Quake Watch 2012

reply to post by sageturkey

Haha PM you had me there for a second, I thought to myself "Was I on the wrong side of the road?"

Great Heavens Sir, are you telling me that in some of the Colonies they do not drive on the right side of the road, which is of course the left? Dashed strange Sir, dashed strange.

PM, I agree that it was much busier last year - I'm sure that just being there had a huge effect on my perception of any increase in activity. I'm so fascinated (terrified?) by the place that I have to admit I had a bit of uneasiness. The little voice in the back of my head was saying "What are you doing here? Run away - Far away!

Not exactly Jellystone figure but ye may be interested in this: Seismicity 2012 so far – Earthquakes Mag 6+ to 31 Oct

Second big six today. Central America. ....aftershock of 7.4.


earthquake.usgs.gov...

reply to post by radpetey


Why are EMSC so predictable? They had 5.6 mb (~5.9 Mw) and now they have matched USGS at 6.2 Mw.

Where the Master leads the Sheep shall follow!

By the way "big six"? It was only 6.2 and Geofon think it was 6.1.

reply to post by PuterMan


Freakin' jack wagons!!

2nd.

reply to post by radpetey


2012-11-11 22:25:46, 14.373, -92.687, 4.8, 51.9, Offshore Chiapas. Mexico Map

Aftershock


Note to self: Remove the curly braces! They don't work.

EarthScope is reporting a 5.1mb for Hawaii.
How does that compare to M?

SOURCE: anf.ucsd.edu...

How reliable are they?
I noticed they listed a 3.2 off the coast of Oregon at 1:03:32 UTC yesterday,
that I couldn't find anywhere else.
WOQ

I am wondering if the 6.2 is new main shock.....???

Quite a few 4's right on it's tail.

earthquake.usgs.gov...

USGS has it at a 6.5 now:

earthquake.usgs.gov...

reply to post by deometer


No one else has changed however

Prov,Date/Time UTC,Latitude,Longitude,Magnitude,Depth(Km),Location
emsc,2012-11-11 22:15:04, 14.230, -92.031, 6.2, 60.0, Offshore Guatemala
usgs,2012-11-11 22:15:00, 14.163, -92.166, 6.5, 27.0, Offshore Guatemala
gfzp,2012-11-11 22:15:00, 14.250, -92.240, 6.1, 10.0, Nr. Coast Of Chiapas. Mexico

I see the USGS appears to have reinstated the moment tensors on the site technical pages which had not been working. I was told they were to be removed and I complained bitterly. Did this have the desired effect or is this just a temporary reprieve?

There were surprisingly few aftershocks of the 7.7 on the 8th, so this 6.5 is no surprise now

interactive map showing the plots of the data from INETER - Instituto Nicaraguense de Estudios Territoriales, 02/11/2012-12/11/2012, the full opacity icons are those events AFTER the 7.7

* Note, ignore the UTC Time on the tags, its actually Local time, I forgot to change the fields before uploading it. can't be bothered now, just wanted to see where these were thats all.

reply to post by PuterMan

Good work, you can probably take some credit for that. Thing is if no one tells them how useless they are they think they are marvelous

for those interested in following the aftershock sequence for the Burma 6.6, their neighbor does a pretty good job of catching Burmese quakes.
www.seismology.tmd.go.th...

As you can see further down the list they go down to Mag 1, so there are bound to be more aftershocks of a smaller magnitude in the next few days.

Interactive map of them so far (3 more than the main global networks)

* Note, these ARE in UTC

I wanted some help distinguishing the following events: Main quakes, aftershocks and swarms.
I know most of you are aware of this info, but for those who are new to monitoring seismic activity, like me it would help to know for sure what we are looking at.

I did some research and found the following. Those with experience please add or correct this information.

