Earthquake Hazard in the Eastern United States: Consequences of Alternative Seismic Source Zones

1987 ◽  
Vol 3 (2) ◽  
pp. 227-261 ◽  
Author(s):  
P. C. Thenhaus ◽  
D. M. Perkins ◽  
S. T. Algermissen ◽  
S. L. Hanson
Keyword(s):  
United States ◽  
South Carolina ◽  
Ground Motion ◽  
Seismic Source ◽  
Source Zone ◽  
Zone Model ◽  
Maximum Magnitude ◽  
Eastern United States ◽  
Thrust Tectonics ◽  
Source Zones

The regional variability in expected ground motion associated with six different characterizations of seismic source zones for probabilistic ground motion assessment is examined for the eastern United States. Three of the seismic source zone models are based on types of geologic structure: (1) regions characterized by late-Precambrian faulting; (2) middle-to-late Paleozoic thrust tectonics; and (3) early-to-middle Mesozoic extensional features. Two other seismic source zone configurations considered are based on data related to vertical crustal movements, and the final source zone model investigated is that of Algermissen and others (1982). Maintaining the same maximum magnitude among all zones and for all source zone configurations, a comparison of results indicates a factor of 3 difference among source zone models for calculated acceleration levels in eastern Massachusetts, southeastern Maine, and the Cape Fear arch of eastern North Carolina; a factor of about 2 or greater difference for most other eastern seaboard areas; and a factor of 1.5 or less for much of the Appalachian region extending from New Brunswick to the Gulf Coast. Results show that certain source zone models based exclusively on speculative geologic hypotheses result in considerably lower ground-motion hazard than otherwise implied by accepting historical seismicity as a guide to future hazard. Significantly, variation in the seismic hazard estimates at probability levels of 1 in 500 due to uncertain earthquake causal structures or processes is considerably higher in the heavily populated northeast region than in the Charleston, South Carolina, area.

The January 4, 1989, Earthquake in Bluffton, South Carolina, and its Tectonic Implications

1991 ◽  
Vol 62 (2) ◽  
pp. 139-142
Author(s):  
P. Talwani ◽  
K. Rajendran
Keyword(s):  
South Carolina ◽  
Ground Motion ◽  
Coastal Plain ◽  
Seismic Source ◽  
Early Morning ◽  
Source Zone ◽  
The Past ◽  
Tectonic Implications ◽  
Lower South ◽  
Head Area

Abstract An earthquake of magnitude 2.8 occurred on January 4, 1989, at 9:39:01.47 UTC (4:39 am EST) near Bluffton, in the lower South Carolina Coastal Plain, a region of low seismicity. More than seventy people in the Bluffton-Hilton Head area reported either hearing or feeling this early morning event. Historically, there have been three earthquakes, two of which had a MMI ≥ V, near Savannah, 25 km southwest of this earthquake. Recent discoveries of earthquake induced liquefaction features in the Bluffton area suggested that this area had been subjected to large ground motion in the past. Together, these data lead to the preliminary inference of a possible seismic source zone near Bluffton.

scholarly journals Seismic Hazard in the Nation's Breadbasket

2015 ◽  
Vol 31 (1_suppl) ◽  
pp. S109-S130 ◽  
Author(s):  
Oliver Boyd ◽  
Kathleen Haller ◽  
Nico Luco ◽  
Morgan Moschetti ◽  
Charles Mueller ◽  
...  
Keyword(s):  
United States ◽  
Seismic Hazard ◽  
Ground Motion ◽  
Nearest Neighbor ◽  
Seismic Source ◽  
Eastern United States ◽  
Source Characterization ◽  
Nuclear Facilities ◽  
Motion Models ◽  
Ground Motion Models

The USGS National Seismic Hazard Maps were updated in 2014 and included several important changes for the central United States (CUS). Background seismicity sources were improved using a new moment-magnitude-based catalog; a new adaptive, nearest-neighbor smoothing kernel was implemented; and maximum magnitudes for background sources were updated. Areal source zones developed by the Central and Eastern United States Seismic Source Characterization for Nuclear Facilities project were simplified and adopted. The weighting scheme for ground motion models was updated, giving more weight to models with a faster attenuation with distance compared to the previous maps. Overall, hazard changes (2% probability of exceedance in 50 years, across a range of ground-motion frequencies) were smaller than 10% in most of the CUS relative to the 2008 USGS maps despite new ground motion models and their assigned logic tree weights that reduced the probabilistic ground motions by 5–20%.

