Description: <DIV STYLE="text-align:Left;font-size:12pt"><DIV><DIV><P><SPAN>Gravitational geophysical surveys are carried out to understand density properties of subsurface rocks. Scientists can interpret variations in very precise measurements of Earth's gravity from place to place across the surface of the Earth in terms of corresponding changes in rock density within the subsurface. Geophysicists work with geologists to relate these density changes to known rock types in the area and thus provide constraint on models of the subsurface (for example, geologic cross-sections).</SPAN></P></DIV></DIV></DIV>
Description: <DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN><SPAN>Gravitational geophysical surveys are carried out to understand density properties of subsurface rocks. Scientists can interpret variations in very precise measurements of Earth's gravity from place to place across the surface of the Earth in terms of corresponding changes in rock density within the subsurface. Geophysicists work with geologists to relate these density changes to known rock types in the area and thus provide constraint on models of the subsurface (for example, geologic cross-sections). A gravity station is a point where a gravity measurement was made on the Earth's surface.</SPAN></SPAN></P></DIV></DIV></DIV>
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Description: <DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN><SPAN>Gravitational geophysical surveys are carried out to understand density properties of subsurface rocks. Scientists can interpret variations in very precise measurements of Earth's gravity from place to place across the surface of the Earth in terms of corresponding changes in rock density within the subsurface. Geophysicists work with geologists to relate these density changes to known rock types in the area and thus provide constraint on models of the subsurface (for example, geologic cross-sections). A gravity profile is made up of individual gravity point measurements that are usually displayed as a line graph which indicates changes in gravity over a horizontal distance.</SPAN></SPAN></P></DIV></DIV></DIV>
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Description: <DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN>Gravitational geophysical surveys are carried out to understand density properties of subsurface rocks. Scientists can interpret variations in very precise measurements of Earth's gravity from place to place across the surface of the Earth in terms of corresponding changes in rock density within the subsurface. Geophysicists work with geologists to relate these density changes to known rock types in the area and thus provide constraint on models of the subsurface (for example, geologic cross-sections). A gravity anomaly map shows changes in gravity over both latitude and longitude. It is usually created via a mathematical gridding algorithm from individual point data. This map may exist within the greater extent of a project area.</SPAN></P></DIV></DIV></DIV>
Description: <DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN>A gravity base station is a point on Earth's surface where the absolute value of gravity is well known. Gravity base stations are established to tie relative gravity measurements to an accepted gravity value that has been determined through the use of an absolute gravimeter, or repeated relative measurements to another established base station. They are sometimes also used to measure changes in Earth's gravity over time. Scientists can use repeated measurements at established gravity base stations during the course of a relative gravity survey to determine, account for, and remove instrument drift from relative gravity measurements. </SPAN></P></DIV></DIV></DIV>
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Description: <DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN>Gravitational geophysical surveys are carried out to understand density properties of subsurface rocks. Scientists can interpret variations in very precise measurements of Earth's gravity from place to place across the surface of the Earth in terms of corresponding changes in rock density within the subsurface. Geophysicists work with geologists to relate these density changes to known rock types in the area and thus provide constraint on models of the subsurface (for example, geologic cross-sections). A gravity station is a point where a gravity measurement was made on the Earth's surface.</SPAN></P></DIV></DIV></DIV>
Color: [0, 0, 0, 255] Background Color: N/A Outline Color: N/A Vertical Alignment: bottom Horizontal Alignment: left Right to Left: false Angle: 0 XOffset: 0 YOffset: 0 Size: 10 Font Family: Tahoma Font Style: normal Font Weight: normal Font Decoration: none
Description: <DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN>A gravity base station is a point on Earth's surface where the absolute value of gravity is well known. Gravity base stations are established to tie relative gravity measurements to an accepted gravity value that has been determined through the use of an absolute gravimeter, or repeated relative measurements to another established base station. They are sometimes also used to measure changes in Earth's gravity over time. Scientists can use repeated measurements at established gravity base stations during the course of a relative gravity survey to determine, account for, and remove instrument drift from relative gravity measurements. </SPAN></P></DIV></DIV></DIV>
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Description: <DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN><SPAN>A project location is the geographical extent of the study area of interest. Multiple types of surveys and data types may be included within these areas. This feature class serves to join data-oriented feature class entries for a single project and provide a citation.</SPAN></SPAN></P></DIV></DIV></DIV>
