Couple o' articles:
Some on-topic articles I came across this morning:
Swarm of Small Quakes off Oregon Coast
"These earthquake swarms are associated with seafloor spreading,'' said Robert P. Dziak, an Oregon State oceanographer who works with NOAA at the university's Hatfield Marine Science Center in Newport.
"We suspect what happened was that magma pushed up into the crust and the lava may have broken the surface,'' Dziak said.
The swarm does not involve the big faults that are directly related to subduction, and are unlikely to generate quakes large enough for tsunami creation.
And another,
March is earthquake month and other 'shaky' facts
A deeper look reveals the true randomness of the events, dispelling also myths about "earthquake weather" and early morning quake frequency.