www.consrv.ca.gov/dmg/

Ten New Seismic Hazard Zone Maps Released

FEBRUARY 2001 BULLETIN #10

Cities affected by these ten new maps.

SOUTHERN CALIFORNIA

T en new Seismic Hazard Zone mapscovering parts of Orange, Ventura,Los Angeles, Santa Clara counties and

the City and County of San Francisco havebeen released. The November 17, 2000 re-lease covers the Moorpark, Mt. Baldy, Ontar-io, Thousand Oaks 7.5-minute quadranglesand the City and County of San Francisco.These new maps affect the cities of AgouraHills, Claremont, La Verne, Pomona, Moor-park, San Francisco, Simi Valley, ThousandOaks and Westlake Village.

The liquefaction zones for the northernportion of San Francisco were released onApril 7, 1997. The new release supercedesthe 1997 map and covers the entire city andcounty for both liquefaction and earthquake-induced landslides. The November 17 releas-es are indicated in green with heavy outlineon the index maps.

NORTHERN CALIFORNIA

continued next page . . . .

Anaheim Black Star Canyon,Prado Dam

Costa Mesa TustinIrvine El Toro, TustinLaguna Hills El ToroLake Forest El ToroMission Viejo El ToroNewport Beach TustinOrange Black Star Canyon,

Prado DamSanta Ana TustinTustin TustinYorba Linda Black Star Canyon,

Prado Dam

City Name Map NameORANGE COUNTY

City Name Map Name

LOS ANGELES COUNTY

Agoura Hills Thousand OaksClaremont Mt. Baldy, OntarioLa Verne Mt. Baldy, OntarioPomona OntarioWestlake Village Thousand Oaks

City Name Map NameVENTURA COUNTY

Moorpark MoorparkSimi Valley Thousand OaksThousand Oaks Thousand Oaks

City Name Map Name

SANTA CLARACOUNTY

San Jose San Jose East

City Name Map

SAN FRANCISCOCITY AND COUNTY

San Francisco San Francisco

The Division of Mines and Geology provided aninformation booth and presented 19 papers at

the Sixth International Conference on Seis-mic Zonation (6ICSZ). Thirty-one staff membersattended the November 12-15, 2000 conference.

This conference, the sixth in a series that beganin 1972, was attended by 350 people from 31 coun-tries. Last held in Nice, France in 1995, it drawsparticipants from around the world to an interna-tional forum where new seismic zonation technolo-gies are discussed and evaluated. Researchers andpolicy makers meet to share the latest advances inhazard identification, mapping, mitigation, andpublic policy.

Charles Real, DMG’s Seismic Hazards MappingProgram Manager, took a very active role as a mem-ber of the 6ICSZ’s conference steering committee. He also or-ganized the New Mapping Technology session, was a panelistfor New Developments in Hazard Estimation, presented twopapers, two posters, and guided DMG’s support role andstaff abstracts.

T. Leslie Youd was the conference chairperson. BruceClark led a pre-conference field trip. Earthquake EngineeringResearch Institute was the main sponsor of the conference

Division Takes Lead Role in International Zonation Conference

EVENTS CALENDAR

March 26-31, 2001

4th International Conference on RecentAdvances in Geotechnical EarthquakeEngineering and Soil DynamicsSan Diegowww.umr.edu

April 18-20, 2001Seismological Society of America2001 Annual MeetingCommemorating the 95th Anniversaryof the 1906 San Francisco EarthquakeSan Franciscowww.seismosoc.org/meetingsmsanders@usgs.gov

June 6-9, 2001

Incorporated ResearchInstitutions for Seismology13th Annual MeetingJackson Hole, Wyomingwww.iris.edu

and staff did an outstanding job accepting abstracts, registeringpeople and organizing the conference proceedings.The hard copy and CD-ROM version of the abstracts, andthe two-volume paperbound copy of the proceedings areavailable from EERI at:

Earthquake Engineering Research Institute499 14th Street, Suite 320Oakland, CA 94612-1934(510) 451-0905http://www.eeri.org

The most recent release, January 17, 2001, covers the Black StarCanyon, El Toro, Prado Dam, the revised Tustin, and the San JoseEast 7.5-minute quadrangles. These official maps affect the cities ofAnaheim, Costa Mesa, Irvine, Laguna Hills, Lake Forest, Tustin,Orange, Mission Viejo, Santa Ana, Newport Beach, Yorba Linda, andSan Jose.