Earthquake vs Aftershocks

Q. How Can You Tell The Difference Between An Earthquake And Aftershocks? A. The earthquake sends out the strongest shock waves. The aftershocks are what occur later and in the same place along the fault line. As time passes, the aftershocks become less strong. Scientist predicted that the aftershocks from the October 17, 1989, earthquake would continue for one to two years, though many may have been too small to feel.

Swarm

Earthquake swarms are events where a local area experiences sequences of many earthquakes striking in a relatively short period of time. The length of time used to define the swarm itself varies, but the United States Geological Survey points out that an event may be on the order of days, weeks, or months.[1] They are differentiated from earthquakes succeeded by a series of aftershocks by the observation that no single earthquake in the sequence is obviously the main shock. Earthquake swarms are one of the events typically preceding eruptions of volcanoes.

Can aftershocks turn into a swarm?


Thank you

Source
Source

5.9 mb Japan (Nowhere near land )

Magnitude mb 5.9
Region IZU ISLANDS, JAPAN REGION
Date time 2012-11-12 11:15:08.0 UTC
Location 29.72 N ; 138.01 E
Depth 483 km
Distances 600 km SE Osaka (pop 2,592,413 ; local time 20:15:08.5 2012-11-12)
557 km S Hamamatsu (pop 605,098 ; local time 20:15:08.5 2012-11-12)
476 km SE Nachikatsuura (pop 18,712 ; local time 20:15:08.5 2012-11-12)

www.emsc-csem.org...

Theoretically ~6.1 Mw. We shall see.

[Map]


You have to love these people. Now it is a 5.1 !!

HOWEVER JMA have it as 5.8
2012-11-12 11:16:00, 29.600, 138.400, 5.8, 510.0, Torishima Kinkai [Map]

5.8ML is about the same in Mw so closer to the original EMSC estimate than now. Potsdam say 5.3 M - really useful scale that tells you nothing much. geofon.gfz-potsdam.de...

reply to post by Observationalist

I wanted some help distinguishing the following events: Main quakes, aftershocks and swarms.

From your sources:

The earthquake sends out the strongest shock waves. The aftershocks are what occur later and in the same place along the fault line. As time passes, the aftershocks become less strong. Scientist predicted that the aftershocks from the October 17, 1989, earthquake would continue for one to two years, though many may have been too small to feel.

I would say that is a little misleading. "and in the same place along the fault line" makes it sound as if they are all on one spot which of course they are not. Whilst many aftershocks will occur at either end of the fracture, they also occur around the area of the fault fracture. The distribution will be in accordance with the Coulomb stress analysis - a method of determining where the stress from an earthquake has been transferred. This is not necessarily exactly along the line of the fault and it depends on the type of event that occurred. (Thrust/slip/normal etc)

Aftershocks occur from the time of the main event until the background seismicity has returned to normal levels, which actually means that the precise time that events cease to be aftershocks is not easy to determine. It could be months or years after an event, even as much as 10 years after from the very largest events.

It is stated often that you can expect an earthquake of 1 magnitude less than the main event as an aftershock. Personally I do not agree with this statement. In my opinion aftershocks can be close to .5 magnitude from the original shock in events less than Magnitude 7, but that very large events from my research rarely if ever have events of greater magnitude than 1 magnitude separation, and often it is greater. ETA that is confusing! The largest shock after a major quake is normally more than 1 magnitude lower than the main shock.

Here is the Japan sequence - dates in reverse order

Prov,Date/Time UTC,Latitude,Longitude,Magnitude,Depth(Km),Location
usgs,2011-07-10 00:57:12, 38.040, 143.287, 7.0, 23.0, Off E. Coast Of Honshu. Japan
usgs,2011-04-07 14:32:41, 38.253, 141.639, 7.1, 49.0, Nr. E. Coast Of Honshu. Japan
usgs,2011-03-11 06:25:50, 38.106, 144.553, 7.1, 19.7, Off E. Coast Of Honshu. Japan
usgs,2011-03-11 06:15:40, 36.179, 141.172, 7.9, 39.0, Nr. E. Coast Of Honshu. Japan
usgs,2011-03-11 05:46:23, 38.322, 142.369, 9.1, 32.0, Nr. E. Coast Of Honshu. Japan
usgs,2011-03-09 02:45:20, 38.424, 142.835, 7.2, 32.0, Nr. E. Coast Of Honshu. Japan

The other thing you should be aware of is that very deep earthquakes, ~400+ km tend to have few if any (detected?) aftershocks.