Description: <DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN>This grid layer displays the complete Bouguer gravity anomaly (in mGals) for the state of Washington. The dataset used to create this grid layer was obtained through the GeoNet Gravity Dataset Repository that was developed by the Pan American Center for Earth & Environmental Studies (PACES). In 2003, PACES in cooperation with the U.S. Geological Survey (USGS), the National Geospatial-Intelligence Agency, National Oceanic and Atmospheric Administration (NOAA), and colleagues from industry and academia completed a compilation of gravity data throughout North America to develop the GeoNet Gravity Dataset Repository. The data incorporated into this database was originally derived from a variety of sources including the National Geospatial Agency (NGA), National Geodetic Survey (NGS), Defense Mapping Agency (DMA), and the USGS. Funding for this data compilation was provided through a U.S. Department of Energy geothermal grant. As of 2023, the database is obsolete and no longer maintained by PACES, though copies of the data reside with various researchers across the U.S.</SPAN></P></DIV></DIV></DIV>
Description: <DIV STYLE="text-align:Left;"><DIV><DIV STYLE="font-size:12pt"><P><SPAN>Magnetic geophysical surveys are carried out to understand magnetic properties of subsurface rocks. Scientists can interpret variations in measurements of Earth's magnetic field from place to place across the surface of the Earth in terms of corresponding changes in rock magnetism within the subsurface. Geophysicists work with geologists to relate these magnetic changes to known rock types in the area and thus provide constraint on models of the subsurface (for example, geologic cross-sections).</SPAN></P></DIV></DIV></DIV>
Description: <DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN><SPAN>Magnetic geophysical surveys are carried out to understand magnetic properties of subsurface rocks. Scientists can interpret variations in measurements of Earth's magnetic field from place to place across the surface of the Earth in terms of corresponding changes in rock magnetism within the subsurface. Geophysicists work with geologists to relate these magnetic changes to known rock types in the area and thus provide constraint on models of the subsurface (for example, geologic cross-sections). A magnetic point is a place where a magnetic measurement was made on the Earth's surface.</SPAN></SPAN></P></DIV></DIV></DIV>
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Description: <DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN><SPAN>Magnetic geophysical surveys are carried out to understand magnetic properties of subsurface rocks. Scientists can interpret variations in measurements of Earth's magnetic field from place to place across the surface of the Earth in terms of corresponding changes in rock magnetism within the subsurface. Geophysicists work with geologists to relate these magnetic changes to known rock types in the area and thus provide constraint on models of the subsurface (for example, geologic cross-sections). A magnetic profile is made up of individual point measurements that are usually displayed as a line graph that indicates changes in the Earth's magnetic field over a horizontal distance.</SPAN></SPAN></P></DIV></DIV></DIV>
Color: [0, 0, 0, 255] Background Color: N/A Outline Color: N/A Vertical Alignment: bottom Horizontal Alignment: left Right to Left: false Angle: 0 XOffset: 0 YOffset: 0 Size: 10 Font Family: Tahoma Font Style: normal Font Weight: normal Font Decoration: none
Description: <DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN><SPAN>Magnetic geophysical surveys are carried out to understand magnetic properties of subsurface rocks. Scientists can interpret variations in measurements of Earth's magnetic field from place to place across the surface of the Earth in terms of corresponding changes in rock magnetism within the subsurface. Geophysicists work with geologists to relate these magnetic changes to known rock types in the area and thus provide constraint on models of the subsurface (for example, geologic cross-sections). A magnetic anomaly map shows changes in earth's magnetism over both latitude and longitude. These variations in the local magnetic field can be attributed to changes in lithology over an area. The map is usually created via mathematical gridding algorithm from individual point or profile data. This map may exist within the greater extent of a project area. </SPAN></SPAN></P></DIV></DIV></DIV>
Description: <DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN><SPAN>A project location is the geographical extent of the study area of interest. Multiple types of surveys and data types may be included within these areas. This feature class serves to join data-oriented feature class entries for a single project and provide a citation.</SPAN></SPAN></P></DIV></DIV></DIV>
Description: <DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN>This grid layer displays aeromagnetic anomaly data (in nT) for the state of Washington. The dataset used to create this grid layer was obtained through the GeoNet Magnetic Data Repository that was developed and maintained by the Pan American Center for Earth & Environmental Studies (PACES), but this service and database is no longer available. The data incorporated into the GeoNet magnetic database was derived from the North American Magnetic Map (Open-File Report 02-414) compiled by the U.S. Geological Survey (USGS) in cooperation with the Geological Survey of Canada and Consejo de Recursos Minerales of Mexico. The original data for the state of Washington used for the North American Magnetic Map compilation came from numerous sources which can be found in USGS Open-File Report 98-241. Funding for this data compilation was provided through a U.S. Department of Energy geothermal grant.</SPAN></P></DIV></DIV></DIV>
Description: <DIV STYLE="text-align:Left;"><DIV><DIV STYLE="font-size:12pt"><P><SPAN>Seismic profiles may be computed using a source for seismic energy that is generated by the researcher (termed "active seismic") or seismic energy generated by natural or man-made sources in the environment (termed "passive seismic"). Active seismic profiles are computed using the time it takes for the generated wave to reach deployed seismometers (commonly geophones). Passive seismic profiles are computed using techniques that do not necessarily require a source location. What the profile looks like and the information it shows depends on the processing applied to the data. Seismic reflection profiles process body waves, which travel down to boundaries in the earth between rocks with different seismic velocities (such as a contact between sedimentary layers) where it is reflected back and a two way travel time is recorded. These data are processed to show the depth to multiple boundaries across the profile. Seismic refraction profiles process direct and head waves, where the head wave path is approximately horizontal and travels along the interface of two beds, before refracting back to the seismometers. The resulting seismic profile gives basic information about layer thicknesses and velocities, particularly for the upper-most layers in the subsurface. Tomography is applied to body waves or surface waves and is a direct inversion of the travel time data for seismic velocities below the profile. The result is a 2-D cross-section of seismic velocities in the earth.</SPAN></P></DIV></DIV></DIV>
