July Chapter Field Excursion

July 10, 2010

Field Excursion: Mitigating Fault Rupture Hazards on the Hayward Fault in Berkeley and Fremont, California: Integrating Geologic Information and Engineering Design

Time: 9:30 am – 3:00 pm

Venue: UC Berkeley & Fremont Central Park & BART Fremont Station

Map of Field Excursion Route

This field excursion offers visits to two sites along the active Hayward fault that highlight recent engineering mitigations for fault rupture hazards. Recent scientific consensus suggests that the Hayward fault has a relatively high probability of producing a large earthquake that will break the ground surface and possibly impact structures overlying the fault trace.

On the southern part of the Hayward fault in Fremont, the Warm Springs Extension (WSX) of the Bay Area Rapid Transit (BART) rail system is under construction at the fault crossing directly south of the Fremont BART station. Numerous paleoseismic trenches have been completed along Walnut Avenue and at the Tule Pond (Tyson’s Lagoon) site, and help define the location and likely characteristics of surface fault rupture at the WSX BART crossing, which involves an aerial structure over Walnut Avenue that merges with a 9-m-high earthen embankment across Tule Pond. The initiation of construction at the Tule Pond fault crossing provides an exciting update to the fault evaluation, and construction monitoring has helped ensure that mitigation designs are consistent with geologic conditions. The fault characteristics, expected displacements, and engineering mitigation design will be discussed during the field visit.

On the northern part of the Hayward fault on the University of California, Berkeley campus, a seismic retrofit of the Bowles Hall residential building was completed earlier this year. The retrofit design included features to accommodate surface rupture along the fault, which underlies the southeastern corner of the 82-year-old historic building.  Geologic mapping and trenching define the fault characteristics near the building, and help define the expected type and amount of earthquake-related deformation. Engineering design involves a mat foundation, a moat adjacent to the structure, and a retaining wall system, which help the building resist fault offset and survive the earthquake.

The trip will include brief discussions of the geologic characteristics and engineering designs for both sites. The visits may involve short walks in the site vicinity; sturdy shoes recommended.  Travel to and from both sites not provided; carpooling is encouraged.  Both sites are within walking distance from existing BART stations.  Family and friends are invited to participate and enjoy the trip.

Please RSVP by July 6 to chapterinfo@eerinc.org

Schedule for Saturday July 10, 2010:

9:30 am          Bowles Hall, University of California Berkeley campus (meet on NW side, parking lot)
11:00 am          Depart Berkeley for Fremont

12:00 pm          Lunch at Fremont Central Park (Bring your own…)
1:30 pm          Meet again BART Fremont Station, southeastern parking lot
3:00 pm        End

Map of Field Excursion Route

Image of Hayward Fault running through Fremont Central Park & Fremont BART:

Hayward Fault Fremont

EERI Northern California Chapter | c/o EERI National | 499 14th Street Suite 320 | Oakland, CA 94612-1934 USA | chapterinfo@eerinc.org