Geology 001                                                                                        West Valley College

Physical Geology                                                                                   Fall 2000


Study Questions 17: San Andreas Fault System


1)      What is the San Andreas Fault System?  On a map, be able to identify four San Francisco Bay Area faults that make up the San Andreas fault system in the Bay area.



2)      What type of fault is the San Andreas?



3)      What is creep and how does if differ from a long-term slip rate?



4)      What are the two reasons why understanding the long-term slip rate is important?



5)      Name two Bay Area faults that creep.  What part of the San Andreas fault proper is a creeping segment. (page 381)



6)      What is the average rate of movement on the San Andreas Fault over the past 1800 years? (page 360)



7)      What is the rate of plate motion between the Pacific and North American plates in the past 3 to 4 million years? (page 361)



8)      What makes up the difference between the two rated calculated in the two problems above?



9)      What is a seismic gap, and what is the seismic gap theory?



10)  What is the most dangerous fault in the San Francisco Bay Area?



11)  Why is the fault referred to in question above considered to be the most dangerous?



12)  Where is Parkfield and why has there been so much interest among geologists concerning Parkfield? What is the average time between magnitude 6.0 quakes on this segment of the fault before the most recent quake? When did the last quake occur at Parkfield and what was the magnitude?




13)  What are three sources of seismic waves?



14)  What is a restraining bend in a strike slip fault (sketch it)?



15)  Where is the Big Bend in the San Andreas fault, and how does it cause compression? (p. 384)



16)  What geologic province is the result of the Big Bend compression?


17)  What is the significance of Pallet Creek? (page 386)


18)  On what type of faults have three recent Big Bend area earthquakes (San Fernando quake of 1971, Whittier Narrows quake of 1987, Northridge quake of 1994) occurred on? (see page 391)



19)  How old is the San Andreas? (see page 364)


20)  What geologic features, units do geologists use as criteria for 315 km of movement on the San Andreas in the past 23.5 million years? (p. 361-363)


21)  Approximately how many km of rupture patch occurred during the Loma Prieta earthquake?


22)  What type of movement occurred on the San Andreas Fault?


23)  Where is the Carrizo Plain? What are sag ponds, offset streams, compressional ridges, and linear valleys. (p. 365 and p. 382)


24)  How much slip occurred in the Carrizon Plain as a result of the 1857 Fort Tejon earthquake? (page 384)