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SEISMOLOGY. (All shook up.). Earthquakes can be frightening events . (Click on left image for short video.). Earthquakes. Usually happen near faults. (What are faults?) Many faults are near plate boundaries, but they can be anywhere and everywhere.
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SEISMOLOGY (All shook up.)
Earthquakes can be frightening events.(Click on left image for short video.)
Earthquakes Usually happen near faults. (What are faults?) Many faults are near plate boundaries, but they can be anywhere and everywhere. Over one million earthquakes per year (one every thirty seconds). Most are too small to be felt. But, there are several hundred powerful, damaging ones per year.
Faults – breaks or cracks in the crust where movement can occur.
The Richter Scale: • Measures the magnitude (amount of energy released). • 0-10 scale. • Devised by Charles Richter in 1935.
The Richter Scale is logarithmic.(What does that mean?) • It goes up exponentially. • Going up one whole number means a ten times more powerful quake! • So going up two whole numbers means a 100 times more powerful quake!!
Megathrust Earthquakes By far the most destructive of all
Megathrust quakes: • Happen at subduction zones. • Since 1900, all six 9.0 or greater quakes. • Can produce tremendous tsunamis (ex. Southeast Asia in 2004and Japan in 2011) • The Cascadia Subduction Zone is a very likely spot for a megathrust and a tsunami. • Click on image for short video (0:28)
The Cascadia Subduction Zone is a likely site for a megathrust quake and a tsunami. It’s happened there before. (Click for video 2:45)
But not to worry! Earthquakes or tsunamis can’t happen here.Right?
But we’re nowhere near a subduction zone, so the threat of a tsunami from a megathrust quake is impossible.But is there another way to trigger a tsunami?
Meet CumbreVieja, a volcano in the Canary Islands, just off the coast of Africa.
Some scientists predict that a landslide form a CumbreVieja eruption could produce not just a tsunami but an enormous MEGATSUNAMI. Good grief.(Click on image for a video 7:35)