Relative liquefaction susceptibility of Monterey County, California

Rosenberg, Lewis I. 2001 Relative liquefaction susceptibility of Monterey County, California version 1.0 vector digital data withheld County of Monterey 2001 21st Century General Plan Update http://www.co.monterey.ca.us/gpu Liquefaction A common type of ground failure associated with moderate and large earthquakes is liquefaction in which water-saturated fine-grained cohesionless sediments lose strength and may fail during strong ground shaking. Liquefaction susceptibility depends on the age and type of material, relative density of the material, and the depth to first (shallowest) water. Generally, younger sediments (especially latest Holocene that are less than 1,000 years old) such as loose fill, river channel, and flood plain deposits are more likely to liquefy than older Pleistocene terrace deposits. Relative liquefaction susceptibility was evaluated using a simplified version of the methodology developed for the Monterey Bay area by the USGS (Dupré and Tinsley, 1980; Dupré, 1990; Pike and others, 1994). The resulting data set shows that the areas of highest susceptibility include the Salinas, Carmel, San Antonio, and Peachtree Valleys. This map depicts the relative liquefaction susceptibility of sediments in Monterey County. The purpose of this map is to provide a comparison of relative liquefaction susceptibility for regional planning studies in Monterey County. en 2001 publication date In work Irregular -121.991705 -120.213947 36.943886 35.758422 5687177.500000 6201605.500000 1808592.500000 2229048.000000 None earthquakes liquefaction geologic hazards ground failure None Aromas Arroyo Seco Big Sur Bolsa Knolls Bradley Cachagua California Carmel Highlands Carmel Valley Carmel Valley Village Carmel-By-The-Sea Castroville Del Rey Oaks Gonzales Greenfield Jamesburg Jolon King City Lockwood Lucia Marina Monterey Monterey County Moss Landing Pacific Grove Pajaro Parkfield Pebble Beach Prunedale Salinas Salinas Valley San Ardo San Lucas Sand City Seaside Soledad Spreckels Tassajara Hot Springs United States Contact the Monterey County Environmental Resource Policy Department. These data may not be distributed without the written permission of the County of Monterey. Lew Rosenberg Consulting Geologist mailing address

