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Probabilistic seismic hazard maps were prepared for Alaska portraying peak horizontal ground acceleration and horizontal spectral response acceleration for 0.2, 0.3, and 1.0 second periods with probabilities of exceedance of 10% in 50 years and 2% in 50 years. This particular data set is for peak horizontal acceleration with a 10% probability of exceedance in 50 years. All of the maps were prepared by combining hazard derived from spatially-smoothed historic seismicity with hazard from fault-specific sources. The acceleration values contoured are the random horizontal component. The reference site condition is firm rock, defined as having an average shear-wave velocity of 760 m/sec in the top 30 meters corresponding...
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The data set consists of time, depth, reflection coefficient synthetic, sonic velocity, density, and amplitude used to create synthetic seismogram - City of Hollywood Utility, G-2961, (HOL-IW1), Broward County, Florida.
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Staff from Alaska Earthquake Center, Geophysical Institute and Alaska Division of Geological & Geophysical Surveys evaluated potential tsunami hazards for the city of Sand Point, on Popof Island in the Shumagin Islands archipelago. We numerically modeled the extent of inundation from tsunami waves generated by local and distant earthquake sources. We considered the results in light of historical observations. The worst-case scenarios are defined by analyzing results of the sensitivity study of the tsunami dynamics with respect to different slip distributions along the Aleutian megathrust. For the Sand Point area, the worst-case scenarios are thought to be thrust earthquakes in the Shumagin Islands region with magnitudes...
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This data release contains processed high-resolution multichannel sparker seismic-reflection (MCS) data that were collected aboard Humboldt State University’s R/V Coral Sea in October of 2018 on U.S. Geological Survey cruise 2018-658-FA on the shelf and slope between Cape Blanco, Oregon, and Cape Mendocino, California. MCS data were collected to characterize quaternary deformation and sediment dynamics along the southern Cascadia margin.
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Subduction zones are home to the most seismically active faults on the planet. The shallow megathrust interface of subduction zones host our largest earthquakes, and are the only faults capable of M9+ ruptures. Despite these facts, our knowledge of subduction zone geometry - which likely plays a key role in determining the spatial extent and ultimately the size of subduction zone earthquakes - is incomplete. Here we calculate the three- dimensional geometries of all active global subduction zones. The resulting model - Slab2 - provides for the first time a comprehensive geometrical analysis of all known slabs in unprecedented detail. ##### This distribution includes models of three-dimensional slab geometry under...
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Seismicity catalogs, gridded seismic hazard curve data, gridded ground motion data, and mapped gridded ground motion values are available for the 2002 National Seismic Hazard Model for the Conterminous U.S. Seismicity catalogs are available for the western U.S. (in Mw) and central and eastern U.S. (in mb). Probabilistic seismic hazard data and maps of the conterminous U.S. for peak ground acceleration (PGA) and 0.1, 0.2, 0.3, 0.5, 1.0 and 2.0 second spectral acceleration at probability levels of 2 percent in 50 years (annual probability of 0.000404) and 10 percent in 50 years (annual probability of 0.0021), assuming firm rock soil conditions at 760 m/s, are available. Hazard was calculated on a 0.1 degree by 0.1...
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Gridded ground motion data and mapped gridded ground motion values are available for the 1999 Alaska Seismic Hazard Model. Probabilistic seismic hazard data and maps of Alaska and the Aleutians for peak ground acceleration (PGA) and 0.2, 0.3, and 1.0 second spectral acceleration at probability levels of 2 percent in 50 years (annual probability of 0.000404) and 10 percent in 50 years (annual probably of 0.0021), assuming firm rock soil conditions at 760 m/s, are available. Development of the 1999 Alaska Seismic Hazard Model is documented in the USGS Open-File Report 99-36 (https://doi.org/10.3133/ofr9936). This dataset is considered a legacy dataset. The original dataset was released at the time of publication...
