A-1. Plot of probability of surface rupture relative to magnitude A-2. Plot of depth to top of surface rupture relative to magnitude for earthquakes in Next Generation Attenuation database B-1. Plot of multisegment fault as defined in 1996 and 2002 maps B-2. Plot of multisegment fault as defined in 2008 maps D-1. Diagram of a virtual dipping fault D-2. Plots showing effect of including hanging-wall term on median ground motion D-3. Plot showing the increase in Rjb for vertical faults F-1. Ground motions for two sites in the Central and Eastern United States without cluster model F-2. Ground motions for two sites in the Central and Eastern United States with cluster model G-1. Map of fault sources in the Intermountain West G-2. Slip-rate changes for Intermountain West faults H-1. Map of fault sources in the Pacific Northwest J-1. Plot showing increase in characteristic rate due to magnitude rounding J-2. Plot showing uncertainty in assigned slip rate for selected faults in Utah Appendix Tables: A-1. Depth to top of rupture E-1. Sampling interval details for non-California faults, truncated Gutenberg-Richter distribution G-1. Updated Intermountain West fault parameters G-2. Updated fault names for Intermountain West faults G-3. Intermountain West fault parameters by State H-1. Pacific Northwest fault parameters by State I-1. Rupture-model data for California Type-A faults I-2. List of significant changes to California Type-B faults I-3. Parameters for California Type-B faults I-4. Parameters for California Connected-B faults

The national seismic hazard maps for the conterminous United States have been updated to account for new methods, models, and data that have been obtained since the 2008 maps were released (Petersen and others, 2008). The input models are improved from those implemented in 2008 by using new ground motion models that have incorporated about twice as many earthquake strong ground shaking data and by incorporating many additional scientific studies that indicate broader ranges of earthquake source and ground motion models. These time-independent maps are shown for 2-percent and 10-percent probability of exceedance in 50 years for peak horizontal ground acceleration as well as 5-hertz and 1-hertz spectral accelerations with 5-percent damping on a uniform firm rock site condition (760 meters per second shear wave velocity in the upper 30 m, V S30). In this report, the 2014 updated maps are compared with the 2008 version of the maps and indicate changes of plus or minus 20 percent over wide areas, with larger changes locally, caused by the modifications to the seismic source and ground motion inputs.

No abstract

New seismic hazard maps have been developed for the conterminous United States using the latest data, models, and methods available for assessing earthquake hazard. The hazard models incorporate new information on earthquake rupture behavior observed in recent earthquakes; fault studies that use both geologic and geodetic strain rate data; earthquake catalogs through 2012 that include new assessments of locations and magnitudes; earthquake adaptive smoothing models that more fully account for the spatial clustering of earthquakes; and 22 ground motion models, some of which consider more than double the shaking data applied previously. Alternative input models account for larger earthquakes, more complicated ruptures, and more varied ground shaking estimates than assumed in earlier models. The ground motions, for levels applied in building codes, differ from the previous version by less than ±10% over 60% of the country, but can differ by ±50% in localized areas. The models are incorporated in insurance rates, risk assessments, and as input into the U.S. building code provisions for earthquake ground shaking.

Most studies of the geologic records of prehistoric earthquakes are driven by the need of seismic-hazard analyses for estimates of the locations, ages, and magnitudes of individual large earthquakes. In North America, most such studies analyze surface ruptures and earthquake-induced sand blows, dikes, and sills. In contrast, small, softsediment structures in one or a few beds, possibly induced by seismic shaking, are little used in North American hazard analyses. The reason is that present methods for studying such structures often cannot demonstrate an earthquake origin, rule out alternatives, or estimate location, age, and magnitude as well as can methods developed for the study of surface ruptures and sand blows, dikes, and sills. This chapter proposes six tests to distinguish seismic from nonseismic origins of small, soft-sediment structures in one or a few beds. The tests utilize evidence for sudden formation, synchroneity and zoned map distribution over many exposures, size of the structures, and tectonic and depositional settings. The main barriers to more rigorous utilization of these soft-sediment structures in hazard analysis are (1) few observations of their formation during historical earthquakes, and (2) few or no measurements of the threshold earthquake magnitudes and threshold horizontal accelerations that are required to form the structures.