I was watching those on the heliplot display when I saw the posting on the =
most recent M6.9 -
=A0
Steve Jones
AlabamaQuake

--- On Fri, 4/20/12, Dave Nelson  wrote:


From: Dave Nelson 
Subject: Weird recording results
To: psnlist@..............
Date: Friday, April 20, 2012, 8:01 PM


hi gang

here's a weird one for you to ponder ....
there's just been 3 events offshore NW=A0 Sumatera=A0 (aftershocks of the 8=
..6 and 8.2)

6.1=A0=A0=A02012/04/20 23:14:33=A0 =A0 2.218=A0 =A0 93.395=A0 34.3=A0=A0=A0=
OFF THE WEST COAST OF NORTHERN SUMATRA
5.5=A0=A0=A02012/04/20 22:29:00=A0 =A0 3.280=A0 =A0 93.858=A0 28.3=A0=A0=A0=
OFF THE WEST COAST OF NORTHERN SUMATRA
5.6=A0=A0=A02012/04/20 22:19:46=A0 =A0 3.261=A0 =A0 93.850=A0 16.9=A0=A0=A0=
OFF THE WEST COAST OF NORTHERN SUMATRA

the 5.6=A0 followed by the 5.5 and then the 6.1, as you can see they were a=
ll relatively shallow and similar
location.

The P and S of the 5.6 was visible with a bit of imagination, nothing of th=
e 5.5 and nothing of the 6.1
The surface waves of the 5.6 obvious, those of the 5.5 significantly larger=
 than the 5.6 and nothing from
the 6.1

Even the ASL station in northern Queensland, Australia backs this up where =
its vertical sensor shows the
surface waves of the 6.1 being similar amplitude to the 5.5
http://earthquake.usgs.gov/monitoring/operations/data/Seismic_Data/telemetr=
y_data/CTAO_24hr.html

My sensor is N-S, the CTAO sensor is as said Z.=A0=A0=A0the epic's are roug=
hly NW of me and WNW of CTAO

just an interesting observation. It really must have something to do with t=
he orientation of the fault slip
and the direction of propagation of the waves. Interestingly on any of the =
ASL=A0 WWSSN, the 6.1 surface waves were only a little bigger than those of=
 the 5.5

cheers
Dave

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Public Seismic Network Mailing List (PSNLIST)

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I was watching those on the heliplot dis=
play when I saw the posting on the most recent M6.9 -
 
Steve Jones
AlabamaQuake

--- On Fri, 4/20/12, Dave Nelson <dave.ne=
lson@...............> wrote:


From: Dave Nelson <dave.nelson@................
>
Subject: Weird recording results
To: psnlist@..............
D=
ate: Friday, April 20, 2012, 8:01 PM


hi gang

here's a weird one for you to ponder =
.....
there's just been 3 events offshore NW  Sumatera  (afters=
hocks of the 8.6 and 8.2)

6.1   2012/04/20 23:14:33&n=
bsp;   2.218    93.395  34.3   OFF THE W=
EST COAST OF NORTHERN SUMATRA
5.5   2012/04/20 22:29:00&n=
bsp;   3.280    93.858  28.3   OFF THE W=
EST COAST OF NORTHERN SUMATRA
5.6   2012/04/20 22:19:46&n=
bsp;   3.261    93.850  16.9   OFF THE W=
EST COAST OF NORTHERN SUMATRA

the 5.6  followed by the 5.5 and =
then the 6.1, as you can see they were all relatively shallow and similarlocation.

The P and S of the 5.6 was visible with a bit of imagina=
tion, nothing of the 5.5 and nothing of the 6.1
The surface waves of the=
 5.6 obvious, those of the 5.5 significantly larger than the 5.6 and
 nothing from
the 6.1

Even the ASL station in northern Queensland=
, Australia backs this up where its vertical sensor shows the
surface wa=
ves of the 6.1 being similar amplitude to the 5.5
http://earthquake.usgs.gov/monitoring/operation=
s/data/Seismic_Data/telemetry_data/CTAO_24hr.html

My sensor is N=
-S, the CTAO sensor is as said Z.   the epic's are roughly N=
W of me and WNW of CTAO

just an interesting observation. It really m=
ust have something to do with the orientation of the fault slip
and the =
direction of propagation of the waves. Interestingly on any of the ASL =
; WWSSN, the 6.1 surface waves were only a little bigger than those of the =
5.5

cheers
Dave

__________________________________________=
________________

Public Seismic Network Mailing List
 (PSNLIST)

To leave this list email PSNLIST-REQUEST@.............. with t=
he body of the message (first line only): unsubscribe
See http://www.seismicnet=
..com/maillist.html for more information.