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The 2018 KÄ«lauea eruption and caldera collapse generated intense cycles of seismicity tied to repeated large seismic (Mw ~5) collapse events associated with magma withdrawal from beneath the summit. To gain insight into the underlying dynamics and aid eruption response, we applied waveform-based earthquake detection and double-difference location as the eruption unfolded. Here, we augment these rapid results by grouping events based on patterns of correlation-derived phase polarities across the network. From April 29 to August 6, bracketing the eruption, we used ~2800 events cataloged by the Hawaiian Volcano Observatory to detect and precisely locate 44,000+ earthquakes. Resulting hypocentroids resolve complex,...
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I use template matching and precise relative relocation techniques to develop a high-resolution earthquake catalog for the initial portion of the 2019 Ridgecrest earthquake sequence, from July 4-16, encompassing the foreshock sequence and the first 10+ days of aftershocks following the Mw 7.1 mainshock. Using 13,525 routinely cataloged events as waveform templates, I detect and precisely locate a total of 34,091 events. Precisely located earthquakes reveal numerous cross-cutting fault structures with dominantly perpendicular SW- and NW-strikes. Foreshocks of the Mw 6.4 event appear to align on a NW-striking fault. Aftershocks of the Mw 6.4 event suggest that it further ruptured this NW-striking fault, as well as...
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High-resolution acoustic backscatter data, bathymetry data, single channel minisparker seismic-reflection data were collected by the U.S. Geological Survey (USGS) and the Alaska Department of Fish and Game in May of 2014 southwest of Chenega Island and southwest of Montague Island, Alaska. Data were collected aboard the Alaska Department of Fish and Game vessel, R/V Solstice, during USGS field activity 2014-622-FA, using a pole mounted 100-kHz Reson 7111 multibeam echosounder, a 500 Joule SIG 2-mille minisparker sound source and a single channel streamer.
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Compressional- (P-) wave seismic refraction data were acquired in December 2018 and July 2019 along fourteen profiles within the spillway of Success Dam in Porterville, California. A new concrete ogee weir is planned for construction within the existing spillway, and the P-wave seismic velocity models will be used to inform further geotechnical investigations, including siting new geologic borings, and the advanced engineering design phases in terms of rock rippability and relative rock hardness/competency. Data acquisition, processing, and modeling were conducted collaboratively between the U.S. Geological Survey (USGS) and U.S. Army Corps of Engineers (USACE) Sacramento District. Data were acquired with Geometrics...
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Seismicity catalogs, GIS shapefiles, gridded seismic hazard curve data, gridded ground motion data, and mapped gridded ground motion values are available for the 2014 National Seismic Hazard Model for the Conterminous U.S. Probabilistic seismic hazard data and maps of the conterminous U.S. for peak ground acceleration (PGA) and 0.2 and 1.0 second spectral acceleration at probability levels of 2 percent in 50 years (annual probability of 0.000404) and 10 percent in 50 years (annual probability of 0.0021), assuming firm rock soil conditions at 760 m/s, are available. Hazard was calculated on a 0.05 degree by 0.05 degree grid, defined by a bounding box encompassing the conterminous U.S. (-125 to -65 degrees longitude...
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This data release provides access to a low-altitude, aeromagnetic survey of a part of south-central Washington and north-central Oregon. The survey extends from the Blue Mountains westward to the Cascade Range and covers the Oregon cities of The Dalles, Hermiston, and Milton Freewater and the Washington cities of Richland, Pasco, Kennewick, and Walla Walla. Data were acquired during the summer of 2010 by Goldak Airborne Surveys working under contract to the U.S. Geological Survey. Total magnetic field values were acquired using a fixed-wing aircraft flown at a target elevation of 150 m above terrain (305 m over urban areas) and along flight lines and tie lines spaced 400 m and 4000 m apart, respectively. Flight...
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Multichannel minisparker and boomer seismic-reflection and chirp sub bottom data were collected by the U.S. Geological Survey in September of 2013 in Port Valdez, Alaska. Data were collected aboard the USGS R/V Alaskan Gyre during field activity G-01-13-GA. Sub-bottom acoustic penetration spans several hundreds of meters and is variable by location. High-resolution multichannel seismic-reflection data were acquired to support the U.S. Geological Survey Alaska coastal and marine hazards project to explore the sedimentary structure of tsunamigenic landslide deposits around an IODP drill site in Port Valdez. These data and information are intended for science researchers, students from elementary through college, policy...
