A Comparison between the Forecast by the United States National Seismic Hazard Maps with Recent Ground‐Motion Records

The National Seismic Hazard Maps (NSHMs) are an important component of seismic design regulations in the United States. This paper compares hazard using the new suite of ground motion models (GMMs) relative to hazard using the suite of GMMs applied in the previous version of the maps. The new source characterization models are used for both cases. A previous paper ( Rezaeian et al. 2014 ) discussed the five NGA-West2 GMMs used for shallow crustal earthquakes in the Western United States (WUS), which are also summarized here. Our focus in this paper is on GMMs for earthquakes in stable continental regions in the Central and Eastern United States (CEUS), as well as subduction interface and deep intraslab earthquakes. We consider building code hazard levels for peak ground acceleration (PGA), 0.2-s, and 1.0-s spectral accelerations (SAs) on uniform firm-rock site conditions. The GMM modifications in the updated version of the maps created changes in hazard within 5% to 20% in WUS; decreases within 5% to 20% in CEUS; changes within 5% to 15% for subduction interface earthquakes; and changes involving decreases of up to 50% and increases of up to 30% for deep intraslab earthquakes for most U.S. sites. These modifications were combined with changes resulting from modifications in the source characterization models to obtain the new hazard maps.

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Implementation of NGA-West2 Ground Motion Models in the 2014 U.S. National Seismic Hazard Maps

Earthquake Spectra ◽

10.1193/062913eqs177m ◽

2014 ◽

Vol 30 (3) ◽

pp. 1319-1333 ◽

Cited By ~ 16

Author(s):

Sanaz Rezaeian ◽

Mark D. Petersen ◽

Morgan P. Moschetti ◽

Peter Powers ◽

Stephen C. Harmsen ◽

...

Keyword(s):

United States ◽

Seismic Hazard ◽

Ground Motion ◽

The United States ◽

Hazard Maps ◽

Seismic Hazard Maps ◽

Motion Models ◽

Seismic Source Models ◽

Ground Motion Models ◽

The U.S

The U.S. National Seismic Hazard Maps (NSHMs) have been an important component of seismic design regulations in the United States for the past several decades. These maps present earthquake ground shaking intensities at specified probabilities of being exceeded over a 50-year time period. The previous version of the NSHMs was developed in 2008; during 2012 and 2013, scientists at the U.S. Geological Survey have been updating the maps based on their assessment of the “best available science,” resulting in the 2014 NSHMs. The update includes modifications to the seismic source models and the ground motion models (GMMs) for sites across the conterminous United States. This paper focuses on updates in the Western United States (WUS) due to the use of new GMMs for shallow crustal earthquakes in active tectonic regions developed by the Next Generation Attenuation (NGA-West2) project. Individual GMMs, their weighted combination, and their impact on the hazard maps relative to 2008 are discussed. In general, the combined effects of lower medians and increased standard deviations in the new GMMs have caused only small changes, within 5–20%, in the probabilistic ground motions for most sites across the WUS compared to the 2008 NSHMs.

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Documentation for the 2008 update of the United States National Seismic Hazard Maps

Open-File Report ◽

10.3133/ofr20081128 ◽

2008 ◽

Cited By ~ 163

Author(s):

Mark D. Petersen ◽

Arthur D. Frankel ◽

Stephen C. Harmsen ◽

Charles S. Mueller ◽

Kathleen M. Haller ◽

...

Keyword(s):

United States ◽

Seismic Hazard ◽

The United States ◽

Hazard Maps ◽

Seismic Hazard Maps

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USGS National Seismic Hazard Maps

Earthquake Spectra ◽

10.1193/1.1586079 ◽

2000 ◽

Vol 16 (1) ◽

pp. 1-19 ◽

Cited By ~ 88

Author(s):

A. D. Frankel ◽

C. S. Mueller ◽

T. P. Barnhard ◽

E. V. Leyendecker ◽

R. L. Wesson ◽

...

Keyword(s):

