Clear evidence of fault creep is found in Fremont where Gardenia Way crosses the Hayward fault near Ivy. A sequence of fractures or shears forms diagonally across the asphalt pavement in the street.
The close-up of the fractures in the asphalt on Gardenia Way. These are an excellent example of left-stepping en echelon shears, where the next set of fractures is to the left of the last set. These result from right-lateral slip on the Hayward fault.
The Hayward fault can be identified in several locations crossing the streets in Fremont. Note the bend and break in the curbs at Rocket Drive.
SOUTH HAYWARD
On undeveloped hillslopes, the fault trace is marked by streams that are bent, almost at a right angle, by right-lateral movement of the fault. Right-lateral means that the land on the far side across the fault moves to the right. The stream channel was originally straight. But thousands of years of fault slip and creep have moved the stream eighty meters or about 260 feet to the right.
Continuing northward , this old fence at Holy Sepulchre Cemetery in south Hayward has been offset by fault creep more than 3 feet since it was built in the nineteenth century.
- In places, the Hayward fault can be observed at the surface as a line of green vegetation when the grass on the hills dries out in the springtime. The line of vegetation remains green because of seeps and springs formed along the fault.Springs form because the rock in the fault zone has been pulverized by fault movement and altered to clay. This pulverized rock and clay, called fault gouge, forms an underground dam. Water moving underground accumulates against the fault and comes to the surface as seeps, springs, or ponds.
A small gully on the hillslope above has been Holy Sepulchre Cemetery
has been offset by fault movement nearly 3 meters as illustrated by the
red stakes. This offset probably represents surface displacement in the
1868 Hayward earthquake and accumulated creep, plus possible offset in
an unknown earthquake before 1868.