We had the Landers earthquake in 1992 and it was a 7.4 in intensity. I don’t get how that wasn’t “ the big one”.
Was in Pasadena that morning, and even there the Landers quake was a scary one.
Landers was “a” big one. “The” big one would rip the San Andreas Fault near Fort Tejon the way it did in 1857. We’re talking 8.1 to 8.5 for that one.
We had the Landers earthquake in 1992 and it was a 7.4 in intensity. I don’t get how that wasn’t “ the big one”.
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I think they have determined that the “Big One” will be at least 9.0. I’m probably way off.
Imagine a 9.2 on the Richter scale. 100 times worse, or 2 orders of magnitude greater. All of these “little” quakes release a lot of tension that builds toward “ the big one.”
The reason the Landers quake wasn’t “the big one” is because it wasn’t directly underneath Los Angeles. I understand there is a fault (1) that runs directly under metro LA, (2) which is capable of storing the energy of a magnitude 8 quake, (3) which hasn’t slipped in a long time, and is overdue to do so. The Landers quake was a substantial energy release, but, not under LA and, more importantly, not in a way that released the energy stored underneath LA. The Northridge quake was much closer to the metro area than Landers was, but was a small earthquake relative to the amount of energy that is believed to still be underneath LA. If and when there’s a high-7s or low-8s quake smack within the LA area, major destruction and mass casualties are very likely to occur. *That* will be “the big one”.
(It’s not much consolation, but I have read that the LA area does not store enough energy for a magnitude 9 quake there ... but the Cascadia fault in the ocean beyond Washington State and Oregon does - and when that happens, there is going to be a 2004 Sumatra-scale, or a 2010 Japan-scale tsunami in the coastal regions of those states.
I’d guess “the big one” is a function of location, depth, and soils as much as magnitude (basically determining how much damage and casualties will occur). An 8.2 well away from population centers and in an area where the waves don’t “carry” well is “smaller”, by that definition, than a 7.5 on, say, the Hayward fault (not so often mentioned but VERY dangerous.)
The BIG one, that happens every several hundred years is above an 8.