Chapter 5-8 Flashcards
Which of the following is not a cause of tsunamis?
underwater strike-slip earthquakes
Along which type of plate boundaries do we not find tsunamis?
Transform
Prior to a subduction zone earthquake, what would you expect to occur to the crust on the overriding plate?
the crust will rise (bulge upwards)
The average speed of tsunami waves in the deep ocean is most similar to which of the following?
Jet airline
Which wave of a major tsunami is most likely to be the highest? (Hint: see the figure in the textbook that shows the tide gauge from a tsunami).
Third or fourth
What happens to tsunami waves as they reach the shoreline?
their amplitude (height) increases and wavelength decreases
True or False: Tsunamis, sometimes called “tidal waves” are caused by tides.
False
What is a volcanic flank collapse?
a sudden landslide of the side of a volcano not associated with an eruption
True or false: Tsunamis occur only in oceans.
False
Which type of basaltic lava flow has a fairly smooth, unfragmented, ropy surface?
pahoehoe
Which type of basaltic lava flow has its surface covered with sharp-edged, angular blocks and rubble
Aa
small basaltic cones built during one, short, eruptive episode (enter the letter only)
Cinder Cones
large, fairly steep-sided cones composed of lavas and pyroclastic layers (enter the letter only).
Stratovolcanoes
massive, gently sloping volcanoes built of successive, basaltic lava flows (enter the letter only)
Shield volcano
The recent (geologically) volcanic activity in Yellowstone National Park is ________.
related to intraplate, hot spot volcanism
A basalt magma typically erupts in what form?
Lava flow
A rhyolite magma typically erupts in what form?
Fine ash
The ________ ocean basin is rimmed by the most subduction zones.
Pacific
Consider the Volcanic Explosivity Index. How long would you expect a volcanic eruption like Mt. Saint Helens to last?
More than 12 hours
Felsic Descripition
High Silica Content - 70% Color - light tan, grey, pink Weight - lightest Cooling temp: 700-900 degrees C CRAZY EXPLOSIVE 🔥🔥🔥🔥 Example: Rhoylite
Intermediate Description
Silica Content: 60% Intermediate Color: dark gray Weight: andesite Cooling temp: 900-1100 degree C Example: Andesite
STILL EXPLOSIVE BUT NOT AS BAD AS FELSIC
Mafic Description
50% low silica Content Black More dense 1100-1200 degree c Quiet eruption
Viscosity
How thick of thin substance is
Pyropalstic flow
Ash Fall, has to be mixed with rocks
