{ "culture": "en-US", "name": "MS48_MMI_PGA_2pc50", "guid": "", "catalogPath": "", "snippet": "This image service is part of a collection of 8 MMI maps that allow users to visualize and compare seismic hazards in terms of MMIs in various areas of California. They illustrate that the highest hazard areas are near major active faults. However, damaging earthquake shaking is possible anywhere in California. Factors such as proximity to faults and local geologic conditions influence shaking intensity. Comparing maps of MMIs derived using different GMICEs demonstrates large uncertainty in MMI calculations.", "description": "
The California Geological Survey (CGS) Map Sheet 48 (MS48) provides a depiction of expected ground shaking intensity from future earthquakes across the state. The shaking intensity is represented using the Modified Mercalli Intensity (MMI) scale, which describes the perceived earthquake shaking and correlates strongly with earthquake-induced damage. MS48 maps the level of shaking with a 2% probability of being exceeded in 50 years, equivalent to a 2,475-year average recurrence interval.<\/div>

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In addition to MS48, eight interactive MMI hazard maps are presented. These include MMIs calculated using alternative methods. For each method, MMIs at two different hazard levels were presented: one with a 2% probability of being exceeded in 50 years (equivalent to 2,475-year recurrence interval) and the other with 10% probability of being exceeded in 50 years (equivalent to 475-year recurrence interval). The Arc GIS interface allows users to select any two MMI hazard maps to compare side by side. \nMMI values were calculated using several ground motion to intensity conversion equations (GMICEs). See the \u201cScientific Background\u201d on MS48 webpage for detailed information.<\/div>

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Due to software limitations, symbology cannot be added to this service. To match the symbology used in the <\/i>MS48 MMI application<\/i><\/a>, use the following configuration:<\/i><\/font><\/div>
  • Number of Classes: 7<\/i><\/font><\/li>
  • Classes & Hex Codes:<\/i><\/font><\/li>
  • 4 - 5: #ffffbf<\/i><\/font><\/li>
  • 5 - 6: #f5f500<\/i><\/font><\/li>
  • 6 - 7: #f7ce00<\/i><\/font><\/li>
  • 7 - 8: #fa7d00<\/i><\/font><\/li>
  • 8 - 9: #fd2a00<\/i><\/font><\/li>
  • 9 - 10: #c70808<\/i><\/font><\/li>
  • 10 - 11: #8c0808<\/i><\/font><\/li><\/ul><\/div><\/div>", "summary": "This image service is part of a collection of 8 MMI maps that allow users to visualize and compare seismic hazards in terms of MMIs in various areas of California. They illustrate that the highest hazard areas are near major active faults. However, damaging earthquake shaking is possible anywhere in California. Factors such as proximity to faults and local geologic conditions influence shaking intensity. Comparing maps of MMIs derived using different GMICEs demonstrates large uncertainty in MMI calculations.", "title": "Map Sheet 48 (2025 update) - MMI from PGA (2% in 50 years)", "tags": [ "MS48", "Map Sheet 48", "California Geological Survey", "CGS", "Earthquake Shaking Potential", "California Department of Conservation", "California Natural Resources Agency", "CAOpenData" ], "type": "Image Service", "typeKeywords": [ "ArcGIS Server", "Data", "Image Service", "Service" ], "thumbnail": "", "url": "https://gis.conservation.ca.gov/server", "minScale": 1.8489297737236E7, "maxScale": 288895.277144, "spatialReference": "WGS_1984_Web_Mercator_Auxiliary_Sphere", "accessInformation": "Rui Chen, 2025, Map Sheet 48: Earthquake Shaking Potential for California, California Geological Survey, California Department of Conservation, California Natural Resources Agency, CAOpenData", "licenseInfo": "
    Access Constraints: Because digital data are easily altered, cities, counties, and others who use this are advised to obtain the file directly from the Department of Conservation, California Geological Survey.<\/div>

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     LICENSE AGREEMENT: (c) 2025 California Department of Conservation, California Geological Survey. All rights reserved. No part of these data may be reproduced, transmitted, or distributed in any form or by any means, electronic or mechanical for any purpose, without the express written permission of the California Geological Survey. <\/div>

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    Distribution Liability: These data are provided by the California Department of Conservation, California Geological Survey, as is. Any express or implied warranties, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose are disclaimed. In no event shall the California Department of Conservation, California Geological Survey, or its associated contributors be liable for any direct, indirect, incidental, special, exemplary, or consequential damages (including, but not limited to, procurement of substitute goods or services; loss of use, data, or profits; or business interruption) however caused and on any theory of liability, whether in contract, strict liability, or tort (including negligence or otherwise) that arise in any way out of the use of these data and software, even if advised of the possibility of such damage.<\/div>

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    The California Department of Conservation, California Geological Survey, makes no warranty, express or implied, regarding the data or its use. It is recommended that careful attention be paid to the contents of any metadata associated with a specific file, and that the originator of the data be contacted with any questions regarding appropriate use. The California Department of Conservation, California Geological Survey, shall not be held liable for improper or incorrect use of the data described and/or contained herein.<\/div>" }