Ivan G. Wong

• Master of Science
• Senior Principal Seismologist at Lettis Consultants International

We have performed site-specific probabilistic seismic hazard analyses (PSHA) and site response analyses (SRA) for five demonstration sites located in South Africa and Zimbabwe. Outside of the East African Rift, much of southern Africa is considered a tectonically stable continental region with few recognized Quaternary active faults; however, the r...

The recent increased need for site-specific probabilistic seismic hazard analyses (PSHAs) of tailings storage facilities (TSFs) has been driven by recent failures worldwide that resulted in significant loss of life, injuries, and environmental damage. As a consequence, the Global Industry Standard on Tailings Management was developed setting guidel...

The selection of ground motion models (GMMs) introduces a significant source of uncertainty in probabilistic seismic hazard analysis (PSHA). As part of site-specific PSHAs for five demonstration sites located in South Africa and Zimbabwe, we have evaluated the applicability of existing GMMs for southern Africa by comparing instrumental ground-motio...

Synchronous rupture involving two or more antithetic or synthetic faults results in higher levels of ground shaking hazard compared to that computed separately for each fault. We describe methodologies to estimate the ground motions both deterministically and probabilistically using a square-root-sum-of-the-squares approach and provide a case study...

This report documents the assessment by the U.S. Geological Survey (USGS) Earthquake Rupture Forecast (ERF) Review Panel of the draft ERF for the conterminous United States (CONUS-ERF23) proposed for the 2023 update of the National Seismic Hazard Model (NSHM23). Panel members participated with the ERF Development Team in several verification and va...

As part of the development of Induced Seismicity Mitigation Plans (ISMPs) for four proposed enhanced geothermal system sites in Nevada and Oregon, we are evaluating the potential for induced and triggered seismicity and the associated seismic hazard and risk at each site in line with the seven steps described in the U.S. Department of Energy's (DOE...

In this study, the number of periods in acceleration response spectra and the characteristics of input motion and screening criteria on the representative earthquake time histories are investigated for the Charleston, SC, area. Uniform hazard spectra (UHS) obtained from probabilistic seismic hazard analysis (PSHA) and NEHRP provisions typically con...

Observations of the 2020 M 5.7 Magna earthquake suggest that the event occurred on a listric portion of the Wasatch fault. This possibility represents a paradigm shift in our understanding of the seismic hazards in the region, with the potential for higher than previously estimated levels of strong ground shaking along many portions of the Wasatch...

In this special session, the seismological and geological aspects of the 2020 M 5.7 Magna, Utah earthquake, its impact on buildings and infrastructure, and implications for seismic hazard and risk along the Wasatch Front will be discussed. It is appropriate to look back at this recent event and the lessons learned from it, given the location of the...

Statewide probabilistic seismic hazard maps were developed for the South Carolina Department of Transportation (SCDOT). The maps were developed for hard rock (VS 3,000 m/sec) and reference outcrop site conditions (VS30 800 to 2,400 m/sec in the Piedmont and 350 to 400 m/sec in the Coastal Plain) and four return periods relevant to transportation sy...

The crust in the central and eastern U.S. is thought to be critically stressed and past seismicity indicates the presence of faults that may cause future earthquakes. Because carbon capture, utilization, and storage (CCUS) can perturb the state-of-stress on pre-existing faults leading them to premature failure, characterizing the potential for indu...

South Carolina (SC) is one of the seismically active states in the central and eastern US, and there is a need for calculating the site-specific hazards for the design of civil infrastructure systems. In this paper, the capabilities of a new ground motion generator that is being developed considering the local seismic and geological conditions are...

The Sacramento-San Joaquin Delta in central California is particularly susceptible to damage in a large earthquake due to the vulnerability of the levees that protect cities, farms, and infrastructure. The Delta is located adjacent to the seismically active San Andreas fault system and is also subject to strong ground shaking from numerous other se...

The damaging 4 May 2018 M 6.9 Kalapana earthquake and its aftershocks have provided the largest suite of strong motion records ever produced for an earthquake sequence in Hawaii exceeding the number of records obtained in the deep 2006 M 6.7 Kiholo Bay earthquake. These records provided the best opportunity to understand the processes of strong gro...

In this study, a ground-motion model (GMM) for deep intraslab subduction zone earthquakes in northeastern India (NEI) and adjacent regions, including portions of Bangladesh, Bhutan, China, Myanmar, and Nepal, is developed. Strong-motion data for deep intraslab earthquakes in NEI are very sparse, so it is not possible to develop a robust empirical G...

In the National Seismic Hazard Maps, the U.S. Geological Survey (USGS) uses ground-motion models (GMMs) appropriate for both the central and eastern United States (CEUS) and the western United States (WUS) for the Rocky Mountains and Colorado plateau, which includes much of Colorado and Wyoming, eastern Utah, northeastern Arizona, and northwestern...

Over the past 30 years, we have performed site-specific probabilistic and deterministic (scenario) seismic hazard analyses and compared the results for more than 250 U.S. dams and also compared our hazard estimates with the USGS National Seismic Hazard Maps. Based on these estimates and comparisons, we highlight several issues with regards to the c...

The Peru-Chile portion of the South America subduction zone is one of the most seismically active regions in the world and the source of some of the largest known earthquakes, including the 1960 moment magnitude (M) 9.5 Great Chile earthquake and more recently, the 2010 M 8.8 Maule earthquake. Since the beginning of the historical record in the mid...

