I specialize in the development of earthquake-forecast models, which are one of the two main modeling components used in modern seismic-hazard analysis (the other being a ground-motion model).

My focus area has mainly been California, which due to an abundance of riches in terms of both scientific talent and data constraints, has enabled the forging of state-or-the-art methodologies (California also hosts trillions of dollars in assets and, consequently, two-thirds of the nationwide seismic risk). The multi-disciplinary nature of earthquake forecasting necessitates a collaborative approach, which we have achieved through the Working Group on California Earthquake Probabilities (www.WGCEP.org). I led the development of our most recent model, the Third Uniform California Earthquake Rupture Forecast (UCERF3; www.WGCEP.org/UCERF3), which is innovative in terms of representing both multi-fault ruptures and spatiotemporal clustering (e.g. aftershocks); the relevance of both these effects was dramatically exemplified in a recent sequence of damaging earthquakes in New Zealand. Our forecast models influence a variety of risk mitigation activities, including construction requirements (building codes) and insurance rates. Important themes going forward include: a better quantification of uncertainties; the use of more physics-based approaches; and the need to add “valuation” to our verification and validation protocols (“all models are wrong” at some level, so a relevant question is whether a new and improved one really represents value added with respect to risk assessment).

I have also led the development of OpenSHA (http://www.OpenSHA.org), which is an object-oriented, GUI-enabled, open-source, and platform-independent computational framework for conducting seismic hazard analysis. OpenSHA also makes use of distributed object technologies (components can exist anywhere over the Internet), it runs on high-performance super computers, and it supports loss modeling as well.

I am also a member of the planning committee of the Southern California Earthquake Center (http://www.SCEC.org), and as such, I help formulated the SCEC science plan, write the annual RFPs, and review and recommend funding levels for proposals submitted to SCEC.

## Science and Products

#### Could the M7.1 Ridgecrest, CA Earthquake Sequence Trigger a Large Earthquake Nearby?

#### Could the M7.1 Ridgecrest, CA Earthquake Sequence Trigger a Large Earthquake Nearby?

#### Operational Earthquake Forecasting – Implementing a Real-Time System for California

#### Operational Earthquake Forecasting – Implementing a Real-Time System for California

#### Joint USGS - GEM Group on Global Probabilistic Modeling of Earthquake Recurrence Rates and Maximum Magnitudes

#### Joint USGS - GEM Group on Global Probabilistic Modeling of Earthquake Recurrence Rates and Maximum Magnitudes

#### Earthquake geology inputs for the U.S. National Seismic Hazard Model (NSHM) 2023, version 1.0

#### Shakemap earthquake scenario: Building Seismic Safety Council 2014 Event Set (BSSC2014)

#### Seismic-hazard maps for the conterminous United States, 2014

#### Seismic-Hazard Maps for the Conterminous United States, 2008

#### Some systemic risks to progress on seismic hazard assessment

#### STEPS: Slip time earthquake path simulations applied to the San Andreas and Toe Jam Hill Faults to redefine geologic slip rate uncertainty

#### The seismic hazard implications of declustering and poisson assumptions inferred from a fully time‐dependent model

#### Improvements to the Third Uniform California Earthquake Rupture Forecast ETAS Model (UCERF3‐ETAS)

#### The 2018 update of the US National Seismic Hazard Model: Where, why, and how much probabilistic ground motion maps changed

#### Toward physics-based nonergodic PSHA: A prototype fully-deterministic seismic hazard model for southern California

#### Generalizing the inversion‐based PSHA source model for an interconnected fault system

#### Pseudo-prospective evaluation of UCERF3-ETAS forecasts during the 2019 Ridgecrest sequence

#### Assessing the value of removing earthquake-hazard-related epistemic uncertainties, exemplified using average annual loss in California

#### Probabilistic seismic hazard analysis at regional and national scale: State of the art and future challenges

#### Operational earthquake forecasting during the 2019 Ridgecrest, California, earthquake sequence with the UCERF3-ETAS model

#### The 2018 update of the US National Seismic Hazard Model: Overview of model and implications

#### STEPS: Slip Time Earthquake Path Simulations applied to the San Andreas and Toe Jam Hill faults to redefine geologic slip rate uncertainty (Matlab code)

#### nshm-fault-sections

## Science and Products

- Science
#### Could the M7.1 Ridgecrest, CA Earthquake Sequence Trigger a Large Earthquake Nearby?

Release Date: SEPTEMBER 30, 2019Two of the first questions that come to mind for anyone who just felt an earthquake are, “Will there be another one?” and “Will it be larger?”.link#### Could the M7.1 Ridgecrest, CA Earthquake Sequence Trigger a Large Earthquake Nearby?

