As it turns out, the earthquake this morning was actually the second highly unusual thing to happen today. The first occurred late last night, as I was going into the bathroom one last time before going to sleep. A couple steps into the bathroom and I stepped into something wet. While having the floor of your bathroom wet for no apparent reason is unusual enough, I was more concerned with the smell: a faint smell of ammonia, and another smell I knew I had encountered before, though I couldn't think exactly what it was.
After I confirmed that the liquid was what was producing the smell, I hobbled back to my room (trying to avoid getting whatever it was on the floor as much as possible) to grab my glasses, and had another look. A fair amount of the floor was wet with several ounces or so of a liquid that was in some places clear, in other places milky white.
After tracing it under the sink, I found what seemed to be the cause: a can of insecticide. The entire can was wet, though not much that wasn't right near where it was, so it didn't look like an explosion (though there sure was a lot of the stuff on the floor). I didn't try removing the cap (for obvious reasons), but I'm thinking the spray nozzle might have exploded and the cap prevented the stuff from getting all over the cabinet under the sink. Ultimately, I wrapped it in a couple plastic bags and threw it in the trash, and wiped up all the stuff on the floor (probably wouldn't hurt to mop the floor with soap and water, either).