P.O. Box 183

Templeton CA 93465-0183 (805) 434-1750 (805) 434-1750 Lrosenberg@thegrid.net Monday to Friday, 8 AM to 5 PM, Pacific Time ESRI ArcCatalog 9.3.1.3000 Feature Class All attributes created during the creation process were verified by displaying the lines in both the database and the spatial coverage, but no formal tests were performed. These data are believed to be logically consistent, although no tests were performed. Two main assumptions were made in creating this data set. (1) The age, ground water conditions, near-surface stratigraphy, and physical and engineering properties of the countywide Quaternary sediments were similar to their mapped counterparts in the northern part of Monterey County. (2) Systematic shallow ground water level measurements do not exist for most of Monterey County. For this study, records of the highest historical ground water levels were used in evaluating the liquefaction susceptibility. Hamlin (1904) tabulated water levels for 270 wells in the Salinas Valley from the mouth of the river southward to King City. Of these wells, most along the river had water depths of about 10 feet and the wells on the alluvial fans had water levels of 20 feet or deeper, with a median depth to water of 15 feet. However, Hamlin does not specify how many of these water levels represent artesian (confined) aquifers or shallow perched aquifers. For this study, areas of Holocene alluvium were assumed to be saturated because irrigation and dam releases into the Salinas River keep water levels shallow along the Salinas River. Although water levels have probably dropped from their historical high levels, it is conservative to assume that they may rise in the future with changes in land use, imported water, or climate. Based on these assumptions, each geologic unit in the database was assigned a high, moderate, or low liquefaction susceptibility based on age, lithologic type, depositional environment, and correlation with similar units with engineering properties that are well defined by field and laboratory testing. In summary, the Monterey County map is intended for regional planning purposes, but the relative susceptibility boundaries may change slightly with the availability of sufficient quality and quantity engineering data for Monterey County. The liquefaction data are based on information compiled from geologic maps ranging from 1:2,400 to 1:125,000 scale, with the majority at 1:62,500 scale. Using the "map resolution" concept outined by R.R. Wahl (USGS Open-File Report 99-386, p. 96: where (Map scale denominator) / 2/ 1000 = map scale, in meters), the estimated horizontal error ranges from 1.2 m (1:2,400 scale) to 62.5 m (1:125,000 scale), with a typical error of 31.3 m (1:62,500) scale. This error level reflects the accuracy of the conversion from hard copy to digital maps; however, the overall accuracy may differ if the uncertainty in each individual map used in the compilation is included. Rosenberg, Lewis I. 2001 Digital geologic map of Monterey County, California version 1.0 map County of Monterey 2001 21st Century General Plan Update http://www.co.monterey.ca.us/gpu CD-ROM 2001 publication date Rosenberg (2001) Geologic units used in liquefaction susceptiblity analysis Dupré, W.R. 1990 Maps showing geology and liquefaction susceptibility of Quaternary deposits in the Monterey, Seaside, Spreckels, and Carmel Valley quadrangles, Monterey County, California map Miscellaneous Field Studies Map 2096 U.S. Geological Survey 2 sheets 24000 paper 1990 publication date Dupré (1990) Methodology used in liquefaction susceptiblity analysis. Dupré, W.R. Tinsley, J.C., III 1980 Maps showing geology and liquefaction potential of northern Monterey and southern Santa Cruz Counties, California map Miscellaneous Field Studies Map 1199 U.S. Geological Survey 2 sheets 62500 paper 1980 publication date Dupré and Tinsley (1980) Methodology used in liquefaction susceptiblity analysis. Pike, R.J. Bernknopf, R.L. Tinsley, J.C., III Mark, R.K. 1994 Hazard of earthquake-induced lateral-spread ground failure on the central California coast modeled from earth-science map data in a geographic information system document Open-File Report 94-662 U.S. Geological Survey 46 p., 1 sheet 62500 paper 1994 Pike and others (1994) Methodology used in liquefaction susceptiblity analysis. Lithologic units on the digital geologic map (Rosenberg, 2001) were classified into four groups based on their assumed physical and engineering properties following the methodology used by by the USGS for the Monterey Bay area (Dupré and Tinsley, 1980; Dupré, 1990; Pike and others, 1994). Using ArcView software, the units were dissolved into the three groups: high, moderate, low, and variable. withheld withheld withheld withheld 20010405 Lew Rosenberg Consulting Geologist mailing address

P.O. Box 183

Templeton CA 93465-0183 (805) 434-1750 (805) 434-1750 Lrosenberg@thegrid.net Monday to Friday, 8 AM to 5 PM, Pacific Time Dataset copied. withheld Dataset copied. withheld Metadata imported. withheld 20041227 14450000 Dataset copied. withheld 20080806 12463800 Vector Simple FALSE 621 TRUE FALSE coordinate pair 0.000250 0.000250 survey feet North American Datum of 1983 Geodetic Reference System 80 6378137.000000 298.257222 GCS_North_American_1983 NAD_1983_StatePlane_California_IV_FIPS_0404_Feet 1.000000 Explicit elevation coordinate included with horizontal coordinates Liquefaction Relative liquefaction susceptibility author Feature Class 621 Shape Feature geometry. ESRI Coordinates defining the features. LIQ_SUSC String 8 0 0 LIQ_SUSC Relative liquefaction susceptibility author high area of relatively high susceptibility to liquefaction author moderate area of relatively moderate susceptibility to liquefaction author low area of relatively low susceptibility to liquefaction author variable area of variable susceptibility to liquefaction author Coordinates defining the features. Shape Geometry 4 0 0 SHAPE SHAPE.LEN Double 0 0 0 Feature geometry. ESRI Coordinates defining the features. SHAPE.LEN OBJECTID OID 4 10 0 Internal feature number. ESRI Sequential unique whole numbers that are automatically generated. OBJECTID Internal feature number. ESRI Sequential unique whole numbers that are automatically generated. SHAPE.AREA Double 0 0 0 SHAPE.AREA SHAPE.LEN Double 0 0 0 Monterey County Environmental Resource Policy Department Database Coordinator mailing address

