Quake Watch 2012

Well there is your "aftershock" with one less unit of magnitude
Didn't take too long.

As some of you know we just got a 6.3 in Oaxaca.I am in Mexico City.I live on the 4th floor of an apartment building and I felt a good shake.This one didn´t last as long as the 7.4 we got a few weeks ago but it good enough to get my heart racing.I am from Canada and I am really not used to feeling earthquakes on a regular basis.

reply to post by angelchemuel

I have noticed over the last week, that much more than normal EQ's reported on EMSC are at a greater depth.
Question...take an eq of say 5.2 at 230 km does that mean at 230km it is far bigger if the seismograph was at that depth? Also ar rgar depth are we looking at magma movement.

As Hellas correctly states the magnitude is at the hypocentre, but it makes no difference if the earthquake is 600km deep or 1km deep the magnitude is the same. What changes is the effect of the earthquakes, i.e. the shaking on the Mercalli scale and that is dependent on a combination of depth and geological formations.

Magma movement, if you are meaning as in volcanoes, no. You only get earthquakes that deep in subducting lithosphere, basically before the cold ocean slab has heated enough to become pliable at which point earthquakes are no longer possible. It would be unusual to get volcanic quakes below 30km, in fact it would be very rare I believe.

If you look at page 16 of this PDF file you will see a table of mean depths of volcanic swarms.

The document is a bit old - GLOBAL VOLCANIC EARTHQUAKE SWARM DATABASE 1979-1989 rather like me, but still relevant, I hope like me!

reply to post by November5th


Magnitude 6.0 anyone? Got one going cheap here.

USGS WPhase Moment Solution
OAXACA, MEXICO

12/04/02 17:36:43

Epicenter: 16.476 -98.286
MW 6.0

USGS/WPHASE CENTROID MOMENT TENSOR
12/04/02 17:36:43.00
Centroid: 16.576 -98.182
Depth 11 No. of sta: 37
Moment Tensor; Scale 10**18 Nm
Mrr=-1.02 Mtt= 0.98
Mpp= 0.04 Mrt= 0.66
Mrp= 0.25 Mtp= 0.05
Principal axes:
T Val= 1.19 Plg=17 Azm=353
N = 0.07 7 260
P = -1.26 71 147

Best Double Couple:Mo=1.2*10**18
NP1:Strike= 95 Dip=29 Slip= -73
NP2: 257 63 -98

Need to wait for the centroid but based on this I would guess this is going to be relegated to the second division.

Here is a centroid. GeoAzur. Looks like a reduction to 6.1 is in order. EMSC have 6.1mb. I am wondering if that should be Mw.

Geofon have it at 6.0 Mw.

reply to post by PuterMan


Like I said before this quake was a good fast shake that came from knowhere and lasted for about 15 seconds.The one a few weeks ago,started with slow shaking and increased into much stronger shaking.And it lasted for what appeared to be over a minute.Mind you your when you feel an earthquake this strong, your equilibrium gets thrown off and you don´t know what´s going.I swear I have felt a few aftershocks today but nothing else has shown up on USGS.

reply to post by November5th


What news of damage or loss of life from the area?



A yellow fatality alert which is as many as 100 fatalities.

earthquake.usgs.gov...

reply to post by November5th


This is from earthquake-report.com...

Update : The Mexican seismological agency has increased his initial Magnitude to 6.0. Since the mainshock today, 2 aftershocks of resp. 4.6 and 4.7 have been listed (normal)

update to post by PuterMan


The economic level has just been reduced to Yellow.

Many of the links are down. I believe the pages are being recalculated for a lower magnitude.


No recalc yet.

USGS Global CMT Project tensor in @ Mw 6.0 yet STILL they have not changed the original.

earthquake.usgs.gov...

reply to post by MamaJ


Thanks for the info.For awhile I was thinking I am going quake-crazy.As far as I know there hasn´t been any signifcant damage or injuries.

Hey NZ people - did any of you see this?


Public ID 2012p249591
Universal Time April 2 2012 at 8:22:24
NZ Standard Time Monday, April 2 2012 at 8:22:24 pm
Latitude, Longitude -42.18, 171.62
Intensity weak
Focal Depth 324km!!!!
Magnitude 3.6
Location 20 km west of Reefton
Agency WEL(GNS_Primary)


Beta

Odd location, very, very odd depth! Well I thought, but I could be wrong. It appears to me that this is in the "gap" that appears on the deep earthquake map. I know it's a "rapid" quake and not reviewed yet but it just looked like it was worth keeping an eye on? Maybe?