Treatment of Parameter Uncertainty and Variability for a Single Seismic Hazard Map

1993 ◽  
Vol 9 (2) ◽  
pp. 165-195 ◽  
Author(s):  
Bernice K. Bender ◽  
David M. Perkins
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Seismic Source ◽  
B Value ◽  
Source Zone ◽  
Probabilistic Seismic Hazard ◽  
Maximum Magnitude ◽  
Hazard Map ◽  
Mean Values ◽  
Seismic Hazard Map

The inputs to probabilistic seismic hazard studies (seismic source zones, earthquake rates, attenuation functions, etc.) are uncertain, being based on subjective judgments and interpretations of limited data. In the face of this uncertainty, we consider (a) how one might “reasonably” determine the ground-motion levels to show on a single probabilistic seismic hazard map, and (b) the extent to which uncertainty in the calculated levels can be meaningfully represented on such a map. If the “best guess” estimates of the earthquake rate, the Gutenberg-Richter b-value and the maximum magnitude for a single source zone are regarded as uncorrelated and the uncertainty in each parameter can be regarded as symmetric about the estimated value, then the probabilistic ground-motion levels calculated using these best estimates represent both most likely values and also approximate mean values.

Seismic Hazard in the Eastern United States

2015 ◽  
Vol 31 (1_suppl) ◽  
pp. S85-S107 ◽  
Author(s):  
Charles S. Mueller ◽  
Oliver S. Boyd ◽  
Mark D. Petersen ◽  
Morgan P. Moschetti ◽  
Sanaz Rezaeian ◽  
...  
Keyword(s):  
United States ◽  
Seismic Hazard ◽  
New England ◽  
Ground Motion ◽  
Maximum Magnitude ◽  
Eastern United States ◽  
Adaptive Smoothing ◽  
Motion Models ◽  
Background Seismicity ◽  
Ground Motion Models

The U.S. Geological Survey seismic hazard maps for the central and eastern United States were updated in 2014. We analyze results and changes for the eastern part of the region. Ratio maps are presented, along with tables of ground motions and deaggregations for selected cities. The Charleston fault model was revised, and a new fault source for Charlevoix was added. Background seismicity sources utilized an updated catalog, revised completeness and recurrence models, and a new adaptive smoothing procedure. Maximum-magnitude models and ground motion models were also updated. Broad, regional hazard reductions of 5%–20% are mostly attributed to new ground motion models with stronger near-source attenuation. The revised Charleston fault geometry redistributes local hazard, and the new Charlevoix source increases hazard in northern New England. Strong increases in mid- to high-frequency hazard at some locations—for example, southern New Hampshire, central Virginia, and eastern Tennessee—are attributed to updated catalogs and/or smoothing.

scholarly journals A ground motion logic tree for seismic hazard analysis in the stable cratonic region of Europe: regionalisation, model selection and development of a scaled backbone approach

2020 ◽  
Vol 18 (14) ◽  
pp. 6119-6148
Author(s):  
Graeme Weatherill ◽  
Fabrice Cotton
Keyword(s):  
United States ◽  
Seismic Hazard ◽  
Ground Motion ◽  
Epistemic Uncertainty ◽  
Hazard Analysis ◽  
Seismic Hazard Analysis ◽  
Eastern United States ◽  
Logic Tree ◽  
Short Period ◽  
Northeastern Europe

