Sumatra Earthquake Three Times Larger Than Originally Thought

[MadRat]

Sumatra Earthquake Three Times Larger Than Originally Thought

Evanston IL (SPX) Feb 08, 2005
Northwestern University seismologists have determined that the Dec. 26 Sumatra earthquake that set off a deadly tsunami throughout the Indian Ocean was three times larger than originally thought, making it the second largest earthquake ever instrumentally recorded and explaining why the tsunami was so destructive.
By analyzing seismograms from the earthquake, Seth Stein and Emile Okal, both professors of geological sciences in Northwestern's Weinberg College of Arts and Sciences, calculated that the earthquake's magnitude measured 9.3, not 9.0, and thus was three times larger.

These results have implications for why Sri Lanka suffered such a great impact and also indicate that the chances of similar large tsumanis occurring in the same area are reduced.

"The rupture zone was much larger than previously thought," said Stein.

"The initial calculations that it was a 9.0 earthquake did not take into account what we call slow slip, where the fault, delineated by aftershocks, shifted more slowly. The additional energy released by slow slip along the 1,200-kilometer long fault played a key role in generating the devastating tsunami."

The large tsunami amplitudes that occurred in Sri Lanka and India, said tsunami expert Okal, result from rupture on the northern, north-trending segment of the fault - the area of slow slip - because tsunami amplitudes are largest perpendicular to the fault.

Because the entire rupture zone slipped (both fast and slow slip fault areas), strain accumulated from subduction of the Indian plate beneath the Burma microplate has been released, leaving no immediate danger of a comparable ocean-wide tsunami being generated on this segment of the plate boundary.

However, the danger of a local tsunami due to a powerful aftershock or a large tsunami resulting from a great earthquake on segments to the south remains.

The analysis technique used by Stein and Okal to extract these data from the earth's longest period vibrations (normal modes) relied on results developed by them and colleague Robert Geller (now at the University of Tokyo) in their graduate studies almost 30 years ago.

However, because such gigantic earthquakes are rare, these methods had been essentially unused until records of the Sumatra earthquake on modern seismometers became available.

The largest earthquake ever recorded, which measured 9.5, was in Chile on May 22, 1960.

 

[Steeplerot]

:shocked: !9.3

 

[Crimson]

It wasn't an earthquake.. it was Israel and the Bush Administration testing new nukes... :roll:

 

[nageov3t]

wow. 9.3!? that's crazy :shocked:

 

[conjur]

Originally posted by: Crimson
It wasn't an earthquake.. it was Israel and the Bush Administration testing new nukes... :roll:

WTF is problem, troll? Get a life.




9.3...geez. I wonder if they'll adjust their calculations of the changes to the earth's rotation?

 

[Crimson]

Originally posted by: conjur

Originally posted by: Crimson
It wasn't an earthquake.. it was Israel and the Bush Administration testing new nukes... :roll:

WTF is problem, troll? Get a life.




9.3...geez. I wonder if they'll adjust their calculations of the changes to the earth's rotation?

Umm.. we had threads from the radical left in this forum saying it WAS a nuke.. did you post in that thread(s) saying they were trolls?

The answer is no.

 

[conjur]

Originally posted by: Crimson

Originally posted by: conjur

Originally posted by: Crimson
It wasn't an earthquake.. it was Israel and the Bush Administration testing new nukes... :roll:

WTF is problem, troll? Get a life.




9.3...geez. I wonder if they'll adjust their calculations of the changes to the earth's rotation?

Umm.. we had threads from the radical left in this forum saying it WAS a nuke.. did you post in that thread(s) saying they were trolls?

The answer is no.

Hmm...and why would that be, eh?

Perhaps I saw the thread as the troll thread it was and completely avoided it? Yes, I think that's the case. I'm surprised it wasn't locked from the outset.

This thread, however, is much different. Why don't you go back to your self-imposed departure from this place?

 

[GoPackGo]

Originally posted by: conjur

Originally posted by: Crimson

Originally posted by: conjur

Originally posted by: Crimson
It wasn't an earthquake.. it was Israel and the Bush Administration testing new nukes... :roll:

WTF is problem, troll? Get a life.




9.3...geez. I wonder if they'll adjust their calculations of the changes to the earth's rotation?

Umm.. we had threads from the radical left in this forum saying it WAS a nuke.. did you post in that thread(s) saying they were trolls?

The answer is no.

Hmm...and why would that be, eh?

Perhaps I saw the thread as the troll thread it was and completely avoided it? Yes, I think that's the case. I'm surprised it wasn't locked from the outset.

This thread, however, is much different. Why don't you go back to your self-imposed departure from this place?

See....now, I doubt a troll would cause such a great earthquake...however the Orcs, under the command of Lord Sauron...now thats a totally different matter.