But then again, we really shouldn't worry anymore because according to Kelvin Berryman @ GNS the Apline fault is now less of a risk

update to post by PuterMan


Oaxaca now down to 6.0 Mw M (Unknown type) ??? WTH

earthquake.usgs.gov...

wtaq.com...

It's a big one.

.1 M

Second confirmed in the Great Clintonville Swarm.

reply to post by PuterMan


As long as there is shakin' and quakin',
sqiggly lines needin' explaining,
nerves needin' assurin'
and things that make you go hmmmm......
You my friend will always be relevant!

guess this shallow 4 mag in frisco a month ago,

wasn't anything spectacular or a foreshock?

For the first time in a long time I've felt excitable. Giddy. Why? Because I had just written a small description of my theory about Soddom and Gommorah in an email to an old and dear aquaintence. My version is so horrific. I shudder in mine own mind. People melted. Anyway.

Anyway. I was tingling as I went to check the world shake maps. Still thinking about big massive volcanoes exploding when they get flooded with water. I thought, oh I can feel her, Yellowstone is ready. I was already writing about the new swarm and blah blah, I'm an gloom and doom junkie. Shut up.

Oh by the way. There's a wee swarm starting up in west Yellowstone.

Also, I'm hearing sugar is worse than first thought.

Originally posted by Evltre
Hey NZ people - did any of you see this?


Public ID 2012p249591
Universal Time April 2 2012 at 8:22:24
NZ Standard Time Monday, April 2 2012 at 8:22:24 pm
Latitude, Longitude -42.18, 171.62
Intensity weak
Focal Depth 324km!!!!
Magnitude 3.6
Location 20 km west of Reefton
Agency WEL(GNS_Primary)


Beta

Odd location, very, very odd depth! Well I thought, but I could be wrong. It appears to me that this is in the "gap" that appears on the deep earthquake map. I know it's a "rapid" quake and not reviewed yet but it just looked like it was worth keeping an eye on? Maybe?

But then again, we really shouldn't worry anymore because according to Kelvin Berryman @ GNS the Apline fault is now less of a risk

I wouldn't pay too much attention to the Geonet Rapid at this stage, its OK to check to see what a quake size was if you felt it yourself, but I have noticed most of them don't end up appearing in the daily data as preliminary events (confirmed).
That one didn't show on April 2 data.

There have been some odd events happening the last 2-3 day though, swarm of quakes Mag 4 at Ngatoro Basin east of Auckland and several Mag 2 quakes just south of Dunedin. The Ngatoro Basin ones not so unusual, but they were very shallow for being under the sea 5, 6 and 8km deep.
The Dunedin ones more rare, you get maybe half a dozen a year down there, so thats 1/3 of the annual quota in a couple of days. ((see Last 7 days Map in my signature) (only relevant for 7 days though then you will have to go to the 30 days Map ))

reply to post by muzzy


thanks Muzzy

I had been a little concerned when it popped up out of the blue. There also seems to be quite a number around Tauranga, out past white island and yes I did see those Dunedin ones as well! your last 7 days of quakes is cool. Until the Beta thing I really didn't realise quite how active we were!

LOTS of people reporting it to USGS
earthquake.usgs.gov...

Magnitude
4.0
Date-Time
Tuesday, April 03, 2012 at 07:33:59 UTC
Tuesday, April 03, 2012 at 02:33:59 AM at epicenter
Time of Earthquake in other Time Zones
Location
34.689°N, 95.828°W
Depth
4.9 km (3.0 miles)
Region
OKLAHOMA
Distances
27 km (16 miles) SSW of McAlester, Oklahoma
78 km (48 miles) E of Ada, Oklahoma
176 km (109 miles) ESE of OKLAHOMA CITY, Oklahoma
230 km (142 miles) NNE of Dallas, Texas
Location Uncertainty
horizontal +/- 8.4 km (5.2 miles); depth +/- 3 km (1.9 miles)
Parameters
NST= 58, Nph= 74, Dmin=118 km, Rmss=1.09 sec, Gp= 43°,
M-type="Nuttli" surface wave magnitude (mbLg), Version=5
Source
Magnitude: USGS NEIC (WDCS-D)
Location: USGS NEIC (WDCS-D)
Event ID
usc0008uyu

earthquake.usgs.gov...

reply to post by berkeleygal


Did you see that one in mexico mag 6 on 3/4/2012 im surprised no one has posted about it

reply to post by berkeleygal


I am in Oklahoma City and I did not feel this quake. I was sound asleep. I did notice there were reports that people in my zip code and the surrounding zip codes did feel it though.

Earthquake activity here in Oklahoma sure has increased over the last year or so...wierd