Just had an earthquake--4.8 from Alaska Earthquake Center, and originally a 4.9 from USGS. Shook the house and rocked the file cabinet, but no noted damage. It appears to be an aftershock of the quake we had a couple years ago.
That's no fun. I live about 5 miles from the epicenter of that 5.8 we had here in August 2011 that trashed stuff from Louisiana to Canada. I'm glad things are OK, Don. It's unnerving.
I looked this up when we had that 2011 quake to find out what was an aftershock and what was a brand new event. I can't find any reliable source right now that I would want to pass on. The USGS website says: Depending on the size of the mainshock, aftershocks can continue for weeks, months, and even years after the mainshock! It can make you paranoid.
When I went through a bad earthquake, we had aftershocks for about six weeks. After a while, nobody got excited about them. It was "ho-hum, another tremor...."
@Don Alaska What sort of construction is your house built of? The big quake centered about Sylmar, CA in the 70s caused my uncle's masonry chimney to fall over, but the frame house was OK. He and my aunt happened to be in Vegas that day, and a huge glass mirror above their headboard, on the wall, crashed down onto their bed. It might have seriously injured them if they had been home asleep. Frank
We had an earthquake in Millinocket a couple of weeks ago but it was a 1.8, probably noticed only by a piece of equipment somewhere. Then again, I was in California for twelve or thirteen years and didn't notice any of the larger ones we had there, either.
I seldom feel anything under a 5 or 6, but my wife is more sensitive. We are also atop a glacial moraine or something that absorbs some of the energy.
When we had that 5.8 here in 2011, there were aftershocks for a couple of years. I got good at estimating their intensity. The USGS website has a place called "Did you feel it?" where you can report your current earthquake experiences. I would log on and say "Felt like a 3.2 to me." A few hours later the official stats would get posted: 3.2 It's a skill I really had never wanted to acquire. I am pretty close to that epicenter, and could hear the aftershocks coming from off in the distance. They would get louder and louder as the wave approached, like a herd of buffalo, then the house would shake a bit and the herd would stampede off in the distance. I would go out on my deck just to listen. The other thing I learned is that magnitude is felt differently in different regions, depending on their geology. That 5.8 here in Virginia caused damage from Louisiana into Canada because the east coast bedrock transmited the shock waves so well. A 7.0+ on the west coast doesn't really radiate out very far because the soil is looser...but it transmits deeper since there is no solid layer to stop it.
When I was in California, my brother called me from Michigan to ask if I was okay. It seems that I was living on an earthquake fault and there had been an earthquake that was in the national news. However, I wasn't watching the news so I hadn't noticed.
The last earthquake I felt was miles away but still nearly shook me out of bed. My contractor lives where the epicenter was, and we simultaneously texted each other at 1:30 or 2 am, or whatever it was, making sure each was okay. We were.
I may have posted this before: There was a lot of damage due to that 5.8 Houses crumbled. Brick walls collapsed at historic churches. I know people who lived at the epicenter. One of them had no damage whatsoever while his neighbors' houses were unsafe to live in. After the quake, the USGS came out and installed a ton of sensors in the county. After recording a few aftershocks, they informed the guy that his house was floating on its own plate, unattached to (and unaffected by) the surrounding geology. Stuff around him would quake, and his sensors registered nothing (or very little.) Fascinating stuff.
Earthquakes are felt differently based not only on proximity to epicenter, but depth of the quake. Deep ones don't seem to cause much damage, but shallow quakes can really rock and roll. We had a 7.9 to the south, but it was so deep, it was hardly felt at all, and we had one of approximately the same intensity at the same distance that caused all kinds of shaking. The 7.1 that hit a good bit closer and only 29 miles down that caused widespread destruction. We live very near to a fault, but it hasn't moved in a while. It is hard to avoid earthquakes in this part of Alaska.