The Tustin Quadrangle was originally released on April 15,1998. However, in preparing the El Toro Quadrangle to the east,historical high ground water level data necessitated a modificationof the seismic hazard zones. The January 17th quadrangle releasesare indicated in gold on the index maps. The maps are the productof a three-dimensional analysis of geotechnical and geologicaldata based on surface mapping and subsurface borings.

The Seismic Hazards Mapping Act (Public Resources Code –Chapter 7.8) requires the State Geologist to compile maps thatidentify Seismic Hazard zones within which site-specific geotech-nical assessments must be completed prior to permitting moststructures for human occupancy. The zones delineate areas whereliquefaction and earthquake-induced landslides are most likely tooccur. The goal of the Act is to improve public safety by incorpo-rating recommended improvements resulting from the detailedsite investigations into the development.

The release of these Seismic Hazard Zone Maps brings the totalofficial maps to 51, affecting six counties and 115 cities.

continued from first page . . .

Cindy Pridmore, Associate Engineering Geologist from DMG, withher poster of Liquefaction Hazard Evaluation in the South Gate7.5-Minute Quadrangle, Los Angeles, California: A Case Study.

The Division of Mines and Geology is mapping newways to make its information accessible to the public.

In September 2000, 3 years of digitizing our extensive in-ventory of Alquist-Priolo maps paid off with the release ofa CD-ROM containing the images of 235 maps for Imperi-al, Los Angeles, Orange, Riverside, San Bernardino, SanDiego, Santa Barbara and Ventura counties. The maps arewidely used by local governments as well as geologicalconsultants, real estate and construction industries. Twomore CDs — with Alquist-Priolo map images for the Cen-tral Coast Region and the Northern and Eastern Regions— will be released soon.

Digitized maps and reports have some major advantagesover the paper maps, including ease of storage and cost.

“Digitized maps are becoming the standard protocol,but we have more than 4,000 paper maps,” said TedSmith, Supervising Geologist of the Division’s TechnicalInformation and Support Program.

“If someone wanted to buy the 235 Alquist-Priolo mapsfor southern California on paper, they would cost $590. Inthis format, all of those maps are available for $30, andusers can print out whatever portion they need,” Smith ex-plained. “Plus, some of the companies and individuals thatwant these maps are reviewing hundreds of sites. With theCD, they can move from county to county and map to mapwith a click of the mouse.”

Paper Maps Get a New Image

“These Alquist-Priolo CDs are an interim product — imag-es only,” Smith said. “We’re on our way to producing CDsthat have both images and GIS files. Those should be avail-able in a few months. But right now we have a digital prod-uct that will help a lot of people who don’t need GIS data butdo need the maps.”

Afull day symposium was devoted to the Seismic Hazards Mapping Act and it’s impact on California

planning at the 43rd Annual Meeting of the Associ-ation of Engineering Geologists, held in San JoseSeptember 18-21, 2000.

Mark Wiegers (DMG’s San Francisco District Office)chaired the symposium. The morning session featuredeight speakers from the state and federal government de-scribing the newest geologic information, development ofshaking hazard maps and the current methodologies used inhazard analysis. The afternoon session featured speakersfrom local agencies, consulting firms and realty associationsthat discussed some of the regulatory issues facing cities andcounties when implementing the Act.

Special Publication 117 Guidelines for Evaluating andMitigating Seismic Hazards in California is the first of

three publications that present up-to-date information onseismic hazards evaluation.

This Special Publication can be purchased from:Department of ConservationDivision of Mines and Geology801 K Street, MS 14-33Sacramento, CA 95814-3532(916) 445-5716

or can be obtained from the Department web site at no cost:http://www.consrv.ca.gov/dmg/pubs/sp/117/index.htm

In March 1999, the Southern California Earthquake Cen-ter published Recommended Procedures for Implementation ofDMG Special Publication 117…Liquefaction in California:http://www.scec.org/outreach/products/publist4.html.

