Metadata: Identification_Information: Citation: Citation_Information: Originator: S.D. Ellen Originator: R.K. Mark Originator: G.F. Wieczorek Originator: C.M. Wentworth Originator: D.W. Ramsey Originator: T.E. May Publication_Date: 1997 Title: San Francisco Bay Region landslide folio part E - Map of debris-flow source areas in the San Francisco Bay region, California Geospatial_Data_Presentation_Form: map Series_Information: Series_Name: U.S. Geological Survey Open-File Report Issue_Identification: 97-0745-E Other_Citation_Details: ARC/INFO vector COVERAGE format (less than 1MB for entire region) and raster GRID format (4.3MB). Plotfiles in PostScript also available. Online_Linkage: http://pubs.usgs.gov/of/1997/of97-745/of97-745e.html Description: Abstract: This map identifies the principal areas in the San Francisco Bay region that are likely to produce debris flows, which are also called "mudslides." Debris flows that occur in the bay region are fast-moving downslope flows of mud that may include rocks, vegetation, and other debris. These flows begin during intense rainfall as shallow landslides on steep slopes. The rapid movement and sudden arrival of debris flows pose a hazard to life and property during and immediately following the triggering rainfall. Debris flows in a given storm originate from a number of sources scattered throughout steep parts of the landscape, as shown in figure 1 (on map sheet; files sfbr- df.ps, al-df.ps, etc.). During subsequent storms, new debris flows originate from different sources. These various sources, however, are similar in topographic form because debris-flow initiation requires steep slopes and prefers concave parts of hillsides. Purpose: These topographic characteristics are used to predict the likely future source areas shown on this map. Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1997 Currentness_Reference: publication date Status: Progress: Complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -123.678 East_Bounding_Coordinate: -120.975 North_Bounding_Coordinate: 38.888 South_Bounding_Coordinate: 36.85 Keywords: Theme: Theme_Keyword_Thesaurus: USGS Thesaurus Theme_Keyword: geology Theme_Keyword: geologic maps Theme_Keyword: landslides Theme_Keyword: surficial geologic units Theme_Keyword: geologic history Theme_Keyword: geospatial datasets Theme: Theme_Keyword_Thesaurus: National Geologic Map Database Catalog themes, augmented Theme_Keyword: 3400 - Graphical Theme_Keyword: 3100 - Vector Theme_Keyword: 3420 - PostScript Theme_Keyword: 3110 - ESRI Theme_Keyword: 3111 - coverage Theme_Keyword: 3200 - Raster Theme_Keyword: 1500 - Hazards Theme_Keyword: 1503 - Landslides Theme_Keyword: 3220 - Grid Theme: Theme_Keyword_Thesaurus: ISO 19115 Topic Categories Theme_Keyword: geoscientificInformation Place: Place_Keyword_Thesaurus: Augmented FIPS 10-4 and FIPS 6-4 Place_Keyword: f06001 = Alameda Place_Keyword: f06013 = Contra Costa Place_Keyword: f06041 = Marin Place_Keyword: f06055 = Napa Place_Keyword: f06085 = Santa Clara Place_Keyword: f06087 = Santa Cruz Place_Keyword: f06075 = San Francisco Place_Keyword: f06081 = San Mateo Place_Keyword: f06095 = Solano Place_Keyword: f06097 = Sonoma Access_Constraints: none Use_Constraints: none Point_of_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Graymer, Russell W Contact_Organization: USGS-GEO-WRG-NGM Contact_Address: Address_Type: mailing and physical address Address: Mail Stop 975, USGS 345 Middlefield Road City: Menlo Park State_or_Province: CA Postal_Code: 94025 Country: US Contact_Voice_Telephone: 650-329-4988 Contact_Electronic_Mail_Address: rgraymer@usgs.gov Browse_Graphic: Browse_Graphic_File_Name: http://pubs.usgs.gov/of/1997/of97-745/view.html Browse_Graphic_File_Description: PDF representation of debris-flow map sorted by county Browse_Graphic_File_Type: PDF Data_Set_Credit: The predicted debris-flow source areas were determined by Ellen and Mark by analysis of detailed mapping (Wentworth, 1986; Ellen, Cannon, and Reneau, 1988) that was meticulously digitized by Ramsey and May. The mapped debris-flow sources triggered by the 1982 storm were digitized by Wieczorek and Mark from mapping documented in Ellen and Wieczorek (1988); the boundary of this mapping was digitized by Beukelman. The shaded-relief topographic base was created by Graham using relations provided by R.A. Haugerud. Native_Data_Set_Environment: ARC/INFO version 7.0.4 Data_Quality_Information: Logical_Consistency_Report: The map was produced using a Geographic Information System (GIS) from a 30-meter-square grid of topographic elevations in the region. The grid of elevations, called a digital elevation model (DEM), permits calculation of hillslope steepness and curvature for each 30-m cell. The potential debris-flow sources shown on the map were determined using the values of steepness and curvature defined in table 1. Table 1 - Hillslope steepness and curvature used to map potential debris-flow source areas [Values as measured on 30-m elevation grids. Plan curvature is curvature of the ground surface in a horizontal plane; it is measured as 1/r, where r is radius of curvature in meters and negative values indicate concave areas such as swales. Hillslope steepness is dominant in determining potential source areas of the map; plan curvature excludes only 6.5 percent of hillslopes 20 degrees and steeper] >Hillslope steepness Plan curvature >20 degrees and greater +0.01 and less (including all negative > values) Completeness_Report: Substantially complete Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: The locations of many of these mapped sources may be inaccurate because of the sparse (200 ft) topographic contours present in