[aspect-devel] Fwd: Fw: Using seismic tomography as an input

Nuno Mendes Simão nuno.m.simao at durham.ac.uk
Wed Oct 25 01:50:15 PDT 2017


Hi Everyone

To start a thank you to Phil Heron to introduce me to the exciting world
of aspect and to you all for any help.

So...

I would like to use a Cartesian rectangular box 60*60*13 km (0.5 km
steps) oceanic Lithospheric/crustal P-velocity 3D model of a section of
an oceanic ridge to calculate

> 1st and mainly

its gravimetric anomaly, to be compared with ship borne recorded
gravimetric anomaly.

I understand that the bathymetry is needed to calculate the full
gravimetric anomaly, as a big portion of its signal is caused by the
interface between the water column and the seafloor. If the use of
bathymetry makes things difficult it would still be great to have a tool
that only calculates the geopotential anomaly caused by the tomographic
Cartesian box defined above. It would be straightforward for me later to
subtract the effect of the water column - seafloor from the gravimetric
observations to make the comparisons.

> and 2nd if possible
its Heat flux density

> As a note.

Normally when I do this in 2d cases I extract the contours that define
the velocity ranges that define discrete rheological layers using a
seismic velocity-density coefficient for each layer and use the method
of Talwani to calculate the geopotential anomalies.

Nuno




-------- Forwarded Message --------
Subject: 	Fw: [aspect-devel] Using seismic tomography as an input
Date: 	Fri, 20 Oct 2017 22:36:00 +0100
From: 	HERON, PHILIP J. <philip.j.heron at durham.ac.uk>
To: 	MENDES-SIMAO, NUNO MIGUEL <nuno.m.simao at durham.ac.uk>





Philip J. Heron
Junior Research Fellow
Dept. of Earth Sciences
Durham University
web: http://philheron.com

------------------------------------------------------------------------
*From:* Aspect-devel <aspect-devel-bounces at geodynamics.org> on behalf of
John Naliboff <jbnaliboff at ucdavis.edu>
*Sent:* 20 October 2017 17:53:23
*To:* aspect-devel at geodynamics.org
*Subject:* Re: [aspect-devel] Using seismic tomography as an input
 
Hi Phil,

There are currently postprocessors available for computing the geoid and
heat flux. Additional postprocessors for gravity are in the works.

Working examples - yes, please have your colleague send an email when
they have a concrete idea of what they would like to do. If they simply
want to map velocity variations into temperature anomalies that are used
as an initial condition, this should be fairly straightforward.

Cheers,
John

*************************************************
John Naliboff
Assistant Project Scientist, CIG
Earth & Planetary Sciences Dept., UC Davis

On 10/20/2017 01:37 AM, HERON, PHILIP J. wrote:
>
> Hi Paul and John,
>
>
> Thanks for the replies!
>
>
> "are you hoping to input seismic tomography models for the express
> purpose of obtaining a density and gravity model?"
>
>
> Yes, this is what he is looking to do. Heat flux would be a bonus, too.
>
>
> I've passed on the information and he is going to download Aspect this
> afternoon. I think this would be really neat if we can get a working
> example up and running from this. I'll keep you posted and I (or more
> than likely he) will drop back in with some questions.
>
>
> Thanks again,
>
>
> Phil
>
> ------------------------------------------------------------------------
> *From:* Aspect-devel <aspect-devel-bounces at geodynamics.org> on behalf
> of Bremner,Paul M <pbremner at ufl.edu>
> *Sent:* 19 October 2017 22:04:30
> *To:* aspect-devel at geodynamics.org
> *Subject:* Re: [aspect-devel] Using seismic tomography as an input
>  
>
> Hi Phil,
>
>
> I believe a 3D Cartesian model can be input into the ascii plug-in.
>
>
> I also just want to make sure I understand your purpose correctly, are
> you hoping to input seismic tomography models for the express purpose
> of obtaining a density and gravity model? Or are you wanting to simply
> use the tomography models to feed a density model to ASPECT?
>
>
> I believe that both the S40RTS and ascii plug-ins assign the
> temperature field in ASPECT, and not the density. For example, in
> S40RTS the velocity perturbation at a particular point is converted to
> density perturbation by multiplying a constant scale factor. That
> value is then multiplied by 1/alpha to get temperature perturbation,
> which is added to a background temperature for that point.
>
>
> Cheers,
> Paul
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