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Recent News & Publications

Published on June 22, 2017

LCI engineering geologists support California Department of Water Resources Oroville Dam Emergency Recovery Spillways Project. More pictures about this project are available at California Department of Water Resources FaceBook Page.

Published on June 22, 2017

Lettis Consultants International, Inc. is part of the geologic and seismic hazard team working on the Clinch River Nuclear Site near Oak Ridge, Tennessee. The project recently submitted an Early Site Permit (ESP) application with the Nuclear Regulatory Commission with the intent of installing a Small Modular Nuclear Power Station and is discussed in this article. Seismic source characterization included evaluation of the Eastern Tennessee Seismic Zone that was modeled as part of the Probabilistic Seismic Hazard Analysis (PSHA). Key LCI staff include Matt Huebner, Gabriel Toro, Ivan Wong, and Kevin Clahan.

Published on June 10, 2017

12 December 2016 – William R. Lettis has been selected as the William B. Joyner Memorial Lecturer for 2017. Lettis founded William Lettis & Associates, Inc. in 1990 and Lettis Consultants International, Inc. in 2011 to provide consultancy at the interface of earthquake science and earthquake engineering. He will deliver his lecture in April 2017 at the Seismological Society of America (SSA) Annual Meeting in Denver, Colorado and in March 2017 at the Earthquake Engineering Research Institute (EERI) Annual Meeting in Portland, Oregon.

Lettis has characterized seismic sources for probabilistic seismic hazard analyses for high-risk facilities at over 100 locations within the United States and throughout the world, in a range of seismic environments. His paleoseismic research on active faults has resulted in more than 100 publications and in guidance documents for the Nuclear Regulatory Commission and the International Atomic Energy Agency.

Published on June 9, 2017

Chris Kemp of LCI has authored a technical paper titled “LiDAR Based Fault Mapping in Southern Owens Valley, California.” Chris’s co-authors are Scott Lindvall, also of LCI, Christopher Heron of Los Angeles Department of Water and Power, and Christopher Goetz of AECOM.

High-resolution LiDAR topographic data were evaluated for evidence of surface faulting to support a surface fault rupture hazard assessment of the Los Angeles Department of Water and Power’s existing North Haiwee Dam and proposed North Haiwee Dam 2 in southern Owens Valley, Inyo County, CA. New mapping was performed over a 70 mi2 (180 km2) area covered by the project and publicly available 3-ft-resolution (0.9 m) LiDAR data. This new mapping revealed no surface faults that extend into the existing dam or that traverse the footprint of the proposed dam. However, detailed mapping identified a number of new faults that together define fine-scale faulting comprising the northern ends of interpreted regional-scale slip transfer systems in the southern Walker Lane.

Published on June 9, 2017

Chris Kemp and Scott Lindvall of LCI are co-authors on a technical paper titled “Fault Rupture Hazard Assessment for North Haiwee Dam No. 2, Owens Valley, California” with lead author Christopher Goetz of AECOM. Christopher Heron and Kevin Mass of Los Angeles Department of Water and Power, and Mark Olson of Advanced Geoscience are also co-authors on this paper.

A comprehensive investigation of local faulting was done to provide a deterministic assessment of the potential for surface fault rupture under or adjacent to the planned North Haiwee Dam 2. Preliminary fault trenching investigations discovered a previously unknown, N-NW striking fault that cuts latest Pleistocene alluvium along the east bank of Haiwee Reservoir approximately 2000 feet south of the existing dam. Final fault investigations consisting of geologic/geomorphic mapping, lidar based fault mapping, fault trenching, sonic drilling, cone penetrometer testing (CPT), seismic reflection surveys, and age dating (radiocarbon, OSL and cosmogenic) were done to assess whether Fault A or any other faults represent a surface fault rupture hazard to NHD2. These investigations demonstrated that Fault A is no closer than ~900 feet east of the dam footprint and suggest that the alluvial and bedrock stratigraphy underlying the proposed dam footprint is continuous and unbroken by faulting.

Published on March 22, 2017

Matthew Huebner of LCI has authored a technical paper entitled, “Confirmation of the southwest continuation of the Cat Square terrane, southern Appalachian Inner Piedmont, with implications for middle Paleozoic collisional orogenesis”. Matthew’s co-authors are Robert D. Hatcher Jr. and Arthur J. Merschat.