the 1:62,500-scale base maps, which previously had been enlarged from 1:125,000-scale materials. Lineage: Process_Step: Process_Description: The map was produced using a Geographic Information System (GIS) from a 30- meter-square grid of topographic elevations in the region. The grid of elevations, called a digital elevation model (DEM), permits calculation of hillslope steepness and curvature for each 30-m cell. The potential debris-flow sources shown on the map were determined using the values of steepness and curvature defined in table 1. The parameters in table 1 were determined from values of steepness and curvature at mapped sources of historical debris flows in two calibration areas, one near Montara Mountain in San Mateo County (Wentworth, 1986) and one in Marin County (plate 6 of Ellen, Cannon, and Reneau, 1988). Typical plots describing these measures are shown in figure 2. The values in table 1 were selected by eye from four sets of such plots (two different types of geologic materials in each of the two calibration areas), with the aim of including most of the range of values associated with the mapped sources. Specifically, we used the values where the "sources" curves (fig. 2) attained 50 percent of their maximum value and where the "ratio" curves attained about 50 percent of the value at which they reach a crude plateau. In the meticulously mapped calibration areas, the red zones defined by table 1 include 82 percent of the mapped debris-flow sources. In the bay region as a whole, only 53 percent of the black dots of the map lie within the red zones. This low percentage probably results at least in part from inaccurate location of the black dots due to small-scale base maps used for some of the region-wide mapping. Process_Date: 1988-1997 Process_Step: Process_Description: Creation of original metadata record Process_Date: 20000731 Process_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Jennifer Lenz Contact_Organization: US Geological Survey Contact_Address: Address_Type: mailing Address: 12201 Surise Valley Drive, Mail Stop 918 City: Reston State_or_Province: VA Postal_Code: 20192 Country: USA Contact_Voice_Telephone: 703-648-6974 Contact_Facsimile_Telephone: 703-648-6560 Contact_Electronic_Mail_Address: pschweitzer@usgs.gov Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: vector Point_and_Vector_Object_Information: SDTS_Terms_Description: SDTS_Point_and_Vector_Object_Type: Entity Point SDTS_Terms_Description: SDTS_Point_and_Vector_Object_Type: Complete Chain Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Planar: Grid_Coordinate_System: Grid_Coordinate_System_Name: Universal Transverse Mercator Universal_Transverse_Mercator: UTM_Zone_Number: 10 Transverse_Mercator: Scale_Factor_at_Central_Meridian: 0.9996 Longitude_of_Central_Meridian: -123 Latitude_of_Projection_Origin: 0.0 False_Easting: 500000 False_Northing: 0 Planar_Coordinate_Information: Planar_Coordinate_Encoding_Method: coordinate pair Planar_Distance_Units: meters Geodetic_Model: Horizontal_Datum_Name: North American Datum of 1927 Ellipsoid_Name: Clarke 1866 Semi-major_Axis: 6378206 Denominator_of_Flattening_Ratio: 294.98 Entity_and_Attribute_Information: Detailed_Description: Entity_Type: Entity_Type_Label: SFBR-DFS.PAT Entity_Type_Definition: Mapped 1982 debris-flow sources (contains unique attribute identifications, but none are clear or explained in pamphlet. Entity_Type_Definition_Source: OFR-97-0745-E Detailed_Description: Entity_Type: Entity_Type_Label: SFBR-DMFL.AAT Entity_Type_Definition: Boundary of mapping of 1982 sources Entity_Type_Definition_Source: OFR-97-0745-E Distribution_Information: Distributor: Contact_Information: Contact_Organization_Primary: Contact_Organization: USGS Information Services Contact_Address: Address_Type: mailing Address: Box 25286, Denver Federal Center City: Denver State_or_Province: Colorado Postal_Code: 80255-0046 Country: USA Contact_Voice_Telephone: 1-888-ASK-USGS Contact_Facsimile_Telephone: 1-303-202-4695 Contact_Electronic_Mail_Address: infoservices@usgs.gov Resource_Description: US Geological Survey Open-File Report 97-0745-E Distribution_Liability: This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. This database, identified as "Map Showing Principal Debris-Flow Source Areas in the San Francisco Bay Region, California,"has been approved for release and publication by the Director of the USGS. Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use. Standard_Order_Process: Digital_Form: Digital_Transfer_Information: Format_Name: ARCE File_Decompression_Technique: gzip -d Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: http://pubs.usgs.gov/of/1997/of97-745/sfbr-dfs.e00.gz Network_Resource_Name: http://pubs.usgs.gov/of/1997/of97-745/sfbr-dfml.e00.gz Digital_Form: Digital_Transfer_Information: Format_Name: ArcInfo Grid File_Decompression_Technique: gzip -d and tar Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: http://pubs.usgs.gov/of/1997/of97-745/sfbr-df.tar.gz Fees: none Metadata_Reference_Information: Metadata_Date: 20160205 Metadata_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Peter N Schweitzer Contact_Organization: USGS Midwest Area Contact_Position: Collection manager, USGS Geoscience Data Clearinghouse, http://geo-nsdi.er.usgs.gov/ Contact_Address: Address_Type: mailing address Address: Mail Stop 954 12201 Sunrise Valley Dr City: Reston State_or_Province: VA Postal_Code: 20192-0002 Country: USA Contact_Voice_Telephone: 703-648-6533 Contact_Facsimile_Telephone: 703-648-6252 Contact_Electronic_Mail_Address: pschweitzer@usgs.gov Metadata_Standard_Name: Content for Digital Geospatial Metadata Metadata_Standard_Version: FGDC-STD-001-1998