Earthquake Magnitude Scale Magnitude Earthquake Effects Estimated Number Each Year 2.5 or less Usually not felt, but can be recorded by seismograph. Millions 2.5 to 5.4 Often felt, but only causes ...

Why does Oregon participate in these earthquake drills? There are many reasons — including one "big one" — why residents ...

The Pacific Northwest is at risk for a mega-earthquake because of the Cascadia Subduction Zone. The region is primed for powerful quakes, with a particularly strong one called the Big One ...

I had experienced a couple of earthquakes ... scale. If you understand the logarithmic basis of the Richter Scale — that a 9.0 quake is ten times bigger than an 8.0 magnitude quake but 1,000 times ...