Description: <DIV STYLE="text-align:Left;"><P><SPAN><SPAN>Seismic profiles may be computed using a source for seismic energy that is generated by the researcher (termed "active seismic") or seismic energy generated by natural or man-made sources in the environment (termed "passive seismic"). Active seismic profiles are computed using the time it takes for the generated wave to reach deployed seismometers (commonly geophones). Passive seismic profiles are computed using techniques that do not necessarily require a source location. What the profile looks like and the information it shows depends on the processing applied to the data. Seismic reflection profiles process body waves, which travel down to boundaries in the earth between rocks with different seismic velocities (such as a contact between sedimentary layers) where it is reflected back and a two way travel time is recorded. These data are processed to show the depth to multiple boundaries across the profile. Seismic refraction profiles process direct and head waves, where the head wave path is approximately horizontal and travels along the interface of two beds, before refracting back to the seismometers. The resulting seismic profile gives basic information about layer thicknesses and velocities, particularly for the upper-most layers in the subsurface. Tomography is applied to body waves or surface waves and is a direct inversion of the travel time data for seismic velocities below the profile. The result is a 2-D cross-section of seismic velocities in the earth.</SPAN></SPAN></P></DIV>
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Description: <DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN><SPAN>A project location is the geographical extent of the study area of interest. Multiple types of surveys and data types may be included within these areas. This feature class serves to join data-oriented feature class entries for a single project and provide a citation.</SPAN></SPAN></P></DIV></DIV></DIV>
Description: <DIV STYLE="text-align:Left;"><DIV><DIV STYLE="font-size:12pt"><P><SPAN>Ground penetrating radar profiles are created by dragging a radio antenna and receiver across the ground. The antenna emits polarized electromagnetic waves downward that reflect on boundaries within the earth that separate rocks with different electrical conductivity or dielectric permittivity within the subsurface. The reflected wave is recorded by the antenna, which generates a two-way travel time. These data are processed to show the depth to multiple boundaries across the profile. The processing is similar to seismic reflection processing and the resulting profile also has a similar look but may show different boundaries. It is a particularly good method to image the very near-surface (upper 10 m).</SPAN></P></DIV></DIV></DIV>
Description: <DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN><SPAN>Ground penetrating radar profiles are created by dragging a radio antenna and receiver across the ground. The antenna emits polarized electromagnetic waves downward that reflect on boundaries within the earth that separate rocks with different electrical conductivity or dielectric permittivity within the subsurface. The reflected wave is recorded by the antenna, which generates a two-way travel time. These data are processed to show the depth to multiple boundaries across the profile. The processing is similar to seismic reflection processing and the resulting profile also has a similar look but may show different boundaries. It is a particularly good method to image the very near-surface (upper 10 m).</SPAN></SPAN></P></DIV></DIV></DIV>
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Description: <DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN><SPAN>A project location is the geographical extent of the study area of interest. Multiple types of surveys and data types may be included within these areas. This feature class serves to join data-oriented feature class entries for a single project and provide a citation.</SPAN></SPAN></P></DIV></DIV></DIV>
Description: <DIV STYLE="text-align:Left;"><DIV><DIV STYLE="font-size:12pt"><P><SPAN>Electrical geophysical surveys are carried out to understand electrical properties of subsurface rocks. Electrical profiles are generally classified into controlled source and naturally occurring electrical energy source. Controlled source survey examples include Induced Polarization (IP) and Electrical Resistivity Imagining (ERI). Naturally occurring electrical energy source survey examples include Magnetotellurics (MT) and Spontaneous Potential (SP). Modern electrical profiles are made up of multiple measurements that are processed, usually using a tomographic mathematical method, and displayed as a resistivity section.</SPAN></P></DIV></DIV></DIV>
Description: <DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN><SPAN>Electrical geophysical surveys are carried out to understand electrical properties of subsurface rocks. Electrical profiles are generally classified into controlled source and naturally occurring electrical energy source. Controlled source survey examples include Induced Polarization (IP) and Electrical Resistivity Imagining (ERI). Naturally occurring electrical energy source survey examples include Magnetotellurics (MT) and Spontaneous Potential (SP). Modern electrical profiles are made up of multiple measurements that are processed, usually using a tomographic mathematical method, and displayed as a resistivity section.</SPAN></SPAN></P></DIV></DIV></DIV>
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Description: <DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN><SPAN>A project location is the geographical extent of the study area of interest. Multiple types of surveys and data types may be included within these areas. This feature class serves to join data-oriented feature class entries for a single project and provide a citation.</SPAN></SPAN></P></DIV></DIV></DIV>