Detailed geologic mapping, U-Pb zircon geochronology and whole-rock geochemical analyses were conducted to test the hypothesis that the southwestern extent of the Cat Square terrane, southern Appalachians, continues from the northern Inner Piedmont (western Carolinas) into central Georgia. Geologic mapping revealed the Jackson Lake fault, a ~15 m-thick, steeply dipping sillimanite-grade fault zone that truncates lithologically distinct granitoids and metasedimentary units, and roughly corresponds with a prominent aeromagnetic lineament hypothesized to represent the southern continuation of the terrane-bounding Brindle Creek fault. Based primarily on a distinct partitioning of granitoid ages and lithologic distinctions similar to the northern Inner Piedmont, the rocks southeast of the Jackson Lake fault are interpreted to represent the southwestern extension of the Cat Square terrane. Data suggest Cat Square terrane metasedimentary rocks were initially deposited in a remnant ocean basin setting, and developed into an accretionary prism in front of the approaching peri-Gondwanan Carolina superterrane, ultimately overridden by it in the Devonian to Early Mississippian Acadian/Neoacadian orogeny. Burial to >20 km resulted in migmatization of lower plate rocks, forming an infrastructure beneath the Carolina superterrane suprastructure. Provenance patterns support ~250 km of Devonian dextral translation of the composite Inner Piedmont relative to Laurentia. The megascopic thrust-nappe structural style of the northern Inner Piedmont, combined with southwest-directed lateral extrusion at mid-crustal depths, is suggested to reconcile differences in timing of metamorphism between the Carolina and central Georgia Inner Piedmont and structural contrasts between the Brindle Creek and Jackson Lake faults. A copy of publication is available at American Journal of Science.

Published on January 25, 2017

Andy Seifried of LCI has co-authored a technical paper titled, “Spectral Variability and Its Relationship to Structural Response Estimated from Scaled and Spectrum-Matched Ground Motions” with Jack Baker of Stanford University.

Conditional spectral dispersion (CSD) is a measure of response spectrum variability that implicitly characterizes the variety of spectral shapes within a suite of ground motions. It is used here to explain the discrepancy between median structural demands estimated from different suites of scaled and spectrum-matched ground motions. Performing response history analyses with spectrum-matched ground motions is known to result in unconservatively biased median demand estimates in some cases. Herein, several suites of scaled ground motions with equivalent median intensities and varying levels of CSD are selected. A single suite of spectrum-matched ground motions is also created. These records are used to analyze the responses of inelastic single-degree-of-freedom and first-mode-dominated multiple-degree-of-freedom structural systems. Collapse capacities are also examined. A consistent trend between CSD and resulting median responses indicates that the bias phenomenon can be fully explained by an asymmetric relationship between conditional spectral ordinates at periods affecting inelastic response. A copy of publication is available at Earthquake Spectra website.

Published on July 27, 2016

BSSA June 2016 Cover

Arash Zandieh of LCI has authored a technical paper entitled, “Estimation of κ0 Implied by the HighFrequency Shape of the NGAWest2 GroundMotion Prediction Equations”. Arash’s co-authors are Ken Campbell and Shahram Pezeshk at CoreLogic, Inc. and The University of Memphis, respectively.

Authors used the inverse random vibration theory approach to calculate Fourier amplitude spectra from predicted values of response‐spectral acceleration for all five Next Generation Attenuation (NGA)‐West2 ground‐motion prediction equations (GMPEs). Authors used these spectra to estimate κ0 using the spectral‐decay method. Each GMPE was evaluated for a National Earthquake Hazard Reduction Program B/C site condition and for default estimates of depth to the top of rupture, hypocentral depth, and sediment (basin) depth. Authors derived estimates of κ0 for magnitudes ranging from 3.5 to 8.0 and distances ranging from 5 to 20 km and used a mixed‐effects model to derive equations for these estimates as a function of magnitude. The values of κ0 obtained in this study are intended to represent the high‐frequency shape of the median predicted spectral accelerations from the GMPEs. The κ0 model developed in this study can be used in inversions to develop stochastic models that are intended to mimic the predictions from the NGA‐West2 GMPEs. A copy of publication is available at BSSA wesbite.

Published on May 31, 2016

WCEE_2017LCI Employees to present 4 papers at World Conference on Earthquake Engineering. LCI employees Robin McGuire and Ivan Wong will attend and present 4 technical papers at the 16th World Conference on Earthquake Engineering, to be held in Santiago, Chile on January 10—13, 2017.  These papers address earthquake hazard issues relevant to LCI’s clients worldwide, and are entitled:

– Analysis of Magnitude-Spatial Trends of Induced Seismicity in Oklahoma, USA (McGuire et al.)
– Time-Dependent Seismic Hazard above the South America Subduction Zone in Central and Southern Chile (Wong et al.)
– Assessing the Seismic Hazard in Northwestern Peru (Wong et al.)
– Assessing the Damage Potential of Injection-Induced Earthquakes in the U.S. (Wong et al.)

