3 ms·

If you live in an earthquake zone you quickly learn what a 2, 4, 6 feel like. It is a gossip topic in your community like the weather.

zinekeller 5y ago
I think that although (estimated) magnitude is helpful, Japan's system also calculates the (estimated) intensity from the earthquake for your local area. Not always correct (but this tends to be rare), but usually within +/-1 of the Shindo scale (which is their local intensity scaling). Seems that ShakeAlert doesn't compute (yet, hopefully) the estimated intensity in your area.
Ancapistani 5y ago
If you live in an area with frequent earthquakes, yes. I live near the New Madrid. There aren't frequent earthquakes here at all, but historically when we do have one... it's a big one.
cgriswald 5y ago
This isn't my experience at all and I've lived in the Bay Area nearly half my life. I have a vague idea of what a mag 4 earthquake feels like, and that's about it.
- deleted 5y ago
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- antod 5y ago
  Yeah that makes sense, people talk about what magnitude x "feels" like, but they're really describing an earthquakes intensity rather than magnitude. You don't directly "feel" the magnitude. Any given magnitude quake is going to feel very different for people in different situations - eg how far away, how deep, soil conditions, how tall the building they are in etc... Magnitude is related to how much energy is released - useful for seismologists and records, while intensity is related to ground acceleration and subjective effects which is useful for structural engineers and the public caught in one. eg that 6.2 magnitude Christchurch quake mentioned elsewhere still managed to produce some of the highest ever recorded vertical ground accelerations despite releasing a tiny fraction of what a really big quake can do.
- kortilla 5y ago
  The Bay Area isn’t a frequent earthquake zone though

zinekeller 5y ago

I think that although (estimated) magnitude is helpful, Japan's system also calculates the (estimated) intensity from the earthquake for your local area. Not always correct (but this tends to be rare), but usually within +/-1 of the Shindo scale (which is their local intensity scaling). Seems that ShakeAlert doesn't compute (yet, hopefully) the estimated intensity in your area.

Ancapistani 5y ago

If you live in an area with frequent earthquakes, yes. I live near the New Madrid. There aren't frequent earthquakes here at all, but historically when we do have one... it's a big one.

cgriswald 5y ago

This isn't my experience at all and I've lived in the Bay Area nearly half my life. I have a vague idea of what a mag 4 earthquake feels like, and that's about it.

deleted 5y ago
[deleted]
antod 5y ago
Yeah that makes sense, people talk about what magnitude x "feels" like, but they're really describing an earthquakes intensity rather than magnitude. You don't directly "feel" the magnitude. Any given magnitude quake is going to feel very different for people in different situations - eg how far away, how deep, soil conditions, how tall the building they are in etc... Magnitude is related to how much energy is released - useful for seismologists and records, while intensity is related to ground acceleration and subjective effects which is useful for structural engineers and the public caught in one. eg that 6.2 magnitude Christchurch quake mentioned elsewhere still managed to produce some of the highest ever recorded vertical ground accelerations despite releasing a tiny fraction of what a really big quake can do.
kortilla 5y ago
The Bay Area isn’t a frequent earthquake zone though