Northwestern Peru is a highly seismically active region situated above the downgoing Nazca plate within the South America subduction zone. Historically, a total of 28 earthquakes of moment magnitude (M) 7.0 and greater have occurred in the region, including the 1619 M 7.7 to 8 Trujillo earthquake. Several active crustal faults have been identified...

In our article Kulkarni et al. (2013), we favored a clustered model for great Cascadia subduction zone (CSZ) earthquakes and our statistical analysis resulted in a probability of 0.65 that clustering was present in the turbidite record. The CSZ clustering analysis was originally motivated by the need to develop a CSZ logic tree for use in probabili...

In this study, a stochastic point-source model is used to develop a ground-motion prediction model for northeastern India (NEI) crustal earthquakes calibrated using region-specific source, path, and site parameters. The NEI strong ground motion database is too limited to derive an empirical ground-motion prediction model valid for all magnitudes an...

Until recently, no ground motion prediction model was available for deep (>20 km) Hawaiian earthquakes, including the 2006 M6.7 Kiholo Bay earthquake. We developed such a model based on the stochastic point-source model. Strong motion data from the 2006 event and 15 other deep Hawaiian earthquakes of M3.3 to M6.2 were inverted using a nonlinear lea...

The occurrence of several recent “extreme” earthquakes with their significant loss of life and the apparent failure to have been prepared for such disasters has raised the question of whether such events are accounted for in modern seismic hazard analyses. In light of the great 2011 Tohoku-Oki earthquake, were the questions of “how big, how bad, an...

As part of the BC Hydro Probabilistic Seismic Hazard Analysis Model Project, we have developed a new seismic source model of the Cascadia subduction zone (CSZ) using a logic tree approach. The five most significant CSZ seismic source parameters to hazard in the Pacific Northwest are: segmentation, the location of the eastern edge of the megathrust...

Anchorage is situated in one of the most seismically active regions in the U.S. The Alaskan subduction zone, which underlies the city, is the source of the 1964 M 9.2 Great Alaskan earthquake. Wadati-Benioff earthquakes within the subducting Pacific plate and crustal faults such as the Castle Mountain fault and nearby faults in Cook Inlet could als...

In probabilistic seismic-hazard analysis (PSHA), seismic source zone (SSZ) models are widely used to account for the contribution to the hazard from earthquakes not directly correlated with geological structures. Notwithstanding the impact of SSZ models in PSHA, the theoretical framework underlying SSZ models and the criteria used to delineate the...

Goldfinger et al. (2012) interpreted a 10,000-year old sequence of deep sea turbidites at the Cascadia subduction zone (CSZ) as a record of clusters of plate-boundary great earthquakes separated by gaps of many hundreds of years. We performed statistical analyses on this inferred earthquake record to test the temporal clustering model and calculate...

This Protocol is a living guidance document for geothermal developers, public officials, regulators and the general public that provides a set of general guidelines detailing useful steps to evaluate and manage the effects of induced seismicity related to EGS projects.

To assess the level and nature of ground shaking in Hawaii for the purposes of earthquake hazard mitigation and seismic design, empirical ground-motion prediction models are desired. To develop such empirical relationships, knowledge of the subsurface site conditions beneath strong-motion stations is critical. Thus, as a first step to develop groun...

The 2001 M 6.8 Nisqually, Washington, earthquake was recorded by more than 70 strong motion sites in and around the Puget Sound region. We have characterized the shear-wave velocity (V-S) structure down to depths of 100 to 300 ft at the 32 permanent strong motion sites, which recorded the highest ground motions (peak horizontal ground accelerations...

The purpose of this study is to determine intermediate (250 ft (75 m) to 750 ft (230 m)) to deep (> 750 ft (230 m)) shear‐wave velocity (Vs) profiles in the Salt Lake Valley. The Spectral‐Analysis‐of‐Surface‐Waves (SASW) method was used in the field to profile 11 locations. Vs profiles from this work have been provided to the Utah Ground Shaking Wo...

Recent digital maps from both new mapping and digitized old maps, can be used for new interactive GIS applications and web based access. Digital data can be combined for geohazard evaluations giving rapid low cost preliminary risk evaluations over large areas. for pipeline applications, this is useful in planning, design and maintenance data archiv...

Welcome Seismological Society of America meeting attendees to Portland, Oregon, my hometown! Home of clear blue skies (when it's not raining), the beautiful Willamette (Wil-LAM-ette) and Columbia rivers, creeks and lakes galore, majestic volcanic peaks (look to the north and east if it's a clear day), green trees, trees, and more trees, delicious p...

The amount of new information that has become available in the past decade on the earthquake potential of the Cascadia subduction zone (CSZ) and crustal faults in the Pacific Northwest has been astonishing. This observation seems even more surprising given the wealth of data that resulted in revolutionary changes in our understanding of Pacific Nor...

The development of seismogenic source models is one of the first steps in seismic hazard assessment. In seismic hazard terminology, seismic source zones (SSZ) are polygons (or volumes) that delineate areas with homogeneous characteristics of seismicity. The importance of using knowledge on geology, seismicity and tectonics in the definition of sour...

Earthquakes of the Teton–Yellowstone region represent a high level of seismicity in the Intermountain west (U.S.A.) that is associated with intraplate extension associated with the Yellowstone hotspot including the nearby Teton and Hebgen Lake faults. The seismicity and the occurrence of high slip-rate late Quaternary faults in this region leads to...

As demonstrated in the 2006 M 6.7 Kiholo Bay earthquake, where some strong motion stations recorded peak horizontal accelerations close to 1g, site response effects can be significant on the Big Island. As part of FEMA-supported studies following the earthquake, we have produced a new 1:100,000-scale map of site conditions for the Big Island of Haw...