Earthquake swarms are events where a local area experiences sequences of many earthquakes striking in a relatively short period of time. The length of time used to define the swarm itself varies, but the United States Geological Survey points out that an event may be on the order of days, weeks, or months.[1] They are differentiated from earthquakes succeeded by a series of aftershocks by the observation that no single earthquake in the sequence is obviously the main shock. Earthquake swarms are one of the events typically preceding eruptions of volcanoes.

I guess that about sums it up! Again a swarm has ended when the background seismicity returns to 'normal'

Can aftershocks turn into a swarm?

In the strictest sense no they cannot, but you may have the situation where a larger earthquake in a volcanic area sets off a swarm so it would be difficult then to differentiate between aftershocks and swarm.

reply to post by PuterMan

Thanks PuterMan, I knew there was more to it.
I do really appreciate you and muzzy 's faithful monitoring of all these EQs.

reply to post by Observationalist


Ahhh a subject I have spent years researching

as well as what Puterman said, there are also aftershocks that have their own aftershocks
Some recent examples;
take the Canterbury, NZ Series the longest running and largest numbered earthquake aftershock series recorded in New Zealand.
There have been 4 main strong events, which had their own sub series of aftershocks, these have been named Darfield, Port Hills, Taylors Mistake and New Brighton.
Each mag6 aftershock had its own series of aftershocks (while the previous ones were still going on as well)

and the Emilia-Romagna, Italy Series where the difference between the first main quake 5.9 and the next big aftershock, a 5.8 nine days later was just 0.1 magnitude, so could possibly be called a swarm?, each one had its own series of aftershocks, as can be seen it the colour coded map.

Foreshocks are even tougher to define, as no one knows they are "foreshocks" or a "swarm of earthquakes" until a/the main quake happens. A classic example of foreshocks/main shock/aftershock series is the Brawley,Ca Series which I posted a few maps of here on ATS, (but just realised I never published on my own blog.)

In fact, that eqarchives is all about swarms and aftershocks

As far as when are the aftershocks over?
well if returning to background levels is the definition then the Canterbury quakes are still "aftershocking" after 2 years, there are still one or two quakes there every day, prior to Sept 4th 2010 the area around Darfield to Pegusus Bay had zero earthquakes over the previous 115 years, so in that case "background levels " may be 0 or it could be a new "average" per day/month/year will have to be defined.

"triggering" is another facet of the earthquake scene that little is known about.
There is a series that happened along the NZ Fiordland coast over a period of 21 years
It is speculated that due to the proximity in space and time;
the 2009 Dusky Sound 7.6Mw
may have been triggered by the
2007 double 6.7 and 6.2 Milford Sound quakes
and those may have been triggered by the
2003 Secretary Island 6.3Ms
and that may have been triggered by the
1993 Secretary Island 6.8 Mw
may have been triggered by the
1989 Doubtful Sound 6.4Mw
and probably more prior to that
and that all those subduction type quakes culminated in shifting the lower west coast of the South Island south west and eventually ripped Canterbury apart at Darfield.
No one knows for sure though

ET: I've never done a full story on that Fiordland triggering series, but you can see them all on this Fiordland focused NZ Mag6+ interactive map
Some of the aftershocks of each of those I mention is on the individual years on NZ Historical Earthquakes 5+ 1930-2011 but they are not interactive. I lost the KML files since then

