2 Strike-Slip Faulting, Flower Structures, Plutons, and Tiltmeters I: A Tribute to the Career of Arthur Sylvester

Wednesday, 17 May 2023
8:00 AM - 12:00 PM
Whitney Peak Ballroom 1

PUBLIC POLICY: USE AND POTENTIAL MISUSE OF THE A-P ACT IN CALIFORNIA

Paper number: 2-13
Program: Theme Sessions
Time: 11:40 AM – 12:00 PM

Authors

  • Roy Shlemon Presenting Author
    University of California, Davis, Newport Beach, CA
  • Stephen Testa
    Testa Environmental Corporation, Mokelumne Hill, CA

Abstract

The Alquist-Priolo (A-P) Act was enacted in 1972 following the 1971 Sylmar earthquake in southern California. Its main intent is to preclude construction of habitable structures across active faults, now defined as surface or near-surface displacement within the last 11,700 years. Administration and implementation of the Act is conducted by the California Geological Survey (CGS) for defining, delineating and establishing “Earthquake Fault Zones” (EFZ’s); by the State Mining and Geology Board for regulation; and by lead agencies (usually counties or cities) for technical reviews. These procedures have worked reasonably well over the past 50 years. Now, however, as new “active fault zones” are imposed on densely urbanized areas, some developers and, unfortunately, their geological consultants, are increasingly seeking to avoid A-P restrictions by taking advantage of so-called “remodeling exemptions.” These exemptions are intended to reduce the economic burden of urban fault investigations for owners of “small properties” situated on known or likely active faults. The exemptions largely apply to existing structures of four or fewer units, but details vary from jurisdiction to jurisdiction. In general, A-P fault-investigations are not required when remodeling up to 50 percent of an existing structure’s value, excluding that of the underlying land. Given the high cost of urban properties, a few unscrupulous developers, and their supporting consulting geologists, now complete exemption remodeling, then apply for another 50 percent remodel, often within a year or two. This, effectively, defeats the intent of the A-P Act. Unfortunately, too, despite adhering to policies of “public health and safety,” this “A-P Zone remodel avoidance” is often unwittingly abetted by local jurisdictions eager for land redevelopment and the resulting increased tax base.

Geological Society of America Abstracts with Programs. Vol. 55, No. 4

doi: 10.1130/abs/2023CD-386449

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