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1906 Earthquake Centennial Alliance

Activities & Events

Tracing the Hayward Fault - A Potential Disaster Area

N. California Geological Society

The Hayward fault is a major branch of the San Andreas Fault system in northern California. Many geomorphic features that are indicative of active movement on the Hayward fault have been destroyed by urbanization.

This field trip will center on two segments of the Hayward Fault where surface features can still be observed. The first part will center on the Fremont area near Tule Ponds and the second part will look at the Hayward area.

Tule Ponds at Tyson Lagoon has been a site of fresh water for at least the last 3700 years. This sag pond outlines the trace of the Hayward fault zone in this area. Observations of brittle deformation and liquefaction features in trenches just north of this area indicate there may have been 6-8 large earthquakes during the last 2000 years (Lienkaemper et al., 2002). Participants will be able to see a peel of one of the trenches to observe stratigraphic features.

After walking along the two traces of the Hayward Fault, we will walk south of Tule Ponds to observe evidence of movement along Walnut Ave. The walk will continue toward Lake Elizabeth to observe other geomorphic and structural features.

We leave Fremont and drive north along Mission Blvd. to Hayward. For most of this stretch, the active trace of the fault runs parallel to Mission Blvd. and is seldom more than a quarter mile away from the road. Abundant geomorphic evidence of the fault can be seen from the road, including linear ridges that block stream drainages.

At Palisade Street, creep of the fault caused offset of sidewalk and curbing. At Spring Drive, the fault acts as a groundwater barrier and has created a natural spring. At Hayward Memorial Park, a stone wall built in the 1930s has been offset by fault creep.

In downtown Hayward we follow the active trace of the fault on foot and observe evidence of fault creep in offset sidewalk curbs, offset walls of buildings, and en-echelon cracks of asphalt pavement.

The wall of one brick building is being pulled apart at its base but is still connected at its top. The old Hayward City Hall sits astride the active trace and has been damaged by fault creep. San Lorenzo Creek, which crosses the Hayward fault in downtown Hayward, has evidently been offset approximately one mile by accumulated slip and creep along the fault.

More information »

When

Saturday April 15, 2006, departing at 8:30 am (sharp) for this daylong field trip.

Pre-registration required. View/print field trip information and registration form at: http://www.ncgeolsoc.org/Hayward%20Fault%20FT/Hayward%20Fault%20FT.pdf

Where

Departure point:
Math/Science Nucleus (MSN)
4074 Eggers Drive
Fremont, CA 94536

For directions to MSN, visit http://www.msnucleus.org/mapegg.html

Field trip will take us from Fremont to Hayward.

Relevance

To increase general awareness of the larger strike-slip fault system that is a part of the plate boundary in the Bay Area. This field trip will be lead by Dr. Joyce Blueford of the Math Science Nucleus, Fremont (formerly with the USGS) and Dr. Mitchell Craig, CSU, East Bay.

Audience

Professionals and general public.

Contact

Tridib Guha, (925) 370-0685

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