Description: Geologists excavate trenches across faults to determine more detailed information about earthquake history on the fault. Information from this type of study includes the direction of fault movement, the number and timing of earthquakes, and the recurrence interval. Finding faults and knowing how often they rupture is one of the most important tasks needed to fully characterize earthquake hazards. Such information moves society towards a full enough understanding of the frequency of earthquakes in a given region to make earthquake forecasting possible.
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Description: This dataset includes reports of earthquake damage associated with the 1949 (6.7 M), 1965 (6.7 M), and 2001 (6.8 M) Puget Sound earthquakes in Washington State. Each point marks damage by type, site descriptions, the nearest city and county, source citations, and first-hand accounts and comments. Earthquake damage data were obtained from the Pacific Earthquake Engineering Research Center (PEER), United States Geological Survey (USGS), and the Washington Geological Survey (WGS).
Description: Washington has dozens of faults and fault zones with geologic evidence of movement in the Quaternary time period, of which many pose a significant hazard for Washington communities. This dataset contains geologically well-supported interpretations of Quaternary fault location, age and other parameters important for assessing seismic hazard. Another term commonly used for faults with movement during the Quaternary is "active". For the Washington Geological Survey, "active" means that a fault has evidence for movement within the Holocene time period (since about 12,000 years ago). It may also mean that small earthquakes have been documented on the fault. We include active faults in this database as well as other faults that have evidence for movement within the Quaternary time period (last 2.58 million years) or suspected movement in the Quaternary (also called class B), because they all have the potential to create damaging earthquakes sometime in the future within a timeframe that matters to humans. For most faults in Washington, there is not enough evidence of past earthquake activity to forecast the timing of future events. Throughout scientific history in Washington state, different interpretations of Quaternary faults have resulted from different mapping methods and scales of investigation. Dataset users will benefit from a full investigation of sources cited, reading other past work, and developing an understanding of the breadth of study types for any particular fault of interest. For geologic mapping, tectonic studies, and other scientific investigations, this database is best used for understanding the orientation of, connectivity between, and deformation along Washington fault networks in the present. For earthquake hazards characterization, this database is best used in reconnaisance-scale investigations, to identify regions closer or farther away from active faults in a qualitative sense, or in probabilistic seismic hazard analysis studies (PSHA) that consider the hazards that faults pose for a given area in a probabilistic sense. The WGS does not advise uses of this database that aim to quantify distance of a location of interest to a particular fault or that rely on high precision fault placement with respect to specific properties.
FAULT_AGE
(
type: esriFieldTypeString, alias: Age of Most Recent Activity, length: 255
, Coded Values:
[historic (<150 years): historic (<150 years)]
, [insufficient data to determine age (class B): insufficient data to determine age (class B)]
, [late Quaternary (<130,000 years): late Quaternary (<130,000 years)]
, ...3 more...
)
Description: Washington has dozens of rock folds with geologic evidence of deformation in the Quaternary time period. This dataset contains geologically well-supported interpretations of Quaternary fold location, age, and other parameters important for assessing seismic hazard. Folds are important for assessing seismic hazard because faults in the deep subsurface can cause folding of rocks, and folding of rocks closer to the surface can trigger movement on associated faults. Therefore, folds mark places where earthquake-generating faults may exist, but may not yet be characterized. Another term commonly used for folds with movement during the Quaternary is "active". For the Washington Geological Survey, "active" means that a fold has evidence for movement within the Holocene time period (since about 12,000 years ago). We include active folds in this database as well as other folds that have evidence for movement within the Quaternary time period (last 2.58 million years) or suspected movement in the Quaternary, because associated faults all have the potential to create a damaging earthquake sometime in the future within a time frame that matters to humans. Throughout scientific history in Washington state, different interpretations of Quaternary faults and folds have resulted from different mapping methods and scales of investigation. Dataset users will benefit from a full investigation of sources cited, other past work, and developing an understanding of the breadth of study types for any particular fold of interest. For earthquake hazards characterization, this database is best used in reconnaisance-scale investigations, to identify regions closer or further away from active faults in a qualitative sense, or in probabilistic seismic hazard analysis studies (PSHA) that consider the hazards that faults pose for a given area in a probabilistic sense. The WGS does not advise uses of this database that aim to quantify distance of a location of interest to a particular fault or rely on high precision fault placement with respect to specific properties.
Description: The Washington Geological Survey relocated earthquake hypocenters for events greater than magnitude 1.0 with depths shallower than 25 km throughout Washington State. Relocating earthquakes gives a better estimation of the three-dimensional position of the earthquake. These improvements are made by careful review of the data by a skilled analyst. The original earthquake data (P and S-wave arrival times) were obtained from the Pacific Northwest Seismic Network (PNSN) catalog and the earthquakes were relocated using the ‘hypoDD’ computer program. The hypoDD program uses a double-difference earthquake relocation algorithm of Waldhauser and Ellsworth (2000) to relocate earthquake clusters relative to one another, in some cases revealing previously unobserved linear trends. Linear trends of earthquake locations within a region can help scientists locate unmapped faults.
Description: The Washington Geological Survey compiled earthquake epicenter locations and depths for events exceeding magnitude 1.0. Included for each event are latitude and longitude coordinates, earthquake depth, an observed date and time, and an earthquake magnitude. The Pacific Northwest Seismic Network (PNSN) catalog provided the data.