Abstract Regions of low seismicity present a particular challenge for probabilistic seismic hazard analysis when identifying suitable ground motion models (GMMs) and quantifying their epistemic uncertainty. The 2020 European Seismic Hazard Model adopts a scaled backbone approach to characterise this uncertainty for shallow seismicity in Europe, incorporating region-to-region source and attenuation variability based on European strong motion data. This approach, however, may not be suited to stable cratonic region of northeastern Europe (encompassing Finland, Sweden and the Baltic countries), where exploration of various global geophysical datasets reveals that its crustal properties are distinctly different from the rest of Europe, and are instead more closely represented by those of the Central and Eastern United States. Building upon the suite of models developed by the recent NGA East project, we construct a new scaled backbone ground motion model and calibrate its corresponding epistemic uncertainties. The resulting logic tree is shown to provide comparable hazard outcomes to the epistemic uncertainty modelling strategy adopted for the Eastern United States, despite the different approaches taken. Comparison with previous GMM selections for northeastern Europe, however, highlights key differences in short period accelerations resulting from new assumptions regarding the characteristics of the reference rock and its influence on site amplification.

A comparison of earthquake damage areas as a function of magnitude across the United States

1993 ◽  
Vol 83 (4) ◽  
pp. 1064-1080 ◽  
Author(s):  
G. A. Bollinger ◽  
M. C. Chapman ◽  
M. S. Sibol
Keyword(s):  
United States ◽  
North America ◽  
Ground Motion ◽  
Epicentral Distance ◽  
The United States ◽  
Western United States ◽  
Eastern North America ◽  
Similar Response ◽  
Eastern United States ◽  
The West

Abstract This study investigates the relationship between earthquake magnitude and the size of damage areas in the eastern and western United States. To quantify damage area as a function of moment magnitude (M), 149 MMI VI and VII areas for 109 earthquakes (88 in the western United States, 21 in the eastern United States and Canada) were measured. Regression of isoseismal areas versus M indicated that areas in the East were larger than those in the West, at both intensity levels, by an average 5 × in the M 4.5 to 7.5 range. In terms of radii for circles of equivalent area, these results indicate that damaging ground motion from shocks of the same magnitude extend 2 × the epicentral distance in eastern North America compared to the West. To determine source and site parameters consistent with the above results, response spectral levels for eastern North America were stochastically simulated and compared with response spectral ordinates derived from recorded strong ground motion data in the western United States. Stress-drop values of 200 bars, combined with a surficial 2-km-thick low velocity “sedimentary” layer over rock basement, produced results that are compatible with the intensity observations, i.e., similar response spectral levels in the east at approximately twice their epicentral distance in the western U.S. distance. These results suggest that ground motion modeling in eastern North America may need to incorporate source and site parameters different from those presently in general use. The results are also of importance to eastern U.S. hazard assessments as they require allowance for the larger damage areas in preparedness and mitigation programs.

scholarly journals A seismic source zone model for the seismic hazard assessment of Slovakia

2016 ◽  
Vol 67 (3) ◽  
pp. 275-290 ◽  
Author(s):  
Jozef Hók ◽  
Robert Kysel ◽  
Michal Kováč ◽  
Peter Moczo ◽  
Jozef Kristek ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Hazard Assessment ◽  
Large Scale ◽  
Seismic Hazard Assessment ◽  
Seismic Source ◽  
Source Zone ◽  
Zone Model ◽  
Geological Structures ◽  
Seismotectonic Model ◽  
Seismogenic Structures

Abstract We present a new seismic source zone model for the seismic hazard assessment of Slovakia based on a new seismotectonic model of the territory of Slovakia and adjacent areas. The seismotectonic model has been developed using a new Slovak earthquake catalogue (SLOVEC 2011), successive division of the large-scale geological structures into tectonic regions, seismogeological domains and seismogenic structures. The main criteria for definitions of regions, domains and structures are the age of the last tectonic consolidation of geological structures, thickness of lithosphere, thickness of crust, geothermal conditions, current tectonic regime and seismic activity. The seismic source zones are presented on a 1:1,000,000 scale map.

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