When an event occurs, there are four basic waves that are generated, the =
P, S, Love & Rayleigh waves.  The other waves are byproducts of =
reflection and refraction, but the four basic waves are generated at the =
event.    However, these four waves take time to properly form and be =
recognizable.  In addition, your receiver must have sufficient broad =
band capability to cover the frequencies of the various waves.  The P =
wave is normally the shorted frequency, followed by the S, Love and =
Rayleigh waves.  Your receiver is a higher frequency device and you may =
not be able to see smaller amplitude waves of lower frequency as clearly =
as the higher frequency receivers.

When the event recorded from the IDA station was expanded to 10 seconds, =
there was one wave that began about 11:12.294, and ended about  =
11:12.672 that is definitely a lower frequency and may be an S wave.  It =
would take more work to define that wave as an S wave but there is a =
possibility for that one.  It appears that the primary problem you are =
dealing with is the closeness of the station to the event and lack of =
time for the various waves to be individually distinguishable.

There may be other answers that are more correct, but that is what it =
appears after expanding the file and looking at it.

Bob Hancock



On Dec 15, 2012, at 9:32 AM, Tiago A.  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

tiagoagre@.........> =
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.



=