[MSNoise] MSNoise Digest, Vol 31, Issue 1

Thu Oct 6 20:22:33 UTC 2016

Ahston,

No, don't worry about this, the values are converted to the right type 
when loaded from the config.

Thomas

On 06/10/2016 19:44, Flinders, Ashton wrote:
> p.s.  In the admin gui, under configuration, several of the values are set
> to numbers with a period "." after them. Is this necessary? E.g. are they
> there to force a decimal type in python 2.x opposed to an integer?
>
> On Thu, Oct 6, 2016 at 10:38 AM, Flinders, Ashton <aflinders at usgs.gov>
> wrote:
>
>> Thanks Esteban,
>>
>> I have looked through the documentation extensively, as well as the SRL
>> paper, and a bit of grepping on the source code (e.g. it took me a while to
>> figure out why in the world I couldnt remove instrument responses using a
>> RESP or PZ file, since it is listed on the documentation page, until I
>> grepped the source code and saw those were not implemented.)
>>
>> 1) Yes. It is more efficient to compute the cross-correlation functions or
>> Green’s functions using 30-min chunks. Although you can change this feature
>> if you will. Segments are re-build afterwards.
>>
>> This is only true if the daily segments are always preloaded into memory
>> (IO vs CC time). The SRL paper makes it sounds like this is the case, but I
>> want to make sure that this is always the case, even for processing many
>> stations/days or long segments. I also wasnt sure if these segmented CC
>> were used for any statistics (e.g. uncertainty in daily CC values).
>>
>> 2) You need to define the filters in order to compute the
>> cross-correlations and extract the coherent part of the ambient noise for a
>> given frequency range. MWCS is used to compute the moving window cross
>> spectral analysis after the cross-correlation procedure.
>>
>> Yes, I understand that (the way its been written) filter values should be
>> defined before the CC (which really should only be the whiteneing band or
>> preprocessing), however I dont understand why in the web gui the whiten and
>> MWCS filters are put within the same group. This make me predefine a MWCS
>> filter band, along with my whiten band, even though the MWCS doesnt happed
>> for another two processing steps. This leads to confusion, for example;
>>
>> What happens if I compute the CC's with a defined filter (as written, a
>> MWCS and whiten filter defined together) and then want to compute different
>> MWCS's later on when I actually get to the MWCS step. Can I just define a
>> new filter, with new mwcs_low mwcs_high values? Since the web gui forces me
>> to define a filter high low value (whiten, I assume) does it not use these?
>> Do I have to go back and recalculate the cross correlations everytime I
>> want to add an MWCS filter (which I wouldnt expect I have too)?
>>
>> Similarly, what happens if I want to delete a set of processed MWCS or
>> stacks? I cant just delete the folder, since their are still pointers in
>> the sql database. Just reprocessing doesnt seem to work either.
>>
>> thanks again
>>
>> -ashton
>>
>>
>>
>>
>> On Thu, Oct 6, 2016 at 10:17 AM, Esteban Chaves <echfisica at gmail.com>
>> wrote:
>>
>>> Hi Ashton,
>>>
>>> As an active user:
>>>
>>> I highly recommend you to check the documentation:
>>> http://msnoise.org/doc/workflow.html#module-msnoise.s03compute_cc <
>>> http://msnoise.org/doc/workflow.html#module-msnoise.s03compute_cc>
>>> I think the pre-processing and processing steps are well documented in
>>> the web site.
>>>
>>> 1) Yes. It is more efficient to compute the cross-correlation functions
>>> or Green’s functions using 30-min chunks. Although you can change this
>>> feature if you will. Segments are re-build afterwards.
>>>
>>> 2) You need to define the filters in order to compute the
>>> cross-correlations and extract the coherent part of the ambient noise for a
>>> given frequency range. MWCS is used to compute the moving window cross
>>> spectral analysis after the cross-correlation procedure.
>>>
>>> 3) dunno. May be Thomas can give you more info.
>>>
>>> -Esteban J. Chaves
>>>
>>>
>>>> On Oct 6, 2016, at 5:00 AM, msnoise-request at mailman-as.oma.be wrote:
>>>>
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>>>> Today's Topics:
>>>>
>>>>    1. new user (Flinders, Ashton)
>>>>
>>>>
>>>> ----------------------------------------------------------------------
>>>>
>>>> Message: 1
>>>> Date: Wed, 5 Oct 2016 13:10:53 -0700
>>>> From: "Flinders, Ashton" <aflinders at usgs.gov>
>>>> To: <msnoise at mailman-as.oma.be>
>>>> Subject: [MSNoise] new user
>>>> Message-ID:
>>>>        <CAPbWHEO7J_9dyMdKJ3SQkpGy9hG7N1M-COwgzGTpkVmy85ig5g at mail.
>>> gmail.com>
>>>> Content-Type: text/plain; charset="UTF-8"
>>>>
>>>> Hi all, long-time obspy user new MSnoise user.
>>>>
>>>> I just had a couple quick questions I was hoping to get clarification
>>> on;
>>>>>  From the SRL article;
>>>> "Once all waveforms are loaded in memory, the computation is done by
>>>> iteration of the station pairs, on the different components to compute
>>> and
>>>> the on the different filters for each defined window (30 minutes slices
>>> by
>>>> default)."
>>>>
>>>> 1) To be clear, the two time-series from a station-station pair are
>>> divided
>>>> into segments (30 minutes long, no overlap, by default), and the CC is
>>> done
>>>> on these segments? Are these segments then rebuilt into the daily CCF?
>>> Is
>>>> this segmentation purely for efficieny reasons, or is there something
>>> else
>>>> going on?
>>>>
>>>> 2) Why does msnoise compute_cc, not work if there is no MCWS filter
>>> defined?
>>>> 3) Is there an intelligent way to search the mailing list archive?
>>>>
>>>> Thanks for the help!
>>>>
>>>> -ashton
>>>>
>>>>
>>>> ------------------------------
>>>>
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>>>>
>>>> End of MSNoise Digest, Vol 31, Issue 1
>>>> **************************************
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>>
>>
>> --
>> Ashton F. Flinders, Ph.D
>> U.S. Geological Survey
>> 345 Middlefield Road
>> Menlo Park, CA 94025
>> (650) 329-5050
>>
>>
>