Tsunami and Surges
Describe how tsunami form and how they are detected.
Earthquakes, volcanic eruptions, meteor impacts, landslides, icebergs falling
DART System: measures pressure changes on seafloor, communicates info
to warning centres
Explain how a tsunami differs from more common, wind-driven ocean waves.
Short wavelength and period, breakers arrive and recede quickly
Tsunami: ultralong walvelength and period, huge mass of water comes
ashore for several minutes
Explain why tsunami come ashore so violently.
Vertical fault motion, energy transfer to water column, common in large
Identify tsunami warning signs, and know how to respond.
First wave may not be biggest
Trough may arrive first, watch for receding sea level Describe the risks from a tsunami for the coast of British Columbia, especially
one resulting from a megathrust earthquake.
Liquefaction, buried sand/mud volcanoes
Define wave breaking, and determine when a wave will break.
Breaking waves = energy release
Waves become unstable, too high for wavelength
Wave energy becomes surf energy, turbulent mass of water rushing onshore
As waves shoal (move into shallower water), characteristics change
o Speed, wavelength decreases
o Height, steepness increases
o Period same
o Orbitals flatten, become elliptical
Explain the differences between surging, plunging, and spilling breakers.
Spilling: small gentle spilling breakers, wave energy lost over a wide area
Plunging: steep slope, large violent,