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Have you been in an earthquake before? I remember sleeping during a quake and then waking up right before the main shock hit. I’m not sure what woke me up, it c

Have you been in an earthquake before? I remember sleeping during a quake and then waking up right before the main shock hit. I’m not sure what woke me up, it could’ve been a preliminary shock, but I very vividly remember being jolted awake right before the earthquake wave hit. It’s entirely possible that an electromagnetic wave precedes a shock, but it’s unlikely that there are significant waves hours beforehand if there’s actually a causal relationship to the movement of the plates themselves. It would be far more likely that the EM pulse happens with slightly faster propagation than the kinetic pulse (like milliseconds, not hours).

brodie 7y ago
I’ve experienced a number of them and never felt anything leading up to them. The last decent one I can remember was a few years ago around maybe 2 or 3 AM and made my apartment roll back and forth. The rolling woke me up but my partner slept through it. And I tried not to panic so they could just sleep through it, hoping it would end soon. Also, we didn’t have anything hanging or that could easily fall onto our bed in the bedroom so I think staying in the bed was an okay move. I live in a single family home now even higher up the Twin Peaks area of SF so who knows how this house will handle the next one. Hopefully it won’t be too bad. At least the ground is solid and not considered a liquefaction zone. And my new neighbors seem to have some kind of thing going on where they stock first aid supplies for first responders in disasters which seems nice and thoughtful. Though I just don’t understand why SF won’t use our missile warning system for earthquake warnings. Seems like they could make a special earthquake tone and warn everyone if one happens in another city and is heading our way. Even seconds of warning would be so helpful. Could be the difference in being able to jump under a table or desk vs. getting crushed by falling stuff.
asdfman123 7y ago
There are three types of waves that travel through the earth's crust during an earthquake at different speeds: primary, secondary and surface waves, which arrive in that order. Perhaps one of the first two waves woke you up, and then the surface wave is what "felt" like an earthquake to you. In fact, earthquake warning systems detect P-waves early, send out alarms, and give people a few seconds to stop subways and get outside before the surface waves roll in. It's not the same as earthquake prediction, though.
- saltcured 7y ago
  Do you how fast these waves travel versus sound in the atmosphere? Or, how these waves themselves might sound qualitatively when they shake nearby structures in the air? On more than one occasion, I think I've anticipated an earthquake based on sound. I can only describe it like an approaching but amorphous activity, a bit like when large flocks of birds take to flight over an open field or when a wind gust goes through a forest. I think I've noticed this sound only with relatively nearby epicenters (5-25 miles). The very distant ones usually seem more silent and my first recognition is the jiggle and displacement, or perhaps the creaking sounds of the surrounding structure if I am indoors.

brodie 7y ago

I’ve experienced a number of them and never felt anything leading up to them. The last decent one I can remember was a few years ago around maybe 2 or 3 AM and made my apartment roll back and forth. The rolling woke me up but my partner slept through it. And I tried not to panic so they could just sleep through it, hoping it would end soon. Also, we didn’t have anything hanging or that could easily fall onto our bed in the bedroom so I think staying in the bed was an okay move. I live in a single family home now even higher up the Twin Peaks area of SF so who knows how this house will handle the next one. Hopefully it won’t be too bad. At least the ground is solid and not considered a liquefaction zone. And my new neighbors seem to have some kind of thing going on where they stock first aid supplies for first responders in disasters which seems nice and thoughtful. Though I just don’t understand why SF won’t use our missile warning system for earthquake warnings. Seems like they could make a special earthquake tone and warn everyone if one happens in another city and is heading our way. Even seconds of warning would be so helpful. Could be the difference in being able to jump under a table or desk vs. getting crushed by falling stuff.

asdfman123 7y ago

There are three types of waves that travel through the earth's crust during an earthquake at different speeds: primary, secondary and surface waves, which arrive in that order. Perhaps one of the first two waves woke you up, and then the surface wave is what "felt" like an earthquake to you. In fact, earthquake warning systems detect P-waves early, send out alarms, and give people a few seconds to stop subways and get outside before the surface waves roll in. It's not the same as earthquake prediction, though.

saltcured 7y ago
Do you how fast these waves travel versus sound in the atmosphere? Or, how these waves themselves might sound qualitatively when they shake nearby structures in the air? On more than one occasion, I think I've anticipated an earthquake based on sound. I can only describe it like an approaching but amorphous activity, a bit like when large flocks of birds take to flight over an open field or when a wind gust goes through a forest. I think I've noticed this sound only with relatively nearby epicenters (5-25 miles). The very distant ones usually seem more silent and my first recognition is the jiggle and displacement, or perhaps the creaking sounds of the surrounding structure if I am indoors.