17 Feb
2018
17 Feb
'18
6:52 p.m.
Hi Illias,
This is really an exciting event!
From the video, it is clear that the volcano induced
lot of deformation at
the surface and some faulting. So, even if it is not active
anymore, you
may be able to monitor the re-compaction of the site in the near surface
and maybe extending deeper.
If you want to monitor what's happening down to the reservoir, it's more
tricky. You would need low frequencies (down to 0.1 Hz maybe) but these
frequencies mean long wavelength so poor spatial resolution. Given the
volume of mud erupted, the reservoir it's coming from might be quite small
(maybe few tens of meters thick), so it's not clear to me if one can see
changes at these depths using surface waves.
On the other hand, there might be some micro-seismicity down there that you
can record and locate with a surface network that would be helpful to
delineate the depth extent of the activity/reservoir.
Anyway, I would deploy the sensors as soon as possible. Maybe one station
really close to the volcano (<100m), two/three others at ~500m /1km and the
two last at 3-5 km from the vent. See my tentative of a design attached
(plus the .kmz file).
[image: Devil’s Woodyard mud volcano_seismicarray.jpg]
To give you an idea of what can be done with ambient noise and about the
seismicity on a (much bigger) mud volcano at Lusi in Indonesia, see the
papers attached.
Cheers,
Aurelien
Le sam. 17 févr. 2018 à 11:50, Thomas Lecocq <thomas.lecocq(a)seismology.be>
a écrit :
Hi Ilias,
Wooow... Impressive!
If I get it well, the current idea is that there is a reservoir at 3 to
6km deep and a "pipe" up to the surface ?
--
==========================
Postdoctoral associate
Department of Earth, Atmospheric and Planetary Sciences
Massachusetts Institute of Technology
54-526
Cambridge, MA 02139-4307
phone: 617-253-5051
e-mail: mordret(a)mit.edu
web: http://web.mit.edu/mordret/www
Questions in my mind are both of practical and
scientific perspective:
- Since we don't expect any conventional
seismic/volcanic activity,
will the network record anything of use?
Well you'll most probably have some tremor linked to the bubbling mud
going up, and maybe some events at deeper locations. Did you measure
anything with the permanent network ?
- I have in my hands 5 to 6 Guralp 5TDE
(accelerometers). Will they be
able to record noise down to the frequencies of
interest?
I don't have any experience of the 5TDE, could you send the estimated
instrument response? I bet they could be used down to 1Hz or even lower.
Did you do any measurement recently with those ? If yes, it'd be quite
easy to compute some coherency checks on the data.
- Related to the previous, what would be the
optimum aperture to
deploy the sensors (taking into account we need to extract
information
down to 3-6 Km)?
If you want to "monitor" the "reservoir" you'll need to open the
network
quite largely. Aurélien could answer this better than me, but I'm quite
sure you can open one triangle by 5 to 7 km and anther one with a
smaller aperture, both "centered" on the volcano.
In any case, I'd install them rapidly and check the data after 1 or 2
weeks max.
ps= don't forget to update to MSNoise 1.5.1 to have the latest bugfixes.
Best regards,
Tom
On 17/02/2018 17:33, Ilias Papadopoulos wrote:
Hello fellow MSNoise users,
I have in my hands a case of an erupted mud volcano. The event took
place between February 12th and February 13th and got attention very
quickly from media and people in Trinidad & Tobago. I don't know if
any of you have any experience working with MSNoise and mud volcanoes.
A high quality drone footage you can find here
<https://www.facebook.com/topshotaerialservices/videos/984076211740133/
,
story on the media here
<http://newsday.co.tt/2018/02/17/mud-volcano-goes-quiet/>.
I am thinking of setting up a project around it, but since there is
not much information as to what to expect, I seek advice from all of
you. According to geologists here, the whole thing has gone dormant on
the surface. There is no volcanic activity, hard rock or magma
movement underneath. Some studies propose a disturbance down to 3 or 6
Km of mud and gas intruding the younger harder formations.
Questions in my mind are both of practical and scientific perspective:
- Since we don't expect any conventional seismic/volcanic activity,
will the network record anything of use?
- I have in my hands 5 to 6 Guralp 5TDE (accelerometers). Will they be
able to record noise down to the frequencies of interest?
- Related to the previous, what would be the optimum aperture to
deploy the sensors (taking into account we need to extract information
down to 3-6 Km)?
Any ideas, suggestions or advice are appreciated.
Ilias
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