Release Date: SEPTEMBER 30, 2019Two of the first questions that come to mind for anyone who just felt an earthquake are, “Will there be another one?” and “Will it be larger?”.#### Operational Earthquake Forecasting – Implementing a Real-Time System for California

It is well know that every earthquake can spawn others (e.g., as aftershocks), and that such triggered events can be large and damaging, as recently demonstrated by L’Aquila, Italy and Christchurch, New Zealand earthquakes. In spite of being an explicit USGS strategic-action priority (http://pubs.usgs.gov/of/2012/1088; page 32), the USGS currently lacks an automated system with which to forecast s...link#### Operational Earthquake Forecasting – Implementing a Real-Time System for California

It is well know that every earthquake can spawn others (e.g., as aftershocks), and that such triggered events can be large and damaging, as recently demonstrated by L’Aquila, Italy and Christchurch, New Zealand earthquakes. In spite of being an explicit USGS strategic-action priority (http://pubs.usgs.gov/of/2012/1088; page 32), the USGS currently lacks an automated system with which to forecast s...#### Joint USGS - GEM Group on Global Probabilistic Modeling of Earthquake Recurrence Rates and Maximum Magnitudes

Despite the best monitoring networks, the highest rate of earthquakes and the longest continuous recorded history in the world, this year’s M=9.0 Tohoku, Japan, earthquake was completely unforeseen. The Japanese had expected no larger than a M=8 quake in the Japan trench, 1/30 th the size of the Tohoku temblor. This year also saw the devastating M=6.3 Christchurch, New Zealand earthquake and the M...linkDespite the best monitoring networks, the highest rate of earthquakes and the longest continuous recorded history in the world, this year’s M=9.0 Tohoku, Japan, earthquake was completely unforeseen. The Japanese had expected no larger than a M=8 quake in the Japan trench, 1/30 th the size of the Tohoku temblor. This year also saw the devastating M=6.3 Christchurch, New Zealand earthquake and the M... - Data
#### Earthquake geology inputs for the U.S. National Seismic Hazard Model (NSHM) 2023, version 1.0

This Data Release contains preliminary versions of two related databases: 1) A fault sections database (&quot;NSHM2023_FaultSections_v1&quot;), which depicts the geometry of faults capable of hosting independent earthquakes, and 2) An earthquake geology site information database (&quot;NSHM2023_EQGeoDB_v1&quot;), which contains fault slip-rate constraints at points. These databases#### Shakemap earthquake scenario: Building Seismic Safety Council 2014 Event Set (BSSC2014)

This is a catalog of earthquake scenarios, represented as ShakeMaps. A ShakeMap is a USGS product that facilitates communication of earthquake effects by portraying a map of the severity of shaking. Maps of shaking severity are provided in terms of macroseismic intensity, peak ground acceleration, peak ground velocity, and spectral accelerations (at 0.3, 1.0 and 3 sec oscillator periods). - Maps
#### Seismic-hazard maps for the conterminous United States, 2014

The maps presented here provide an update to the 2008 data contained in U.S Geological Survey Scientific Investigations Map 3195 (http://pubs.usgs.gov/sim/3195/).Probabilistic seismic-hazard maps were prepared for the conterminous United States for 2014 portraying peak horizontal acceleration and horizontal spectral response acceleration for 0.2- and 1.0-second periods with probabilities of exceed#### Seismic-Hazard Maps for the Conterminous United States, 2008

Probabilistic seismic-hazard maps were prepared for the conterminous United States portraying peak horizontal acceleration and horizontal spectral response acceleration for 0.2- and 1.0-second periods with probabilities of exceedance of 10 percent in 50 years and 2 percent in 50 years. All of the maps were prepared by combining the hazard derived from spatially smoothed historic seismicity with th - Publications
Filter Total Items: 47
#### Some systemic risks to progress on seismic hazard assessment

No abstract available.#### STEPS: Slip time earthquake path simulations applied to the San Andreas and Toe Jam Hill Faults to redefine geologic slip rate uncertainty

Geologic slip rates are a time-averaged measurement of fault displacement calculated over hundreds to million-year time scales and are a primary input for probabilistic seismic hazard analyses, which forecast expected ground shaking in future earthquakes. Despite their utility for seismic hazard calculations, longer-term geologic slip rates represent a time-averaged measure of the tempo of strain#### The seismic hazard implications of declustering and poisson assumptions inferred from a fully time‐dependent model

We use the Third Uniform California Earthquake Rupture Forecast (UCERF3) epidemic‐type aftershock sequence (ETAS) model (UCERF3‐ETAS) to evaluate the effects of declustering and Poisson assumptions on seismic hazard estimates. Although declustering is necessary to infer the long‐term spatial distribution of earthquake rates, the question is whether it is also necessary to honor the Poisson assumpt#### Improvements to the Third Uniform California Earthquake Rupture Forecast ETAS Model (UCERF3‐ETAS)

