SAFETY ELEMENT SAN LUIS OBISPO COUNTY· GENERAL PLAN' TECHNICAL BACKGROUND REPORT SAN LUIS OBISPO COUNTY DEPARTMENT OF PLANNING AND BUILDING / December 1999 Board of Supervisors Harry Ovitt, District 1 Shirley Bianchi, District 2 Peg Pinard, District 3 Kacho i\chadjia", District 4 Ivlichael Ryan, District 5 Planning Commission Clifford J. Smith, Dimict 1 Doreen Liberto-Blanck, District 2 Pat Veesarr, District 3 Diane Hull, District 4 Wayne Cooper, DistrictS Department of Planning and Building Victor Holanda,AICP, Director Bryce Tingle, AlCP, Assistant Director., Warren Hoag, AICP, Principal Planner, ]\foj~ct M~nager John Nail, Principal En';;;:~);;ii~c;:;taISpecialist' ' ' John Kelly, Supervising Mapping/Graphics Technician Dan Lambert, Mapping/Graphics Technician , Technical Advisory Commiliee County of San Luis Obispo: Ron Alsop, County Office of Emergency Services Susan Litteral, Engineering""'''m'''' Tony Boyd, Engineering , ; ..... Ben Stewart, CDF/County Fire Ben Parker, CDF/County Fire Robert Lewin, CDF/County Fire City Representatives: Helen Elder, Arroyo Grande Steve DeCamp/Gary Kaiser, Atascadero Thomas Sullivan/Sandra Bierdzinski, Grover Beach Shawla Nauman) rvforro Bay Mary Oien, Paso Robles Glen Matteson, San Luis Obispo Consultant Team Fugro West, Inc. Crawford Multari Clark & Mohr Don Asquith, PhD, CEG eJ Poly, Landscape Architecture Department (GIS) TccJmicai Background Report County and Cities of San Luis Obispo List of Tables 1. Emergency Response & Planning None. 2. Water Hazards Table 2-1: Major Dams and Reservoirs in San Luis Obispo County .............................................................. 17 3. Fire Hazards Table 3-1: Likely Fire Hazard Severity Rated by Fuel Conditions Only ....................................................... 28 Table 3-2: Major Wildfires in San Luis Obispo County Since 1931 ............................................................... 30 Table 3-3: Urban/Wildland Interface Areas of San Luis Obispo COunty ................................................. ,... 33 Table 3-4: Fire Stations in the Unincorporated Areas of San Luis Obispo County ............. ,...................... 38 4. Geology & Seismic:ity Table 4-1: Geologic Time Scale ............................................................................................................................ 47 Table 4-2: Seismotectonic Domains in San Luis Obispo.c:cmnty .......................... ;........ :...... ,..................... :.. 5L Table 4-3: Modified Mercalli Intensity Scale ...... :.................................................. :.. :.......................................... 54· Table 4-4: Faults Listed in Current CDMG Database ...................................................................................... 55 Table 4-5: Other Faults in and near San Luis Obispo County ........................................................................ 56 Table 4-6: Thrust Faults Interpreted by Namson & Davis (1990) ................................................................. 57 Table 4-7: Selected Historical Earthquakes with M~.O in Coastal Central California from 1830 through 1989 ............................................................................................................ ;........ 67 Table 4-8: Fault Rupture Hazard ................................................................................................................ :......... 70 Table 4-9: Sources of Ground Shaking in the Vicinity of Arroyo Grande ................................................... 80 Table 4-10: Sources of Ground Shaking in theVlciD.ity of Atascadero ............ :............................................. 81 Table 4-11: Sources of Grou~d Shaking in the Vicillity'o(Crover Beach .......... :.. :........ :............... :.: ............ 82 Table 4-12: Sources of Ground Shaking in the Vicinity of Morro Bay ............................................ ;.; ............ 82 Table 4-13: Sources of Ground Shaking in the Vicinity of Paso Robles ........................................................ 83 Table 4-14: Sources of Ground Shaking in the Vicinity of San Luis Obispo ................................................ 84 Table 4-15: Vulnerability to Liquefaction .............................................................................................................. 85 Table 4-16: Historical Tsunamis ............................................................................................................................. 88 Table 4-17: Landslide Hazard and Slope Instability Potential ........................................................................... 92 5. Other Hazards Table 5-1: Diablo Canyon Power Plant Protective Action Zones (PAZ) and Public Education Zones (PEZ) ...................................................................................................... 107 Table 5-2: Examples of Magnetic Fields at Distances from Appliance Surfaces ..................................... 111 6. Referenc:es None. Tech{1icaJ Background Report County and Cities of San Luis Obispo Contents 1. Emergency Response & Planning •...••.••••••••••.•.•••.••••.••.•••...•..•••.•.•.•......•..•..•••.•••••• 1 San Luis Obispo Gmnty Office of Emergency Services ...................................................... :: ......................... 1 Disaster Response and Planning ..................................................................... ,.......................... ;: ......................... 2 Incident Command System .............................. , .......................................................................... : .......................... 2 Multi-Agency Coordination ................................................................................................................................... 3 Mutual Aid Agreements ......................................................................................................................................... 3 Operational Areas ................................................................................................................................................... 3 Operational Area Satellite Information System (OASIS) ................................................................................ 3 Emergency Response Corridors and Evacuation Routes ................................................................................. 3 2. Water Hazards ..........••...•..........•.•••.........•••...................•.•...............•............•••... 5 . Flooding ...................................................................... :............................................................................................. 5 Dam Inundation ..................................................................................................................................................... 17 Coastal Erosion ...................................................................................................................................................... 22 3. Fire Hazards .....••••...........................•.•.........•.•••.•..................•..••••....~ ..••.•......•••• 27 Wildfires .................................................................................................................................................................. 27 Urban Fire Hazards ........................................................................................................................................ ,...... 35 -.e '." • " - 4. Geology & Seismicity .....................•.•• ~ ............................... ;.:.'i. •••••.••• ~ •• ~ •••••' •••••••••••••• 47 Geologic Tune Scale ................................................................................ ;........... ,................................................ 47 Regional Geology .................................................................................................................................................. 48 Stratigraphy ............................................................................................................................................................. 50 Seismicity ................................................................................................................................................................ 51 Fault Activity ................................................................................................................. ,....................................... 51 Measurement of Earthquakes ............................................................................. :..................... ~ ......................... 53 Faults in San Luis Obispo County .......................................................................................... i.......................... 53 Fault Rupture ..................................................................... ,.................................................................................... 69 Unincorporated San Luis Obispo County ........................................................................................................ .71 Groundshaking ................................................................................................................................. :: .................... 75 Liquefaction ................................................................................................................. ;...... ;................................... 84 Tsunami and Seiches .............................................................................................................................................