P.O. Box 180

Salinas CA 93902 (831) 755-5353 (831) 796-3062 Monday to Friday, 8 AM to 5 PM, Pacific Time Downloadable Data This database is intended for regional planning purposes and not for site-specific evaluation. Information in this data set is preliminary in nature. This information is provided with understanding that it is not guaranteed to be correct or and conclusions drawn from such information, whether from individual use or aggregate use with other data, are the responsibility of the user. 5.718 Contact the Monterey County Environmental Resource Policy Department for a printed copy of the map or for an ESRI shapefile of the data set. For those users that do not have ArcView or ARC/INFO, ESRI provides a free GIS data viewer, ArcExplorer, that can be downloaded from their website at: http://www.esri.com/software/arcexplorer/index.html. ArcExplorer is currently only supported on the Windows 95/98 or Windows NT platforms. 20100317 20010507 Lew Rosenberg Consulting Geologist mailing address

P.O. Box 183

Templeton CA 93465-0183 (805) 434-1750 (805) 434-1750 Lrosenberg@thegrid.net Monday to Friday, 8 AM to 5 PM, Pacific Time FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998 local time http://www.esri.com/metadata/esriprof80.html ESRI Metadata Profile en 20190219 14014700 FALSE 20180410 10320500 20180410 10320500 Liquefaction 002 5687177.500000 6201605.500000 1808592.500000 2229048.000000 1 Projected GCS_North_American_1983 NAD_1983_StatePlane_California_IV_FIPS_0404_Feet <ProjectedCoordinateSystem xsi:type='typens:ProjectedCoordinateSystem' xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xmlns:xs='http://www.w3.org/2001/XMLSchema' xmlns:typens='http://www.esri.com/schemas/ArcGIS/10.3'><WKT>PROJCS["NAD_1983_StatePlane_California_IV_FIPS_0404_Feet",GEOGCS["GCS_North_American_1983",DATUM["D_North_American_1983",SPHEROID["GRS_1980",6378137.0,298.257222101]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Lambert_Conformal_Conic"],PARAMETER["False_Easting",6561666.666666666],PARAMETER["False_Northing",1640416.666666667],PARAMETER["Central_Meridian",-119.0],PARAMETER["Standard_Parallel_1",36.0],PARAMETER["Standard_Parallel_2",37.25],PARAMETER["Latitude_Of_Origin",35.33333333333334],UNIT["Foot_US",0.3048006096012192],AUTHORITY["EPSG",2228]]</WKT><XOrigin>-116466200</XOrigin><YOrigin>-92735300</YOrigin><XYScale>4000</XYScale><ZOrigin>0</ZOrigin><ZScale>1</ZScale><MOrigin>0</MOrigin><MScale>1</MScale><XYTolerance>0.002</XYTolerance><ZTolerance>0.002</ZTolerance><MTolerance>1.9999999999999998e-005</MTolerance><HighPrecision>true</HighPrecision><WKID>102644</WKID><LatestWKID>2228</LatestWKID></ProjectedCoordinateSystem> Linear Unit: Foot_US (0.304801) 1.0 Version 6.2 (Build 9200) ; Esri ArcGIS 10.3.0.4322 Liquefaction -121.991705 -120.213947 36.943886 35.758422 1 -121.991705 -120.213947 36.943886 35.758422 1 002 ISO 19115 Geographic Information - Metadata DIS_ESRI1.0 dataset 002 withheld Feature Class Feature Class NAD_1983_StatePlane_California_IV_FIPS_0404_Feet EPSG 8.2.6 621 20180410