We describe recent improvements to the Third Uniform California Earthquake Rupture Forecast ETAS Model (UCERF3‐ETAS), which continues to represent our most advanced and complete earthquake forecast in terms of relaxing segmentation assumptions and representing multifault ruptures, elastic‐rebound effects, and spatiotemporal clustering (the latter to represent aftershocks and otherwise triggered ev#### The 2018 update of the US National Seismic Hazard Model: Where, why, and how much probabilistic ground motion maps changed

The 2018 US Geological Survey National Seismic Hazard Model (NSHM) incorporates new data and updated science to improve the underlying earthquake and ground motion forecasts for the conterminous United States. The NSHM considers many new data and component input models: (1) new earthquakes between 2013 and 2017 and updated earthquake magnitudes for some earlier earthquakes; (2) two updated smoothe#### Toward physics-based nonergodic PSHA: A prototype fully-deterministic seismic hazard model for southern California

We present a nonergodic framework for probabilistic seismic‐hazard analysis (PSHA) that is constructed entirely of deterministic, physical models. The use of deterministic ground‐motion simulations in PSHA calculations is not new (e.g., CyberShake), but prior studies relied on kinematic rupture generators to extend empirical earthquake rupture forecasts. Fully dynamic models, which simulate ruptur#### Generalizing the inversion‐based PSHA source model for an interconnected fault system

This article represents a step toward generalizing and simplifying the procedure for constructing an inversion‐based seismic hazard source model for an interconnected fault system, including the specification of adjustable segmentation constraints. A very simple example is used to maximize understandability and to counter the notion that an inversion approach is only applicable when an abundance o#### Pseudo-prospective evaluation of UCERF3-ETAS forecasts during the 2019 Ridgecrest sequence

The 2019 Ridgecrest sequence provides the first opportunity to evaluate Uniform California Earthquake Rupture Forecast v.3 with epidemic‐type aftershock sequences (UCERF3‐ETAS) in a pseudoprospective sense. For comparison, we include a version of the model without explicit faults more closely mimicking traditional ETAS models (UCERF3‐NoFaults). We evaluate the forecasts with new metrics developed#### Assessing the value of removing earthquake-hazard-related epistemic uncertainties, exemplified using average annual loss in California

To aid in setting scientific research priorities, we assess the potential value of removing each of the epistemic uncertainties currently represented in the US Geological Survey California seismic-hazard model, using average annual loss (AAL) as the risk metric of interest. Given all the uncertainties, represented with logic-tree branches, we find a mean AAL of $3.94 billion. The modal value is 17#### Probabilistic seismic hazard analysis at regional and national scale: State of the art and future challenges

Seismic hazard modelling is a multi-disciplinary science that aims to forecast earthquake occurrence and its resultant ground shaking. Such models consist of a probabilistic framework that quantifies uncertainty across a complex system; typically, this includes at least two model components developed from Earth science: seismic-source and ground-motion models. Although there is no scientific presc#### Operational earthquake forecasting during the 2019 Ridgecrest, California, earthquake sequence with the UCERF3-ETAS model

The first Uniform California Earthquake Rupture Forecast, Version 3–epidemic‐type aftershock sequence (UCERF3‐ETAS) aftershock simulations were running on a high‐performance computing cluster within 33 min of the 4 July 2019 M 6.4 Searles Valley earthquake. UCERF3‐ETAS, an extension of the third Uniform California Earthquake Rupture Forecast (UCERF3), is the first comprehensive, fault‐based, epide#### The 2018 update of the US National Seismic Hazard Model: Overview of model and implications

During 2017–2018, the National Seismic Hazard Model for the conterminous United States was updated as follows: (1) an updated seismicity catalog was incorporated, which includes new earthquakes that occurred from 2013 to 2017; (2) in the central and eastern United States (CEUS), new ground motion models were updated that incorporate updated median estimates, modified assessments of the associated - Software
#### STEPS: Slip Time Earthquake Path Simulations applied to the San Andreas and Toe Jam Hill faults to redefine geologic slip rate uncertainty (Matlab code)

Geologic slip rates are a time-averaged measurement of fault displacement calculated over 100s- to 1,000,000-year time scales and are a primary input for probabilistic seismic hazard analyses (PSHA), which forecast expected ground shaking in future earthquakes. Despite their utility for seismic hazard calculations, longer-term geologic slip rates represent a time-averaged measure of the tempo of s#### nshm-fault-sections

A repository of all geologic fault section data included in USGS National Seismic Hazard Models