TranSystems Corporation - LGM Construction

6.0 GEOLOGIC HAZARDS
Geologic hazards reviewed for this project include seismic ground shaking, fault ground
rupture, liquefaction, cyclic densification, and lateral spreading.
6.1 SEISMIC GROUND SHAKING
It is important to note that the site is in a region of high seismic activity. Historically, the
site has been subjected to intense seismic activity. We expect the site to be subjected
to substantial ground shaking due to a major seismic event on the surrounding faults,
especially the active Hayward Fault during the life of the project (assumed at 50 years).
Some degree of structural damage due to strong seismic shaking should be expected.
Periodic slight to moderate earthquakes should also be expected.
6.2 FAULT GROUND RUPTURE
Based on our review of the referenced geologic maps, the project area is not underlain
by known active faults (i.e., faults that exhibit evidence of ground displacement in the
last 11,000 years), nor does the site lie within an Alquist-Priolo Earthquake Fault Zone.
Therefore, the potential for ground rupture due to faulting through the building is
considered low. However, the site does fall within 7.2 km of the Active Hayward Fault,
and thus all structures should be designed, at a minimum, per the 2007 California
Building Code (CBC).
6.3 LIQUEFACTION
Soil liquefaction is a condition in which saturated, granular and low-plasticity cohesive
soils undergo a substantial loss of strength and deformation due to pore pressure
increase resulting from cyclic stress application induced by earthquakes. In the
process, the soil acquires mobility sufficient to permit both horizontal and vertical
movements if the soil mass is not confined. Structures founded on or above potentially
liquefiable soils may experience bearing capacity failures due to the temporary loss of
foundation support, vertical settlements, and undergo lateral spreading. Soils most
susceptible to liquefaction are saturated, loose, clean, uniformly graded, and finegrained
sand deposits. However, based on recent observations and study, under
94240/1(OAK8R061)/es Page 12 of 29 June 13, 2008
© 2008 Kleinfelder