Unprepared: Will We Be Ready For The Megaquake In Oregon?

How Powerful Is A 9.0 Earthquake?

By Ryan Haas (OPB) and John Rosman (OPB)
March 9, 2015 4:31 p.m.

On March 11, 2011, Japan endured one of the worst natural disasters in its modern history. That was the day, a 9.0 earthquake shook off its coastline and inundated parts of the island nation with a tsunami.

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In parts of Japan, the devastation was sweeping, leveling entire city blocks.

Seismologists say there's a 37 percent chance a magnitude 8.0 or 9.0 earthquake could hit Oregon in the next 50 years.

While there are many lessons about earthquake preparation Oregon can take away from the Japan quake, one of the most basic is just how much more energy is released during a 9.0 compared to lesser magnitude earthquakes.

To help put that exponential difference in perspective, imagine that the energy released from a 3.9 earthquake is equal to a single grain of sand. On that scale, here would be the difference between different earthquake magnitudes:

  • Magnitude 3.9 = 1 grain of sand
  • Magnitude 4 = 3 grains
  • Magnitude 5 = 95 grains
  • Magnitude 6 = 3,052 grains (a small handful)
  • Magnitude 7 = 97,656 grains
  • Magnitude 8 = 3,125,000 grains (about 18 pounds)
  • Magnitude 9 = 100,000,000 grains (about 572 pounds)

Another way to compare the differences in various magnitudes is to look at the amount of energy released by each type of earthquake.

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