Faults:  breaks in the earth's lithosphere, with movement along the break
     faults are planes, not lines, tilted or dipping at various angles into the ground
    fault trace is intersection of ground and fault (some faults don't break to surface)
     movement direction on fault can be anything; up, down, sideways, mixed.
     active faults have had movement within last 10,000 years: millions of faults in PNW
         ***plate boundaries are made of one or more giant faults separating plates
         ***most active faults are NEAR plate boundaries but are NOT plate boundaries
          ***only a few faults are plate boundaries; most faults are within plates, near edges

Earthquake:  ground shaking,  also known as seisms or temblors
      moving blocks along fault is NOT the same as ground shaking (earthquake)
     sources of earthquakes:  rapid fault movement (99%), magma, landslides, cave collapse
         ***fast movement of blocks along a fault PRODUCES/CAUSES ground shaking (quake)
     seismic faults (fast movement) versus aseismic faults (slow movement, no quakes)
     location:  focus/hypocenter (location of quake on fault), epicenter (spot above quake)
     size/magnitude of earthquake: 3 common scales/indices/measures of quake size
         Mercalli: based on amount of damage and human response (no instrument)
         Richter:  based on amount of ground shaking as measured by seismograph
         Moment: based on size of fault that moved and amount of movement on fault

Cascadia Subduction Zone = plate boundary between NAM and JDF, surfaces at trench
     a few quakes/year > Richter magnitude 2.  depths 20-80 km (only source of deep ones)
     last big quake:  26 Jan 1700 about 9 pm, most of CSZ "broke"/ruptured (whole fault....)
          know date and time precisely because of tsunami recorded in Japan.
      maximum: very large 8 to small 9, one of largest on Earth we know about
     1949 and 1965 quakes (both 6.7 ±) along CSZ, as well as 1999 Satsop 5.2

Mid-Crustal Fault/Detachment: within NAM plate, under Puget Sound, 20 km ±
     horizontal fault, never surfaces; over 10,000 km2 in area?
     a few quakes/month > Richter magnitude 2.  depths all around 20 km.
     large fault where upper cold brittle crust is "detached" from lower warm mooshy crust
     maximum size of quake unknown; if single fault, could be very large.

Shallow Crustal Faults:  within upper 20 km of NAM plate, widespread throughout WA
     a few quakes/week > Richter magnitude 2.  0-20 km depth, getting shallower to east.
     maximum size of quake depends on individual fault; Seattle Fault = big 7 to small 8
     faults include Seattle, South and North Whidbey Island, Duvall, Olympia, etc.
          some faults rupture surface, other faults do not
     Seattle Fault:  last big quake about AD 900, tsunamis, raised beaches, landslides, etc.
     Seattle Fault:  last small quake, probably Bremerton 1997? 5.0

Cascade volcanoes: associated with magma migration beneath and within cone
     variable activity, usually quakes come in swarms, 100's per day, then rather quiet
     depths from 0-10 km typically.  sizes usually quite small, less than 5
     special "harmonic" tremor caused by magma passing through fracture systems
          creates harmonics like blowing into a tube
     earthquakes under volcanoes very useful for tracking magma activity, eruptions.
 

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