DAVE -=20

The link allowed me to download the files.  Once downloaded, they opened =
OK in both WinQuake and SAC.=20

Bob Hancock





























On Dec 15, 2012, at 2:16 PM, Dave Nelson  =
wrote:

>=20
> Dunno about anyone else but I cannot open your .sac files
> WinQuake refuses to look at it  ??
> can you not save them as standard Winquake files ?
>=20
> Dave
>=20
>=20
> At 03:32 PM 15/12/2012 -0100, you wrote:
>> Hi.
>>=20
>> Sorry for the late reply.
>>=20
>> The sensor is a L4 1Hz, i do have a noisy system due to several =
factors (some already discussed here in PSN Listing Mail).
>>=20
>> Here is the SAC file of the event:
>> http://dl.dropbox.com/u/15802004/12_10_2012.sac
>>=20
>> This the SAC file of the IDA station located +-10km of the event =
(much better recording than mine).
>> http://dl.dropbox.com/u/15802004/cmla_12_10_2012.sac
>>=20
>> I do not know if this is a "natural" event, while i do receive some =
"blasts" every month, at 4am i dont believe to be a blast.This event is =
located near a dormat volcano, that 10 years back had high seismic =
crisis. Some believe that the geothermal exploration on that system =
turned the system a bit unstable ( coincidence when they started the =
exploration back in the 80s, the area had a big seismic crisis). This =
event was classified with Ml1.8, 5km depth.
>>=20
>> So the hypothesis are:
>> -Only S wave was recorded, P wave is missed between the noise.
>> -Only P wave is clearly recorded.
>> -Due to short distance to the epicenter, P and S waves are mixed =
together.
>>=20
>> But except this event and 1/2 more, i can always understand if a P is =
recorded or not. Comparing my SAC file with the CMLA IDA station, what =
do you think?
>>=20
>> Best Regards,
>> Tiago.
>>=20
>>=20
>>=20
>>=20
>>=20
>> 2012/12/13 Bob Hancock 
>> One other thought, the peak amplitudes of the P & S waves are 90 =
degrees out of phase.  Also the classification of the focal mechanism of =
the event could have contributed to one wave being much more visible =
than the other wave. =20
>>=20
>> The amplitude of body waves such as the P & S waves, are dependent =
upon the focal mechanism of the event.
>>=20
>> Another factor is the sensitivity range or band width of your =
receiver.  If it is either a high frequency receiver or of minimal band =
width, you could see the P wave and the S wave would not be visible, =
whereas with a broader band receiver both waves would be visible. =20
>>=20
>> Your email does not define the scale at the bottom of the chart, =
minutes or seconds, but in either case no surface waves are visible.  =
Again this could be related to the frequency range of your receiver.
>> Bob Hancock
>>=20
>> On Dec 12, 2012, at 4:20 PM, Tiago A.  wrote:
>>=20
>>> Hi.
>>>=20
>>> Some months back i recorded a Ml1.8 event (epicenter at 22km), the P =
wave is perfectly noticed, but the S wave is somewhat lost.=20
>>>=20
>>> This is a picture of the earthquake (no filter applied)..i can get =
the sac file if anyone is interested. A IDA station located more near =
from the epicenter also have this "issue" in this earthquake, clear P =
wave, S wave bit lost.
>>> http://imageshack.us/a/img252/2303/12102012.png
>>>=20
>>> I=B4ve this video from another event (Ml2.9) near that area, also =
doesnt have a clear S wave.
>>> https://www.youtube.com/watch?v=3Dj0P2y2ahDNg
>>>=20
>>> In the Ml1.8 event the lack of a clear S Wave is more evident, what =
happened to the S wave? This events occured near a volcanic region, but =
i=B4ve recorded earthquakes from other volcanic regions, and i have =
always a clear P, S wave.
>>>=20
>>> I apreciate any thought on this.
>>>=20
>>> Regards,
>>> Tiago.

dave.nelson@...............> wrote:



Dunno about anyone else but I cannot open your .sac files

WinQuake refuses to look at it  ??

can you not save them as standard Winquake files ?


Dave




At 03:32 PM 15/12/2012 -0100, you wrote:

Hi.


Sorry for the late reply.


The sensor is a L4 1Hz, i do have a noisy system due to several factors
(some already discussed here in PSN Listing Mail).


Here is the SAC file of the event:

http://dl.dropbox=
..com/u/15802004/12_10_2012.sac


This the SAC file of the IDA station located +-10km of the event (much
better recording than mine).

http://dl.dr=
opbox.com/u/15802004/cmla_12_10_2012.sac


I do not know if this is a "natural" event, while i do receive
some "blasts" every month, at 4am i dont believe to be a
blast.This event is located near a dormat volcano, that 10 years back =
had
high seismic crisis. Some believe that the geothermal exploration on =
that
system turned the system a bit unstable ( coincidence when they started
the exploration back in the 80s, the area had a big seismic crisis). =
This
event was classified with Ml1.8, 5km depth.


So the hypothesis are:

-Only S wave was recorded, P wave is missed between the noise.

-Only P wave is clearly recorded.

-Due to short distance to the epicenter, P and S waves are mixed
together.


But except this event and 1/2 more, i can always understand if a P is
recorded or not. Comparing my SAC file with the CMLA IDA station, what =
do
you think?


Best Regards,

Tiago.








2012/12/13 Bob Hancock
<raptor@.......>

One other thought, the peak amplitudes of the P & S waves are 90
degrees out of phase.  Also the classification of the focal
mechanism of the event could have contributed to one wave being much =
more
visible than the other wave.  



The amplitude of body waves such as the P & S waves, are
dependent upon the focal mechanism of the event.



Another factor is the sensitivity range or band width of your
receiver.  If it is either a high frequency receiver or of minimal
band width, you could see the P wave and the S wave would not be =
visible,
whereas with a broader band receiver both waves would be visible. 




Your email does not define the scale at the bottom of the =
chart,
minutes or seconds, but in either case no surface waves are
visible.  Again this could be related to the frequency range of =
your
receiver. 
Bob Hancock



On Dec 12, 2012, at 4:20 PM, Tiago A.
<tiagoagre@.........>
wrote:



Hi.



Some months back i recorded a Ml1.8 event (epicenter at 22km), =
the P
wave is perfectly noticed, but the S wave is somewhat lost. 



This is a picture of the earthquake (no filter applied)..i can =
get
the sac file if anyone is interested. A IDA station located more near
from the epicenter also have this "issue" in this earthquake,
clear P wave, S wave bit lost.
http://imageshack=
..us/a/img252/2303/12102012.png



I=B4ve this video from another event (Ml2.9) near that area, =
also
doesnt have a clear S wave.
https://www.youtube=
..com/watch?v=3Dj0P2y2ahDNg



In the Ml1.8 event the lack of a clear S Wave is more evident, =
what
happened to the S wave? This events occured near a volcanic region, but
i=B4ve recorded earthquakes from other volcanic regions, and i have =
always
a clear P, S wave.



I apreciate any thought on this.



Regards,
Tiago.


=