Basic Seismology

• Worldwide distribution of earthquake epicenters -- map
• Generation of earthquakes at plate boundaries -- diagram
• Focal depth and plate boundary types -- diagram showing focal depth of earthquakes at different types of plate boundaries
• Elastic rebound -- diagram showing principle of strain buildup, rupture, and elastic rebound
• Focus and epicenter -- definition sketch of earthquake focus and epicenter
• P-wave propagation -- diagram showing how a P-wave (compressional wave) moves
• S-wave propagation -- diagram showing how an S-wave (shear wave) moves
• P, S and L waves -- diagram comparing propagation of P, S and L (surface) waves
• Seismogram and travel-time curves
• Epicenter location -- diagram showing how an epicenter is located
• Principles of seismic refraction -- diagaram showing bending of earthquake waves as they move into materials with different seismic wave velocity. Velocity increases with increasing stiffness, decreases with increasing density.
• P and S -wave shadow zones -- diagram showing the P and S -wave shadow zones caused by the earth's core. These shadow zones are our evidence for the existence of the core, determination of its size, and knowledge that the outer core is liquid.
• Seismic wave velocities and earth's internal structure -- diagram showing how velocity of S and P waves varies with depth in the earth 

Strike-Slip Faults -- Physical evidence for inferring fault location and activity

• Offset sidewalk -- evidence for creep along San Andreas Fault in Hollister, CA
• Offset wall -- evidence for creep along San Andreas Fault in Hollister, CA
• Offset gullies -- evidence for movement along San Andreas Fault, Carrizo Plains
• Offset ridges -- evidence for movement along San Jacinto Fault near Hemet, CA
• Sag ponds and pinch-up ridges -- these mark the trace of the San Andreas Fault as it crosses the Carrizo Plains
• Sag pond -- small pond formed along trace of San Andreas fault -- suggests fault is active because such ponds typically are filled within a few thousand years if not rejuvenated by continued fault movement
• Line of sag ponds -- this line of ponds north of San Jose marks the trace of the San Andreas Fault
• Fault gouge -- brecciated (sheared and broken ) granite along the trace of the San Andreas. This material is weak and easily eroded.
• Linear fault valley -- the valley of the Garcia River in Mendocino Co. follows the weaker sheared rocks along the trace of the San Andreas Fault.
• Fault zones near San Francisco -- map showing the major branches of the San Andreas Fault south and east of San Francisco
• Linear fault valley -- the trace of the San Andreas on the San Francisco Peninsula is marked by a prominent linear valley eroded in the weaker sheared rocks along the fault.
• Linear fault valley -- aerial view NW along the San Andreas fault on the San Francisco Peninsula
• Linear fault valley -- another aerial view NW along the San Andreas on the San Francisco Peninsula
• A geological nightmare, or how to do everything wrong -- trace of San Andreas near Mussel Rocks south of San Francisco. Development is built directly across fault zone, partially on fill, partially on weak unconsolidated rocks near steep, landslide-prone cliff.
• Hayward Fault -- air photo showing trace of Hayward Fault through Berkeley
• Offset fence -- fence near Olema offset 2.5 m by 1906 earthquake on San Andreas
• Groundwater effects -- in this area near Palmdale, the San Andreas acts as a barrier to groundwater flow, causing a difference in vegetation density across the fault. The fault can easily be mapped on this basis. 

Damage From Earthquakes

• Geologic control of earthquake intensity -- two identical adjacent buildings in Turkey: one built on old river deposits collapsed, while the other on bedrock appears undamaged.
• Failure of brick building -- Arvin-Tehachapi earthquake, 1952
• Failure of "earthquake-resistant" building -- Olive View Hospital failed in the 1971 San Fernando Valley earthquake because it was designed to withstand 0.5 g acceleration (the design standard of the time) and it experienced about 1 g accelerations.
• Earthquake resistance of wood frame building -- buidng actually cut by fault trace of 1971 San Fernando Valley earthquake diod not collapse.
• Caracas earthquake 1967 -- pancake collapse of upper floors of concrete apartment building
• Caracas earthquake 1967 -- pancake collapse of concrete high-rise apartment building
• Caracas earthquake 1967 -- close up of pancake collapse of concrete high-rise apartment building
• Mexico City earthquake 1985 -- partial pancake collapse of concrete parking structure 
• Mexico City earthquake 1985 -- partial failure of highrise buiding
• Armenia earthquake 1988 -- collapse of poorly-constructed concrete building
• Filled ground in northern San Francisco -- aerial view showing areas of natural and artificial fill
• Artificial fill in San Francisco -- Hunters Point - Candlestick Park vicinity
• Subsidence and damage on fill in the Marina District -- following the 1989 Loma Prieta earthquake
• Freeway collapse on fill in Oakland -- following the 1989 Loma Prieta earthquake
• Geologic map of Anchorage -- showing areas underlain by Bootlegger Cove Clay
• Geologic cross-section of Anchorage -- showing areas underlain by Bootlegger Cove Clay
• Ground subsidence in downtown Anchorage -- due to liquefaction of Bootlegger Cove Clay in 1964 earthquake
• Turnagain Heights landslide aerial overview -- large landslide in Anchorage caused by liquefaction of Bootlegger Cove Clay during 1964 earthquake
• Turnagain Heights landslide -- close-up of damage caused by the slide
• Turnagain Heights -- perspective sketch showing area before and after 1964 earthquake-induced landslide
• Turnagain Heights slide development -- cross-sections showing development of the slide during 1964 earthquake
• Sand boils near Watsonville, CA -- formed when liquefied saturated sand squirted to the surface in 1989 Loma Prieta earthquake
• Tsunami damage at Valdez, Alaska -- following 1964 Anchorage earthquake
• Tsunami damage, Alaska -- trees snapped off by tsunami following 1964 Anchorage earthquake
• Tsunami design -- RNP headquarters in Crescent City designed to be above possible tsunami level
• Seismic risk map of North America -- map showing areas of greatest and least seismic risk 

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