Magnitude 6.0 6.2 - Gulf Of Alaska

Location in Google Maps

• Date-Time: Monday, November 12, 2012 @ 20:42:16 UTC
  
• Earthquake location: 57.854°N, 142.914°W,
  
• Earthquake depth: 15.5 km
  
• Distances:
  264km (164mi) S of Cape Yakataga, Alaska
  499km (310mi) W of Juneau, Alaska
  555km (344mi) SW of Whitehorse, Canada
  561km (348mi) SE of Anchorage, Alaska
  571km (354mi) SE of Knik-Fairview, Alaska
  
• Event ID: ak10598710
  

Derived from Event Data Source: USGS
Powered by QVSData


EMSC

Magnitude mb 5.8
Region GULF OF ALASKA
Date time 2012-11-12 20:42:14.0 UTC
Location 57.75 N ; 142.59 W
Depth 2 km
Distances 1585 km NW Vancouver (pop 1,837,969 ; local time 12:42:14.3 2012-11-12)
533 km SE Anchorage (pop 276,263 ; local time 11:42:14.3 2012-11-12)
480 km W Juneau (pop 31,796 ; local time 11:42:14.3 2012-11-12)

GFZ 6.3

geofon.gfz-potsdam.de...

Revised (6.0 -> 6.2): 6.2 earthquake, 246km S of Cape Yakataga, Alaska. Nov 12 10:42 at epicenter

2012-11-12 20:42:14 UTC
2012-11-12 10:42:14 UTC-10:00 at epicenter
2012-11-12 15:42:14 UTC-05:00 system time
Location
57.852°N 142.907°W depth=0.4km (0.2mi)

Nearby Cities
246km (153mi) S of Cape Yakataga, Alaska
502km (312mi) W of Juneau, Alaska
543km (337mi) SE of Anchorage, Alaska
548km (341mi) WSW of Whitehorse, Canada
553km (344mi) SE of Knik-Fairview, Alaska

reply to post by kennvideo

0.4km (0.2mi)

Tsunami amyone?

No, no tsunami but look at the magnitude

000
WEPA42 PHEB 122049
TIBPAC

TSUNAMI BULLETIN NUMBER 001
PACIFIC TSUNAMI WARNING CENTER/NOAA/NWS
ISSUED AT 2049Z 12 NOV 2012

THIS BULLETIN APPLIES TO AREAS WITHIN AND BORDERING THE PACIFIC
OCEAN AND ADJACENT SEAS...EXCEPT ALASKA...BRITISH COLUMBIA...
WASHINGTON...OREGON AND CALIFORNIA.

... TSUNAMI INFORMATION BULLETIN ...

THIS BULLETIN IS FOR INFORMATION ONLY.

THIS BULLETIN IS ISSUED AS ADVICE TO GOVERNMENT AGENCIES. ONLY
NATIONAL AND LOCAL GOVERNMENT AGENCIES HAVE THE AUTHORITY TO MAKE
DECISIONS REGARDING THE OFFICIAL STATE OF ALERT IN THEIR AREA AND
ANY ACTIONS TO BE TAKEN IN RESPONSE.

AN EARTHQUAKE HAS OCCURRED WITH THESE PRELIMINARY PARAMETERS

ORIGIN TIME - 2042Z 12 NOV 2012
COORDINATES - 57.7 NORTH 142.8 WEST
DEPTH - 10 KM
LOCATION - GULF OF ALASKA
MAGNITUDE - 6.5

EVALUATION

NO DESTRUCTIVE WIDESPREAD TSUNAMI THREAT EXISTS BASED ON
HISTORICAL EARTHQUAKE AND TSUNAMI DATA.

THIS WILL BE THE ONLY BULLETIN ISSUED FOR THIS EVENT UNLESS
ADDITIONAL INFORMATION BECOMES AVAILABLE.

THE WEST COAST/ALASKA TSUNAMI WARNING CENTER WILL ISSUE PRODUCTS
FOR ALASKA...BRITISH COLUMBIA...WASHINGTON...OREGON...CALIFORNIA.

On the USGS site it is now giving 6.2 mb so ..... Mag 6.1 anyone?