ISP 203B-Exam 2 questions and
answers
P and S waves under Dilatancy✔✔-Small cracks open in stressed rocks
-this reduces P-wave velocity (many get filled with subsurface water)
-S waves do not travel through fluids, therefore they travel a lot slower
-The s wave (denominator) decreases a lot faster than the P wave (numerator)
Effects of earthquakes and Landslides✔✔Effect of water on ground stability
Landslides, Glaciers and Volcanic products✔✔Dense material flows downslope
Hot material (air, volcanoes and magma)✔✔Rises
Cold material✔✔Sinks
Earthquakes and volcanoes✔✔Rocks crack under stress
Love waves✔✔-Structures are weaker to horizontal shaking
-Needs reinforcement
-Surface seismic waves that cause horizontal shifting of the earth during an
earthquake
Why is ground motion amplified by soft sediments when energy travels farther in
more solid crust?✔✔-Energy travels farther and is less damped out in a more solid
crust (upper lithosphere)
-Energy in the mid-continent travels farther than in the west because in the west the
crust is broken up and the lithosphere is hot
Earthquakes✔✔-Small earthquakes are more likely than large
-really large earthquakes are scarce
-earthquakes increase by a factor of 10 for each magnitude (Ex. a magnitude 8 is
10x more likely than a 9)
Earthquake predictions✔✔-Long term-Based on the presumption that large
earthquakes occur at more or less regular intervals
-Seismic gap theory- a region which has not experienced an earthquake in a long
time will have a "gap," in large seismicity when plotted on a map
-Short term- based on dilatancy on the premise that stress has to accumulate before
a major rupture can occur
Dilatancy related to observable precursory phenomena✔✔Dilatancy is the formation
of small cracks under stress caused by movements of the earths crust or due to
magmas accumulating beneath volcanoes
-Cracks can cause small earthquakes which can be recorded and located
-cracks allow gasses (volcanic or randon) to escape easier
-Cracks fill with water and water allows electricity to conduct more easily
, -Cracks take up space so the ground may need to respond by uplift or tilting
-Density might decrease (air and water are less dense than rock)
Tsunami and run-up heights✔✔-Tsunami are caused by anything that displaces a
significant amount of water
-Underwater reverse, thrust and normal earthquakes; cataclysmic underwater
volcanic eruptions, underwater collapse of a side of a volcano, pyroclastic flows into
shallow or small bays, other large underwater landslides, and bolide (meteorite)
impacts
-Run up heights are controlled by the overall amount of displaced water and the
geometry of the coastline
Implications of the Japan Earthquake for the US✔✔-Outer part of the plate boundary
zone was locked
-Outer part of the subduction zone closes to the trench axis appears to be locked
-Earthquakes become bigger by increasing faults
-In the Japan 2011 earthquake had large displacements in a smaller area which
caused a huge tsunami
Aseismic✔✔Not capable of generating earthquakes
"Episodic Tremor and Slip" ETS✔✔it appears that movement is occurring in small
jerky steps
Cinder Cone Volcanoes✔✔Very small, made dominantly cinder fragments. Very
loose piles of small fragments
Stratovolcanoes✔✔large constructs of lava, pryoclastic flows, ash, cinder, rocks.
They are welded together.
