Alquist-Priolo Earthquake Fault Zoning Program An Update Tim McCrink California Geological Survey COSMOS 11/14/2014 Photo by W. Bryant TOPICS COVERED Brief Background New Funding New Tools New Map Format New Areas Recent Events Alquist‐Priolo Earthquake Fault Zoning The 1971 Mw 6.6 San Fernando earthquake was associated with surface fault rupture that damaged or destroyed many structures. Severe damage – buildings unsafe – 30% vs. 5% Moderate or worse damage – 80% vs. 30% Fault Rupture Damage 1971 San Fernando Earthquake ALQUIST‐PRIOLO FAULT EVALUATION AND ZONING Earthquake Fault Zones are regulatory zones, delineated by the State Geologist (California Geological Survey), that encompass hazardous faults, which are defined as those faults that are sufficiently active and well‐defined. Sufficiently active Fault that exhibits evidence of Holocene displacement (approx. last 11,000 years). Well‐defined Trace detectable by trained geologist at or just below ground surface. MITIGATION WITHIN EARTHQUAKE FAULT ZONES AP Act only allows surface fault rupture mitigation by avoidance Section 2621.5 of Public Resources Code and Section 3600 of California Code of Regulations: “…prohibit the location of developments and structures for human occupancy across the trace of active faults.” Sect. 3603.(a) of California Code of Regulations: “No structure for human occupancy…shall be permitted to be placed across the trace of an active fault.” SETBACK FROM ACTIVE FAULTS California Code of Regulations [§ 3603.(a)] states: “…as the area within 50 feet of such active faults shall be presumed to be underlain by active branches of that fault unless proven otherwise by an appropriate geologic investigation and report prepared as specified CCR § 3603.(d) of this subchapter, no such structures shall be permitted in this area.” As written, there is no minimum distance. What is considered a Project under the Act The Act is applicable to any project, as defined in CPR § 2621.6, which is located within a delineated Earthquake Fault Zone (EFZ) [CPR § 2621.5(b)] Any subdivision of land subject to the Subdivision Map Act, and which contemplates the eventual construction of structures for human occupancy [CPR § 2621.6(a)(1)] Structures for human occupancy, with these exceptions [CPR § 2621.6.(a)(2)]: (A) Single family dwellings (wood-frame or steelframe) to be built on parcels of land for which geologic reports have been approved pursuant to paragraph (1) (B) Single family dwellings (wood-frame or steelframe) not exceeding two stories, when not a part of a development of 4 or more dwellings EARTHQUAKE FAULT ZONE MAPS (1974 – 2014) Sacramento San Francisco Los Angeles September 12, 2012 6 7 ‐ November 6, 2014 1 1 ‐ Totals 169 4 558 36 Counties and 105 Cities Affected NEW FUNDING • July 1, 2014 • Funding Source SMISHM • 30% Increase for AP NEW TOOLS LiDAR LiDAR – A Great Tool for Geomorphic Interpretation 8/2005 Google Earth 2010 LiDAR Gordon Seitz West Tahoe Fault LiDAR – A Great Tool for Geomorphic Interpretation With Limitations 1930 Spence Air Photo 2005 B4 LiDAR ‐ 315° San Andreas Fault ‐ Indio NEW TOOLS InSAR/UAVSAR – NASA JPL – Interferograms – e‐Decider Deformation Modeling – ARIA Damage Proxy NEW TOOLS Multi‐ and Hyper‐Spectral Imagery Image Fusion Perez, F.G. Bryant, W.A. Treiman, J.A. Real, C.R. NEW TOOLS Digital Photogrammetry Vintage Aerial Photography 1924 1978 NEW MAPS All Zones, One Map PDF - Hollywood Quadrangle EFZ Map GEO-PDF - Hollywood Quadrangle GEO-PDF - Hollywood Quadrangle NEW AREAS West Tahoe Fault West Napa Fault Sacramento San Francisco Hollywood/Santa Monica Faults Hollywood/Raymond Faults Helendale Fault Los Angeles Southern SAF Whittier Fault Southern SAF RECENT EVENTS South Napa Earthquake GEER Report – Browns Valley West Napa Fault – Triggered Slip RECENT EVENTS Hollywood and Azusa Zone Maps Los Angeles Seismic Safety Element Millennium Hollywood GEO-PDF - Hollywood Quadrangle QUESTIONS?