These papers build upon the experience and data that LCI employees have gained in working on seismic hazard projects throughout the world, and LCI is pleased to share these interpretations and insights with others by publication of these papers in the conference proceedings.  This conference, held every 4 years, is being conducted under the auspices of the International Association of Earthquake Engineering.  The IAEE was organized at the first World Conference on Earthquake Engineering held in San Francisco in 1956 to promote the understanding of earthquake hazards and reduction of earthquake risk worldwide.

Published on April 4, 2016

Ivan Wong

LCI is pleased to announce that Mr. Ivan Wong has joined our team as a Principal Seismologist. Ivan is a nationally and internationally recognized expert in seismic hazard and seismic risk evaluations, with more than 40 years of experience in the fields of seismology and seismic geology with an emphasis on studies in seismicity, seismotectonics, and earthquake ground motions. His professional experience includes work on more than 200 dams in the U.S., Canada, Thailand, Eritrea, and Egypt; bridges, tunnels and pipelines; mining facilities and tailings dams in the western U.S., Peru, Colombia, Ecuador, and Chile; nuclear power plants and waste repositories; cogeneration plants; and LNG facilities and offshore petroleum platforms. Ivan’s recent work includes studies of earthquakes in the central United States and Canada triggered by deep wastewater injection and hydraulic fracturing. He has worked extensively for FEMA particularly in the implementation of the loss estimation software HAZUS. Ivan has served on numerous professional committees and panels, particularly for the U.S. Geological Survey, and is actively involved in the Earthquake Engineering Research Institute and the Seismological Society of America. He has authored or co-authored more than 300 publications including more than 130 papers (26 in peer-reviewed journals), and more than 190 abstracts published in professional journals and conference proceedings. Ivan’s expertise in seismology and seismic hazard analysis complements LCI’s strengths in seismic geology and neotectonics, and we are proud and excited to have him on our team.

Published on October 8, 2015

GEER ReportKevin Clahan of LCI participated on the recent Geotechnical Extreme Event Response (GEER) team to the Gorkha Earthquake in Nepal. LCI’s internal research funding program provided the means for Mr. Clahan to join the GEER team as funding for such response is limited. The GEER Association assembled a reconnaissance team to evaluate geotechnical impacts of the April 25, 2015 Gorkha Earthquake and its related aftershocks. Mr. Clahan arrived in Nepal shortly after the Mw7.8 mainshock and was doing reconnaissance when the largest aftershock (Mw 7.3) occurred on May 12, 2015. The focus of the reconnaissance was on time-sensitive (perishable) data, and the GEER team included a large group of experts in the areas of Geology, Engineering Geology, Seismology, Tectonics, Geotechnical Engineering, Geotechnical Earthquake Engineering, and Civil and Environmental Engineering. The GEER team worked in close collaboration with local and international organizations to document earthquake damage and identify targets for detailed follow up investigations. A summary report of the Gorkha earthquake published by GEER is available through the following link, a technical paper published at Seismological Research Letters is available through the following link.

Published on February 9, 2015

Link to NEHERPAndrew Seifried and Gabriel Toro of LCI were awarded a USGS research grant to study the calculation of site effects of strong ground motion.  Each year the USGS Earthquake Hazards Program, which is a part of the National Earthquake Hazards Reduction Program, awards research grants to universities, geological surveys, and private institutions aimed at evolving earthquake science and ultimately reducing earthquake losses.  Dr. Seifried and Dr. Toro’s project, “Improved estimation of site response using random vibration theory”, will introduce and evaluate an alternative approach to random vibration theory (RVT)-based site response analysis.  The goal of this work is to reduce the unnecessary conservatism introduced by some other approaches in common use, while maintaining the computational efficiency that makes RVT advantageous in a site-specific or regional probabilistic seismic hazard analysis framework.  Stay tuned for presentation of this research as it progresses!

Published on February 2, 2015

Seal of University of California BerkeleyRobin McGuire has co-authored a technical paper entitled, “Evaluation of Ground Motion Selection and Modification Procedures using Synthetic Ground Motions,” which examines methods of scaling and modifying earthquake ground motion records to represent design motions for structures.  Robin’s co-authors are Neal Simon and Anil Chopra, both at Cal Berkeley.  The current paper expands on a 2014 paper, “A framework for the evaluation of ground motion selection and modification procedures,” written by the same authors, that was published in Earthquake Engineering and Structural Dynamics in October, 2014.