United States ◽

South Carolina ◽

Seismic Hazard ◽

Spectral Response ◽

The United States ◽

Great Earthquake ◽

Hazard Maps ◽

Seismic Hazard Maps ◽

Large Earthquakes ◽

Historic Seismicity

The U.S. Geological Survey (USGS) recently completed new probabilistic seismic hazard maps for the United States, including Alaska and Hawaii. These hazard maps form the basis of the probabilistic component of the design maps used in the 1997 edition of the NEHRP Recommended Provisions for Seismic Regulations for New Buildings and Other Structures, prepared by the Building Seismic Safety Council and published by FEMA. The hazard maps depict peak horizontal ground acceleration and spectral response at 0.2, 0.3, and 1.0 sec periods, with 10%, 5%, and 2% probabilities of exceedance in 50 years, corresponding to return times of about 500, 1000, and 2500 years, respectively. In this paper we outline the methodology used to construct the hazard maps. There are three basic components to the maps. First, we use spatially smoothed historic seismicity as one portion of the hazard calculation. In this model, we apply the general observation that moderate and large earthquakes tend to occur near areas of previous small or moderate events, with some notable exceptions. Second, we consider large background source zones based on broad geologic criteria to quantify hazard in areas with little or no historic seismicity, but with the potential for generating large events. Third, we include the hazard from specific fault sources. We use about 450 faults in the western United States (WUS) and derive recurrence times from either geologic slip rates or the dating of pre-historic earthquakes from trenching of faults or other paleoseismic methods. Recurrence estimates for large earthquakes in New Madrid and Charleston, South Carolina, were taken from recent paleoliquefaction studies. We used logic trees to incorporate different seismicity models, fault recurrence models, Cascadia great earthquake scenarios, and ground-motion attenuation relations. We present disaggregation plots showing the contribution to hazard at four cities from potential earthquakes with various magnitudes and distances.

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Documentation for the 2014 update of the United States national seismic hazard maps

Open-File Report ◽

10.3133/ofr20141091 ◽

2014 ◽

Cited By ~ 141

Author(s):

Mark D. Petersen ◽

Morgan P. Moschetti ◽

Peter M. Powers ◽

Charles S. Mueller ◽

Kathleen M. Haller ◽

...

Keyword(s):

United States ◽

Seismic Hazard ◽

The United States ◽

Hazard Maps ◽

Seismic Hazard Maps

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Site-specific seismic-hazard maps and deaggregation in the western United States using the NGA models for ground-motion prediction

Open-File Report ◽

10.3133/ofr20111218 ◽

2011 ◽

Cited By ~ 1

Author(s):

Stephen Harmsen

Keyword(s):

United States ◽

Seismic Hazard ◽

Ground Motion ◽

Western United States ◽

Motion Prediction ◽

Hazard Maps ◽

Ground Motion Prediction ◽

Site Specific ◽

Seismic Hazard Maps

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Proposal of orientation-independent measure of intensity for earthquake-resistant design

Earthquake Spectra ◽

10.1177/87552930211038240 ◽

2021 ◽

pp. 875529302110382

Author(s):

Alan Poulos ◽

Eduardo Miranda

Keyword(s):

United States ◽

Ground Motion ◽

The United States ◽

Design Codes ◽

Intensity Measure ◽

Independent Measure ◽

Earthquake Resistant Design ◽

Earthquake Resistant ◽

Ground Motion Records ◽

Structural Engineers

A new measure of ground motion intensity in the horizontal direction is proposed. Similarly to other recently proposed measures of intensity, the proposed intensity measure is also independent of the as-installed orientation of horizontal sensors at recording stations. This new measure of horizontal intensity, referred to as MaxRotD50, is defined using the maximum 5%-damped response spectral ordinate of two orthogonal horizontal directions and then computing the 50th percentile for all non-redundant rotation angles, that is, the median of the set of spectral ordinates in a range of 90°. This proposed measure of intensity is always between the median and maximum spectral ordinate for all non-redundant orientations, commonly referred to as RotD50 and RotD100, respectively. A set of 5065 ground motion records is used to show that MaxRotD50 is, on average, approximately 13%–16% higher than Rot50 and 6% lower than RotD100. The new measure of intensity is particularly well suited for earthquake-resistant design where a major concern for structural engineers is the probability that the design ground motion intensity is exceeded in at least one of the two principal horizontal components of the structure, which for most structures are orthogonal to each other. Currently, design codes in the United States are based on RotD100, and hence using MaxRotD50 for structures with two orthogonal principal horizontal components would result in a reduction of the ground motion intensities used for design purposes.

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Probabilistic seismic hazard maps for California do not perform better relative to historical shaking data when site-specific VS30 is considered

10.5194/egusphere-egu21-6633 ◽

2021 ◽

Author(s):

Molly Gallahue ◽

Leah Salditch ◽

Madeleine Lucas ◽

James Neely ◽

Susan Hough ◽

...

