Patricia A. McCrory, James Luke Blair November, 2003 Unknown First vector digital data Data Series 91 USGS Information Services, Box 25286, Denver Federal Center, Denver, CO, 80225 United States Geological Survey http://pubs.usgs.gov/ds/91/ United States Geological Survey, Earthquake Hazards Team, November, 2003 Unknown First http://geopubs.wr.usgs.gov/*****/ slab_contours_GCS_wgs84 DEPTH TO THE JUAN DE FUCA SLAB BENEATH THE CASCADIA SUBDUCTION MARGIN: A 3D MODEL FOR SORTING EARTHQUAKES By P. A. McCrory, J. L. Blair, D. H. Oppenheimer, and S. R. Walter 2003, Version 1.0 OVERVIEW OF THE SLAB-GRID PROJECT We present an updated model of the Juan de Fuca slab beneath southern British Columbia, Washington, Oregon, and northern California, and use this model to separate earthquakes occurring above and below the slab surface. The model is based on depth contours previously published by Flück and others (1997). Our model attempts to rectify a number of shortcomings in the original model and update it with new work. The most significant improvements include 1) a gridded slab surface in geo-referenced (ArcGIS) format, 2) continuation of the slab surface to its full northern and southern edges, 3) extension of the slab surface from 50-km depth down to 110-km, beneath the Cascade arc volcanoes, and 4) revision of the slab shape based on new seismic reflection and seismic refraction studies. We have used this surface to sort earthquakes, and present some general observations and interpretations of seismicity patterns revealed by our analysis. In addition, we provide files of earthquakes above and below the slab surface, and a 3D animation or fly-through showing a shaded relief map with plate boundaries, the slab surface, and hypocenters for use as a visualization tool. We present an updated model of the Juan de Fuca slab beneath southern British Columbia, Washington, Oregon, and northern California, and use this model to separate earthquakes occurring above and below the slab surface. These data are intended for science researchers, students, policy makers, and the general public. The data can be used with geographic information systems (GIS) software to display geologic and seismic information about the pacific northwest subduction complex. en November, 2003 publication date Complete None planned -128.389527 -120.707570 51.649855 38.987363 -128.389527 -120.707570 51.649855 38.987363 45 -150 km Thesaurus of Geological terms subduction hypocenter Thesaurus of Geological terms Juan De Fuca Pacific Northwest Cascades DISCLAIMERS This Compact Disc Read-Only Memory (CD-ROM) publication was prepared by an agency of the U.S. Government. Neither the U.S. Government nor any agency thereof, nor any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed in this report, or represents that its use would not infringe on privately owned rights. Reference therein to any specific commercial product, process, or service, by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the U.S. Government or any agency thereof. Although all data and software published on this CD-ROM have been used by the U.S. Geological Survey (USGS), no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and related materials and (or) the functioning of the software. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of this data, software, or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Please recognize the U.S. Geological Survey (USGS) as the source of this information. Although these data have been used by the U.S. Geological Survey, U.S. Department of the Interior, no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of this data, software, or related materials. This information is not intended for navigational purposes. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. James Luke Blair USGS Manager, Menlo Park Earthquake Hazards Geographic Information Systems laboratory 650-329-4707 650-329-5163 lblair@usgs.gov 9-5 PST Unclassified Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 9.0.0.535 Shapefile This contour of the Juan de Fuca slab surface was constructed after the consideration of multiple resources of data. This contour data is only an interpretation by the authors of what is likely a very complex system. No degree of error was calculated in this report. This contour of the Juan de Fuca surface was constructed after the consideration of multiple resources of data. This contour data is only an interpretation by the authors of what is likely a very complex system. No degree of error was calculated in this report. The model is based on depth contours previously published by Flück and others (1997). Our model attempts to rectify a number of shortcomings in the original model and update it with new work. Contours of the slab surface were constructed after consideration of hypocenter locations, work by Flück and others (1997), and other publications listed here. After Contours were created, the ArcInfo Workstation command TOPOGRID was used to construct a Grid of the slab surface. October 2003 James Luke Blair USGS Earthquake Hazards, Mail Stop 977, Menlo Park, CA 94025 Manager, GIS lab 650-329-4707 lblair@usgs.gov 9-5 pst 20031110 ArcInfo workstation 8.3 13144800 Metadata imported. 20050207 14353200 Metadata imported.2005020715421900 Vector Grid Cell 287 184 1 1 32 FALSE Default matrix values ESRI GRID Upper Left TRUE 0.044946 0.044946 Decimal degrees 0.0000000.000000 D_WGS_1984 WGS_1984 6378137.000000 298.257224 GCS_WGS_1984 slab_contours_GCS_wgs84 17 Feature Class FIDFIDOID400Internal feature number.ESRISequential unique whole numbers that are automatically generated.ShapeShapeGeometry000Feature geometry.ESRICoordinates defining the features.ElevationElevationNumber1911Depth to slab surface in KM below sea level A contour of the surface of the subducting Juan de Fuca plate beneath the pacific northwest of the USA. Data is compiled and released on CD. 0.032 0.032 20050207 James Luke Blair USGS, Earthquake hazards team GIS lab manager USGS office

345 Middlefield Rd, mail stop 977,

menlo park ca 94025 usa 650-329-4707 lblair@usgs.gov FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998 local time en http://www.esri.com/metadata/esriprof80.htmlESRI Metadata Profile Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 9.0.0.535 -128.389527 -120.70757 51.649855 38.987363 1 slab_contours_GCS_wgs84 -128.389527 51.649855 38.987363 -120.70757 1 002 Local Area Network file://\\BANANA\E$\temp\final2\binary\gis_data\slab_contours_GCS_wgs84.shp 0.032 Shapefile 20050207 20050207 15514400 20050207 FALSE 15450400 15421900 {42530A06-92FA-440F-8DE2-814D876070C3} 20050207 dataset ISO 19115 Geographic Information - Metadata DIS_ESRI1.0 GCS_WGS_1984 17 2 1 0.044946 Degree 184 0.044946 Degree 287