Quake Swarm

Last Saturday I went hiking in the Loma Linda Hills just south of the city. Around one o'clock I was sitting on a hill reading, when the earth began to shake. I've always thought I would feel safer out in the open during an earthquake but even being up on a hill could be a frightening experience. The entire hill felt like Jell-O and it seemed that if the hill shook much harder the whole thing could disintegrate. It turns out that Saturday's quake was 4.1 on the Richter scale. The earthquake on Saturday would be the beginning of a week of almost daily temblors. Today was the most extreme day yet with three earthquakes in a row, each above 3.0, just before noon. Southern California is known for its earthquakes but during the last week I've felt as many as I have in the last two and a half years of med school.

They're calling this current spate of earthquakes an "earthquake swarm" and you can get a nice visual of the "swarm" on the map I copied from here below. In the map you can see the city of Loma Linda where I live and go to school and the swarm of earthquakes off to the southeast:

Yellow circles indicate earthquakes from the past week, blue circles from the past day and the red circle is an earthquake which had occurred in the preceding hour. The bigger the circle, the stronger the earthquake. The majority of these quakes are "micro-earthquakes" and can't be felt but a good number of them have been big enough to shake things up a bit.