Keyword(s):

Seismic Hazard ◽

Ground Motion ◽

Tall Buildings ◽

Historical Period ◽

Probabilistic Seismic Hazard ◽

Hazard Maps ◽

Site Specific ◽

Seismic Hazard Maps ◽

Intensity Mapping ◽

Aleatory Variability

<div> <p>Probabilistic seismic hazard assessments forecast levels of earthquake shaking that should be exceeded with only a certain probability over a given period of time are important for earthquake hazard mitigation. These rely on assumptions about when and where earthquakes will occur, their size, and the resulting shaking as a function of distance as described by ground-motion models (GMMs) that cover broad geologic regions. Seismic hazard maps are used to develop building codes.</p> </div><div> <p>To explore the robustness of maps&#8217; shaking forecasts, we consider how maps hindcast past shaking. We have compiled the California Historical Intensity Mapping Project (CHIMP) dataset of the maximum observed seismic intensity of shaking from the largest Californian earthquakes over the past 162 years. Previous comparisons between the maps for a constant V<sub>S30</sub> (shear-wave velcoity in the top 30 m of soil) of 760 m/s and CHIMP based on several metrics suggested that current maps overpredict shaking.</p> <p>The differences between the V<sub>S30</sub> at the CHIMP sites and the reference value of 760 m/s could amplify or deamplify the ground motions relative to the mapped values. We evaluate whether the V<sub>S30 </sub>at the CHIMP sites could cause a possible bias in the models.&#160;By comparison with the intensity data in CHIMP, we find that using site-specific V<sub>S30</sub> does not improve map performance, because the site corrections cause only minor differences from the original 2018 USGS hazard maps at the short periods (high frequencies) relevant to peak ground acceleration and hence MMI. The minimal differences reflect the fact that the nonlinear deamplification due to increased soil damping largely offsets the linear amplification due to low V<sub>S30</sub>. The net effects will be larger for longer periods relevant to tall buildings, where net amplification occurs.&#160;</p> <div> <p>Possible reasons for this discrepancy include&#160;limitations of the dataset, a bias in the hazard models, an over-estimation of the aleatory variability of the ground motion or that seismicity throughout the historical period has been lower than the long-term average, perhaps by chance due to the variability of earthquake recurrence. Resolving this discrepancy, which is also observed in Italy and Japan, could improve the performance of seismic hazard maps and thus earthquake safety for California and, by extension, worldwide. We also explore whether new nonergodic GMMs, with reduced aleatory variability, perform better than presently used ergodic GMMs compared to historical data.</p> </div> </div>

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Variabilities in probabilistic seismic hazard maps for natural and induced seismicity in the central and eastern United States

The Leading Edge ◽

10.1190/tle37020141a1.1 ◽

2018 ◽

Vol 37 (2) ◽

pp. 141a1-141a9 ◽

Cited By ~ 3

Author(s):

S. Mostafa Mousavi ◽

Gregory C. Beroza ◽

Susan M. Hoover

Keyword(s):

United States ◽

Seismic Hazard ◽

Induced Seismicity ◽

Probabilistic Seismic Hazard ◽

Eastern United States ◽

Hazard Maps ◽

Seismic Hazard Maps

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Seismic hazard maps of Peshawar District for various return periods

Natural Hazards and Earth System Science ◽

10.5194/nhess-20-1639-2020 ◽

2020 ◽

Vol 20 (6) ◽

pp. 1639-1661

Author(s):

Khalid Mahmood ◽

Naveed Ahmad ◽

Usman Khan ◽

Qaiser Iqbal

Keyword(s):

Seismic Hazard ◽

Ground Motion ◽

Target Location ◽

Epistemic Uncertainty ◽

Hazard Analysis ◽

Source Parameters ◽

Seismic Source ◽

Return Periods ◽

Hazard Maps ◽

Seismic Hazard Maps

Abstract. Probabilistic seismic hazard analysis of Peshawar District has been performed for a grid size of 0.01∘. The seismic sources for the target location are defined as the area polygon with uniform seismicity. The earthquake catalogue was developed based on the earthquake data obtained from different worldwide seismological networks and historical records. The earthquake events obtained at different magnitude scales were converted into moment magnitude using indigenous catalogue-specific regression relationships. The homogenized catalogue was subdivided into shallow crustal and deep-subduction-zone earthquake events. The seismic source parameters were obtained using the bounded Gutenberg–Richter recurrence law. Seismic hazard maps were prepared for peak horizontal acceleration at bedrock level using different ground motion attenuation relationships. The study revealed the selection of an appropriate ground motion prediction equation is crucial for defining the seismic hazard of Peshawar District. The inclusion of deep subduction earthquakes does not add significantly to the seismic hazard for design base ground motions. The seismic hazard map developed for shallow crustal earthquakes, including also the epistemic uncertainty, was in close agreement with the map given in the Building Code of Pakistan Seismic Provisions (2007) for a return period of 475 years on bedrock. The seismic hazard maps for other return periods i.e., 50, 100, 250, 475 and 2500 years, are also presented.

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