Living in the pacific northwest gives us some familiarity with earthquakes. You've probably felt one or two right? But what about those large and disastrous quakes, like the one that hit Japan a couple years ago, or the one that created the Indian Ocean Tsunami in 2004? We're lucky that most quakes in Oregon are fairly small-scale. California bears the brunt of earthquake-related damage on the west coast and even the Seattle region gets hit more often than Portland.
Since the last 9.0 magnitude earthquake to hit Oregon was in 1700, there's worry that we are "due" for another mega-quake. How much truth is there to this concern?
There's a lot of misinformation floating out there about earthquakes. Here are some of the most popular myths and why they don't hold up to reality.
Myth: Can animals predict earthquakes?
A: There's plenty of anecdotal evidence for animals behaving strangely before and during earthquakes. Stories even date back to ancient Greek and Roman times. But animals do not exhibit consistent or reliable behavior when it comes to natural disasters like an earthquake. An animal low to the ground could potentially sense the early vibrations on an oncoming earthquake before we would. But this is not enough of a warning to be of use to us or to the animal.
Myth: Is a mega-quake likely to happen?
A: Not really. The magnitude of an earthquake is related to the length of a fault line. We don't know of any fault lines that could generate a 10.0 magnitude quake. The largest one ever recorded was a magnitude 9.5 in Chile in 1960. Sure, we can't rule out mega-quakes, but they are extremely unlikely.
Myth: Will California eventually fall into the Pacific Ocean?
A: The strike-slip earthquakes along the San Andreas Fault in California are a result of plate motion. The two plates (Juan de Fuca and North American) are moving past each other, not pulling apart. So California will not split in half or "fall into the ocean" but Los Angeles and San Francisco may someday wind up as neighbors.
Myth: Is there a region that doesn't experience earthquakes?
A: Small earthquakes can happen anywhere in the world. But Antarctica has the fewest of any continent.
Myth: Have there been more large scale earthquakes happening lately?
A: The frequency and magnitude of earthquakes across the world varies from year to year. The number of quakes with a magnitude 7.0 or higher has been above average in recent years but is still within the normal range. Remember that the two biggest earthquakes of the past century both happened in the 1960s - Chile in 1960 and Alaska in 1964.
Find more information at the US Geological Survey's website.