Domes✔✔Ooze out like toothpaste within craters or form fissures
Quantified Volcanoes✔✔-Volcano Explosively Index (VEI)
-Quasi-intensity, magnitude scale, (Quasi=qualitative descriptors and some
quantitative measures)
Thick layers of Ash✔✔-continental hot spot volcanoes have the highest silica content
magma
-tend to be even more explosive than those in subduction zones
-So if it is very thick ash more than likely it has very high silica
Volcanism at transform faults✔✔-very few volcanoes due to plates neither moving
apart nor coming together
-Most of the volcanoes tend to be small cinder cones
-form because they have small amounts of mixed composition at "pull-apart" basins
Divergent Boundary Volcanoes✔✔-form from crustal (lithospheric) extension
-Plates move apart and something has to fill the hole
answers
P and S waves under Dilatancy✔✔-Small cracks open in stressed rocks
-this reduces P-wave velocity (many get filled with subsurface water)
-S waves do not travel through fluids, therefore they travel a lot slower
-The s wave (denominator) decreases a lot faster than the P wave (numerator)
Effects of earthquakes and Landslides✔✔Effect of water on ground stability
Landslides, Glaciers and Volcanic products✔✔Dense material flows downslope
Hot material (air, volcanoes and magma)✔✔Rises
Cold material✔✔Sinks
Earthquakes and volcanoes✔✔Rocks crack under stress
Love waves✔✔-Structures are weaker to horizontal shaking
-Needs reinforcement
-Surface seismic waves that cause horizontal shifting of the earth during an
earthquake
Why is ground motion amplified by soft sediments when energy travels farther in
more solid crust?✔✔-Energy travels farther and is less damped out in a more solid
crust (upper lithosphere)
-Energy in the mid-continent travels farther than in the west because in the west the
crust is broken up and the lithosphere is hot
Earthquakes✔✔-Small earthquakes are more likely than large
-really large earthquakes are scarce
-earthquakes increase by a factor of 10 for each magnitude (Ex. a magnitude 8 is
10x more likely than a 9)
Earthquake predictions✔✔-Long term-Based on the presumption that large
earthquakes occur at more or less regular intervals
-Seismic gap theory- a region which has not experienced an earthquake in a long
time will have a "gap," in large seismicity when plotted on a map
-Short term- based on dilatancy on the premise that stress has to accumulate before
a major rupture can occur
Dilatancy related to observable precursory phenomena✔✔Dilatancy is the formation
of small cracks under stress caused by movements of the earths crust or due to
magmas accumulating beneath volcanoes
-Cracks can cause small earthquakes which can be recorded and located
-cracks allow gasses (volcanic or randon) to escape easier
-Cracks fill with water and water allows electricity to conduct more easily
, -Cracks take up space so the ground may need to respond by uplift or tilting
-Density might decrease (air and water are less dense than rock)
Tsunami and run-up heights✔✔-Tsunami are caused by anything that displaces a
significant amount of water
-Underwater reverse, thrust and normal earthquakes; cataclysmic underwater
volcanic eruptions, underwater collapse of a side of a volcano, pyroclastic flows into
shallow or small bays, other large underwater landslides, and bolide (meteorite)
impacts
-Run up heights are controlled by the overall amount of displaced water and the
geometry of the coastline
Implications of the Japan Earthquake for the US✔✔-Outer part of the plate boundary
zone was locked
-Outer part of the subduction zone closes to the trench axis appears to be locked
-Earthquakes become bigger by increasing faults
-In the Japan 2011 earthquake had large displacements in a smaller area which
caused a huge tsunami
Aseismic✔✔Not capable of generating earthquakes
"Episodic Tremor and Slip" ETS✔✔it appears that movement is occurring in small
jerky steps
Cinder Cone Volcanoes✔✔Very small, made dominantly cinder fragments. Very
loose piles of small fragments
Stratovolcanoes✔✔large constructs of lava, pryoclastic flows, ash, cinder, rocks.
They are welded together.
Domes✔✔Ooze out like toothpaste within craters or form fissures
Quantified Volcanoes✔✔-Volcano Explosively Index (VEI)
-Quasi-intensity, magnitude scale, (Quasi=qualitative descriptors and some
quantitative measures)
Thick layers of Ash✔✔-continental hot spot volcanoes have the highest silica content
magma
-tend to be even more explosive than those in subduction zones
-So if it is very thick ash more than likely it has very high silica
Volcanism at transform faults✔✔-very few volcanoes due to plates neither moving
apart nor coming together
-Most of the volcanoes tend to be small cinder cones
-form because they have small amounts of mixed composition at "pull-apart" basins
Divergent Boundary Volcanoes✔✔-form from crustal (lithospheric) extension
-Plates move apart and something has to fill the hole
