[boris]

"It's literally physically impossible to have a 10.5 quake in California, or anywhere else for that matter."

I am not a geologist but my understanding is that the scale is 'open ended'. Yes it is logarithmic but 'impossible'? I'd like proof. For example: if a five-mile-wide asteroid hit outside L.A. do you think a 10.5 reading might be recorded?

If I recall correctly, there have been massive events (100,000 years ago) which may have reached a much larger magnitude than the biggest we can imagine.

How large was the New Madrid quake?

What was the 'richter' magnitude of the Deccan Steps event, or the last time the Ring of Fire went off all at once?...

I do recall seeing somewhere that 14 would mean planetary disintegration...don't know if so.

--Boris

[John H K]

I did mention that with a really big asteroid you could perhaps get above 10.

Obviously no accurate measurement at the time, but certainly none of the New Madrid quakes were over 9, and I've seen a few papers revising the estimates downward under 8 so that they're no longer the largest continental US earthquakes.

The "Ring of Fire" has never gone off all at once, or anything close to that, so I'm not sure what you're talking about there.

The Deccan Traps were a large-scale volcanic event, but not an instaneous one, that outflow was still over a period of years.

The point is energy is a matter of physics, and you can't generate a 10+ without the sufficent fault surface to do so; You'd need a fault encircling the globe all going at once, and there's nothing like that, or remotely like that, on earth.

[Joe Hadenuf]

For example: if a five-mile-wide asteroid hit outside L.A. do you think a 10.5 reading might be recorded?

A five mile wide asteroid?

Boris, if one of those hit, outside LA, it would bounce Arkansas into the Atlantic Ocean. An asteroids at least 3/4 or a mile wide, could cause planetwide catastrophes.

The one suspected to have killed off the dinosaurs 60 million years ago, was an estimated 6 miles in diameter.

[Joe Hadenuf]

For example: if a five-mile-wide asteroid hit outside L.A. do you think a 10.5 reading might be recorded?

Agree, it would probably put it off the scale. lol.....