Foreshocks and Swarms

 Other pages have discussed foreshocks as indicators of an impending earthquake.  Foreshocks are often stronger than expected (minor to moderate category), unusual or unexpected earthquakes that occur in or near a high earthquake risk area. 

Unfortunately you don't know an earthquake is a foreshock until a bigger quake happens.

Earthquake swarms are lots of smaller earthquakes within a geographically small area, usually on or near the same fault line. Like a foreshock, an earthquake swarm could also indicate an impending, larger earthquake.

The problem is foreshocks and swarms don’t come with a “prepare for a bigger one” warning. 

It's difficult to identify when in the future a bigger earthquake will rupture. Usually quakes identified as a foreshock happen within a few days preceding the main shock.

The reality of foreshocks and swarms is it’s hard to definitively state either is an indicator of a larger earthquake until after a larger quake strikes. In other words, foreshocks are labeled as such only after a larger quake happens. And earthquake swarms don't usually mean a bigger quake is coming...but sometimes they do.

The best part of earthquakes that could be foreshocks or earthquake swarms is they are a reminder to double-check your preparedness. Then, if a bigger earthquake occurs you conveniently had the preparedness reminder.

Earthquake aftermath


What I've found is as I've increased my preparedness the less I feel anxious about an earthquake swarm or other supposed quake predictor. These serve as reminders to check your preparedness.

After small and moderate earthquakes there tends to be an uptick in the number of people rushing to get prepared. The earthquake was a wake-up call that a bigger quake is coming and they feel anxious and unprepared.

And while any preparedness is better than none, too often when people try to prepare in an already stressful and anxious situation their judgment (and therefore preparedness) probably isn't as good as it could be. They're re-acting to the situation rather than being pro-active, which is what being prepared is all about.

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