energy's NNSA

Questions?



LANL Strategy Seismic Safety (summary)

• Seismic Hazard Program – Follow accepted guidance for seismic characterization, model development, incorporation of uncertainties, peer review, and documentation

• Engineering Standards Program – Manual for compliance with standards and orders

• Engineering Evaluation – Design new facilities to mitigate the effects of seismic hazard, evaluate existing facilities to understand impact of the seismic hazard

Seismic Hazard

Program

Engineering Evaluations

Engineering Standards Program



Magnitude and Distance Contributions to the Mean

Peak Horizontal Acceleration Hazard at

10,000-Year Return Period at CMRR (Stochastic).

Operated by Los Alamos National Security, LLC for the U.S. …€¦ · Update PSHA Site characterization trenching Shaker Base Plate Geology mapping Seismic monitoring Modeling. Los

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