The latest paper uses 10,000 synthetic ground motions to evaluate alternative procedures to scale and modify ground motions, incorporating concepts of conditional intensity measures.  The research illustrates how we can quantify and improve the precision of seismic hazard estimates and seismic demand curves (which quantify risk to structures based on the response of nonlinear structural models).  These results will help engineers select and scale real recorded ground motions to represent intense levels of shaking, which perhaps have not been well documented for a particular site (with a particular magnitude and distance dominating the seismic risk).  The current paper has been accepted for publication later this year in the journal Earthquake Engineering and Structural Dynamics.  Robin’s participation in this research was supported by LCI’s continued commitment to ongoing studies in earthquake engineering and geosciences related to better understanding and reducing earthquake risk to society.

Published on December 9, 2014

Link to article
Lettis Consultants International (LCI) is helping the mountain top city of Aizawl, the capital of northeast India’s Mizoram state, understand its seismic and landslide hazard risk.  With funding from GeoHazards International and global reinsurer Munich Re, LCI Principal Engineering Geologist Kevin Clahan participated on a panel of local and international experts to assess the hazards associated with earthquakes and landsliding on the high risk community of Aizawl, India.  The resulting report “A Safer Tomorrow? Effects of a Magnitude 7 Earthquake on Aizawl, Mizoram and Recommendations to Reduce Losses” is available through the following link. In addition to helping produce the Aizawl Seismic Scenario Report, LCI Principal Geologist Kevin Clahan helped launch the Landslide Policy Committee for Aizawl City, with municipal, state, and technical participants; helped the Committee create a landslide safety action plan; helped Aizawl Municipal Council write new site development regulations to control modifications that can destabilize slopes; and developed detailed landslide hazard maps and a landslide inventory, to form the basis of the city’s new land use policies and regulations.  A summary of the project results was published in the December issue of The Leading Edge, the Society for Exploration Geophysicists’ magazine.

Published on September 9, 2014

Seal of University of California BerkeleyDr. Robin McGuire elected to the University of California, Berkeley, Academy of Distinguished Alumni, Class of 2014. For his career-long contributions to seismic hazard and risk analysis, seismic design concepts, and earthquake engineering, LCI’s Dr. Robin McGuire was elected to the University of California, Berkeley, Academy of Distinguished Alumni, Class of 2014. Dr. McGuire, who earned an M.S. degree in structural engineering from the Civil and Environmental Engineering Department at U.C. Berkeley, will be inducted into the Academy at a banquet and ceremony to be held in Berkeley in October. Through his research and work with clients and professional organizations, he has contributed to the knowledge, methodology and implementation of seismic hazard and risk concepts in both analysis and design for large scale facilities and small projects. We at LCI congratulate Robin on this honor and look forward to collaborating with him on many projects to come. An announcement by UC Berkeley of his induction into the Academy is available at

Published on July 19, 2013

Induced Seismicity Potential in Energy Technologies identifies gaps in knowledge and research needed to advance the understanding of induced seismicity; identify gaps in induced seismic hazard assessment methodologies and the research to close those gaps; and assess options for steps toward best practices with regard to energy development and induced seismicity potential. LCI’s Robin McGuire was a member of the Panel on Induced Seismicity Potential in Energy Technologies, which was conducted by the National Research Council (the research arm of the National Academy of Engineering and National Academy of Sciences). The study examined induced seismicity caused by human activities related to energy technologies. The Panel’s meetings were held in 2011-2012, a prepublication report was issued in June, 2012, and the final report was published by the National Research Council in 2013. The report can be viewed at the following site:

Robin McGuire helped the National Research Council prepare a video giving an overview of the report and illustrating ways in which energy technologies induce earthquakes.

Published on August 1, 2013

Through funding from the National Earthquake Hazards Reduction Program of the United States Geological Survey, LCI is performing paleoseismic and seismic hazard research in the San Francisco Bay area on the northern segment of the Hayward fault (Williams and Baldwin, 2013) and southern Rodgers Creek fault (Givler and Baldwin, 2013), as well as in the central United States (Baldwin and Gray, 2013) on the Big Creek fault in Arkansas. Most recently, previous work by LCI staff on the Green Valley fault, located in the eastern San Francisco Bay area, was published in Bulletin of Seismological Society of America.  This research was performed in collaboration with the U.S. Geological Survey. Some of the other links include the following: Givler and Baldwin USGS website link Williams and Baldwin: USGS website link