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In March 2015, the U.S. Geological Survey acquired seismic reflection and refraction data along an approximately 2.8-km-long profile across northwest-trending San Andreas Fault splays located at the Dos Palmas Preserve east of Salton Sea. To acquire the reflection and refraction data, we collocated shots and geophones, spaced every 3 m along the profile. We used 933 SercelTM L40A P-wave (40-Hz vertical-component) geophones with a sensitivity of 22.34 volts/meter/second to record 925 P-wave shots. We generated P-wave data using one of two active sources: 400-grain Betsy-SeisgunTM shots at approximately every 90 m and a 3.5-kg sledgehammer and steel plate combination at every 3 m between the seisgun shots. All data...
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ShakeMap is a product of the USGS Earthquake Hazards Program in conjunction with the regional seismic networks. ShakeMaps provide near-real-time maps of ground motion and shaking intensity following significant earthquakes. These maps are used by federal, state, and local organizations, both public and private, for post-earthquake response and recovery, public and scientific information, as well as for preparedness exercises and disaster planning.
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New active-source shallow seismic (shear-wave and acoustic-wave) measurements were obtained at 18 prioritized seismic monitoring station locations in the north San Francisco Bay area to measure site-specific ground motion amplification effects, soil depth, depth to bedrock (Z1.0 Vs=1 km/s), calculate site specific velocity-depth profiles and Vs30, and develop NEHRP site classifications for each location. This study was led by Principal Investigators Jamey Turner, Cooper Brossy, and Daniel O’Connell and field data were acquired by Glendon Adams and Lincoln Steele. Seismic monitoring sites that recorded high PGA values during the M6.0 Napa earthquake, proximal to higher population densities, and sites recommended...


map background search result map search result map Seismic-Hazard Maps for Alaska and the Aleutian Islands: PGA050 G-2946 : Synthetic Seismogram Data for Correlation Between Seismic-Reflection Profiles and Well Data, Broward County, Florida G-2961 (HOL-IW1) : Synthetic Seismogram Data for Correlation Between Seismic-Reflection Profiles and Well Data, Broward County, Florida Tsunami inundation maps for the city of Sand Point, Alaska 2015 high resolution seismic acquisition at Dos Palmas Preserve, Mecca, California Velocity models and first break picks, Success Dam spillway seismic refraction survey, Porterville, California Data Release for the 2002 National Seismic Hazard Model for the Conterminous U.S. Data Release for the 2014 National Seismic Hazard Model for the Conterminous U.S. High resolution earthquake catalogs from the 2018 Kilauea eruption sequence Multichannel sparker seismic reflection data of USGS field activity 2018-658-FA collected between Cape Blanco and Cape Mendocino from 2018-10-04 to 2018-10-18 High-Resolution Aeromagnetic Survey of the Pasco Area, Washington and Oregon Chirp, multichannel minisparker, and boomer seismic-reflection data from USGS field activity G-01-13-GA collected in Port Valdez, Alaska, in September 2013 Velocity models and first break picks, Success Dam spillway seismic refraction survey, Porterville, California 2015 high resolution seismic acquisition at Dos Palmas Preserve, Mecca, California High resolution earthquake catalogs from the 2018 Kilauea eruption sequence Tsunami inundation maps for the city of Sand Point, Alaska G-2946 : Synthetic Seismogram Data for Correlation Between Seismic-Reflection Profiles and Well Data, Broward County, Florida G-2961 (HOL-IW1) : Synthetic Seismogram Data for Correlation Between Seismic-Reflection Profiles and Well Data, Broward County, Florida High-Resolution Aeromagnetic Survey of the Pasco Area, Washington and Oregon Multichannel sparker seismic reflection data of USGS field activity 2018-658-FA collected between Cape Blanco and Cape Mendocino from 2018-10-04 to 2018-10-18 Data Release for the 2002 National Seismic Hazard Model for the Conterminous U.S. Data Release for the 2014 National Seismic Hazard Model for the Conterminous U.S. Seismic-Hazard Maps for Alaska and the Aleutian Islands: PGA050