 

[fornax]

9.3 is almost exactly 2 times stronger than 9.0, not three times. Spacedaily authors should review high-school math

 

[MadRat]

9.0 = 1x 9.0
9.1 = 2x 9.0
9.2 = 3x 9.0
9.3 = 4x 9.0

Right? So it would of had to have been 4 times more powerful right?

 

[Steeplerot]

bad sh1t no doubt. Hopefully this does not mean we have one coming on the west coast....

 

[Steeplerot]

Originally posted by: MadRat
9.0 = 1x 9.0
9.1 = 2x 9.0
9.2 = 3x 9.0
9.3 = 4x 9.0

Right? So it would of had to have been 4 times more powerful right?

1x9 would be a 9 < then a 9.1 9.0 would be your starting point here if I am not confused so 3x
A 9 is like your floor being ripped 6 feet violently sideways back and forth repeatedly if I recall. Imagine a 9.3 ack!

 

[Crimson]

Originally posted by: conjur

Originally posted by: Crimson

Originally posted by: conjur

Originally posted by: Crimson
It wasn't an earthquake.. it was Israel and the Bush Administration testing new nukes... :roll:

WTF is problem, troll? Get a life.




9.3...geez. I wonder if they'll adjust their calculations of the changes to the earth's rotation?

Umm.. we had threads from the radical left in this forum saying it WAS a nuke.. did you post in that thread(s) saying they were trolls?

The answer is no.

Hmm...and why would that be, eh?

Perhaps I saw the thread as the troll thread it was and completely avoided it? Yes, I think that's the case. I'm surprised it wasn't locked from the outset.

This thread, however, is much different. Why don't you go back to your self-imposed departure from this place?

Just to piss you guys off.. it appears to be working.

 

[fornax]

The Richter scale is a logarithmic scale. Log(2) = 0.3, therefore if A= 2B then log(A) = log(B)+0.3. If the earthquake was 9.3, and not 9.0, it was twice as strong.

Of course, all that is wrong if the scale is not log_base10 based, but I believe it is.

 

[shira]

Originally posted by: fornax
The Richter scale is a logarithmic scale. Log(2) = 0.3, therefore if A= 2B then log(A) = log(B)+0.3. If the earthquake was 9.3, and not 9.0, it was twice as strong.

Of course, all that is wrong if the scale is not log_base10 based, but I believe it is.

The Richter scale is no longer in common use. The numbers being quoted are based on the moment magnitude scale, considered more accurate. The moment magnitude scale is based on the area of the fault that ruptures in a quake.

 

[Genx87]

Hey did they ever determine if the sea floor really shifted 4000 feet up?
I had my doubts but was curious if anything ever came of it?

 

[miketheidiot]

Originally posted by: Crimson

Originally posted by: conjur

Originally posted by: Crimson

Originally posted by: conjur

Originally posted by: Crimson
It wasn't an earthquake.. it was Israel and the Bush Administration testing new nukes... :roll:

WTF is problem, troll? Get a life.




9.3...geez. I wonder if they'll adjust their calculations of the changes to the earth's rotation?

Umm.. we had threads from the radical left in this forum saying it WAS a nuke.. did you post in that thread(s) saying they were trolls?

The answer is no.

Hmm...and why would that be, eh?

Perhaps I saw the thread as the troll thread it was and completely avoided it? Yes, I think that's the case. I'm surprised it wasn't locked from the outset.

This thread, however, is much different. Why don't you go back to your self-imposed departure from this place?

Just to piss you guys off.. it appears to be working.

so you admit to being a troll?

 

[miketheidiot]

Originally posted by: Genx87
Hey did they ever determine if the sea floor really shifted 4000 feet up?
I had my doubts but was curious if anything ever came of it?

i heard 60 feet. 4000 is obsurd though, thats damn near a mile.

 

[Genx87]

i heard 60 feet. 4000 is obsurd though, thats damn near a mile.

That was my opinion as well. But somebody posted a link in the tsunami thread where shipping lanes were affected because they said the floor which used to measure 4000 feet was measuring 100 feet.

IMO if the floor moved up 4000 feet the wave would have been much larger than what we saw.

 

[Moonbeam]

I thunk a 6 was 30 times as strong as a 5 so a 9.3 would be 9 times as strong as a 9, no?

I guess it could also be 31 times depending.

 

[rahvin]

Originally posted by: shira

Originally posted by: fornax
The Richter scale is a logarithmic scale. Log(2) = 0.3, therefore if A= 2B then log(A) = log(B)+0.3. If the earthquake was 9.3, and not 9.0, it was twice as strong.

Of course, all that is wrong if the scale is not log_base10 based, but I believe it is.

The Richter scale is no longer in common use. The numbers being quoted are based on the moment magnitude scale, considered more accurate. The moment magnitude scale is based on the area of the fault that ruptures in a quake.

Not saying I remember my earthquake engineering course correctly but as I understood it the MMS is used, but for the common public a Richter "conversion" is made because that is what the public is accustomed to and in that case the scale is log 10 based and is roughly equivalent to the old Richter scale.