The American Society of Civil Engineers is currentlycirculating a draft version of Recommended Procedures forImplementation of DMG Special Publication 117…LandslideHazards in California: http://www.pubs.asce.org/.

Wiegers Chairs One-Day Symposiumat the 43rd AEG Annual Meeting

Seismic Hazard Guidelines

The Seismic Hazards MappingProgram Outreach Unit welcomes

Senior Engineering Geologist JackMcMillan as the Local Government Out-reach Coordinator. Jack has been map-ping landslide hazard zones since 1994.He has helped the outreach effort forthe past 3 years, distributing 43 officialzone maps and visiting jurisdictions todiscuss responsibilities and requirements under the law.

“Our plan is to expand this outreach unit to four peo-ple. Once fully staffed, it will allow us to provide increasedsupport to our map users and ensure that the seismic haz-ard maps are being used properly by local planners, build-ing officials and homeowners,” McMillan says.

Associate Planner Candace M. Hilljoined the Outreach Unit in May 2000.Candace came to the Department ofConservation from the SacramentoCounty Planning Department. She willbe responsible for implementation andcompliance issues with lead agencies andcoordinate our information and outreach

booths at professional conferences.

Ross Martin, Research Analyst, transferred from DMG’sTechnical Information and Support Pro-gram. Ross has an extensive graphics de-sign background that will enhance ournewsletters, map products and web pagematerial.

The fourth staff position depends onfunding. The Associate Engineering Geol-ogist position will be responsible for re-viewing the site investigations triggeredby the landslide and liquefaction zones and determine ifthe construction practices have led to safer construction.

In the past 6 months the outreach staff has providedinformation at the California Chapter of the American Plan-ning Association, Association of Engineering Geologists, andthe 6th International Seismic Zonation conferences.

We have also met with local agencies, delivering tenPreliminary Zone maps to the cities and counties affectedby the recently released maps prepared in northern andsouthern California.

In addition, we have participated in two public work-shops with the City and County of San Francisco, held pressconferences in Los Angeles and San Francisco, and coordi-nated with the City of San Jose on upcoming map releases.

The focus of this Unit over the next 2 years will be towork more closely with lead agencies to ensure that theseismic hazard maps are used in the development process.The resulting changes in construction can help reducestructural damage and loss of human life during futureearthquakes.

Outreach Unit Gears Up for Expanded Public Outreach Support

For information about the Seismic Hazards MappingProgram contact:

Jack R. McMillan, Senior Engineering GeologistOutreach Coordinator801 K Street, MS 12-31Sacramento, CA 95814Voice: (916) 323-8569Fax (916) 445-3334E-mail jmcmilla@consrv.ca.gov orCandace M. Hill, Associate Planner801 K Street, MS 12-31Sacramento, CA 95814Voice: (916) 322-2718E-mail chill@consrv.ca.gov

For information about the Alquist-Priolo EarthquakeFault Zoning Act contact:

Bill Bryant, Senior Geologist801 K Street, MS 12-31Sacramento, CA 95814Voice: (916) 323-9672Fax: (916) 322-4765E-mail: bbryant@consrv.ca.gov

CONTACT INFORMATION

This Bulletin is produced by the CaliforniaDepartment of Conservation’s Division of Minesand Geology to provide information about theSeismic Hazards Mapping Program and isprinted as new maps are released.The Department of Conservation posts informationto the web pertaining to the Seismic HazardsMapping Act and the Alquist-Priolo EarthquakeFault Zoning Programs at :http://www.consrv.ca.gov/dmg

REMINDER: FILING OF SITE INVESTIGATION REPORTS Cities, Counties, and State Agencies where official seismichazard zone maps have been released are required to send acopy of any required site investigation report to the State Geologistwithin 30 days of approval. The purpose of this submittal is to expedite future updates of thezone maps by DMG. The Department of Conservation has noreview authority, and does not approve or disapprove the reports.

Send reports to:

Department of ConservationDivision of Mines and GeologySeismic Hazards Mapping Program - Reports801 K Street, MS 12-31Sacramento, CA 95814