
Geophysicists are ramping up their efforts to monitor major undersea faults - sohkamyung
https://www.nature.com/news/the-fight-to-save-thousands-of-lives-with-sea-floor-sensors-1.22178
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comstock
I found this really interesting. I was curious about the Japanese realtime
sea-floor sensors they mentioned so I went hunting.

The data appears to be available here:

[http://www.jamstec.go.jp/scdc/top_e.html](http://www.jamstec.go.jp/scdc/top_e.html)

After registration [1] you can download data in some funky binary format.
Looks like there's a 10min delay on data. It looks like an interesting
dataset, and I hope to play with it a bit.

[1] includes such joys as password being set to username, and the seeming
inability to change your password citing "invalid chars: 1" error.

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angrygoat
I used to work at an exploration geophysics firm, these data formats less
scary than you'd often encounter in that world. There are a number of
interchange formats in geophysics, notably SEG-Y, which date back a long way –
most vendors then have their custom formats that they ingest that interchange
format into:

[https://en.wikipedia.org/wiki/SEG_Y](https://en.wikipedia.org/wiki/SEG_Y)

Fundamentally you've usually got one to three dimensional data, metadata for
the entire file, and then metadata for (potentially) each column along some
axis of the file. It's interesting that CDF, etc have had zero traction: I
guess it's just that each field has its little data format subculture and
there's not much incentive for collaboration?

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shiftpgdn
I currently work at an exploration geophysics firm and was just talking to my
boss about this yesterday. His comment was that data acquisition had an arms
race to the bottom in the late 80s and has become complete commodity object.
This has results in data from the 80s through today being no different as
they're still using the (mostly) same tools and techniques.

There is no incentive to better your seismic surveying since stuff from the
80s is "good enough" for all the processing shops.

~~~
angrygoat
Yep, that sounds about right, at least on the data formats. A survey now is
gathering orders of magnitude more data than it would have in the 80s
(especially 3d/4d surveys), but I guess the formats didn't really need to
change.

I don't miss writing code to guess whether a file has traces encoded in IBM
floating point or IEEE; or handling SEG-Y headers which ought to be EBCDIC but
are sometimes ASCII :-)

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pmontra
A sci-fi apocalyptic story starting with the underwater monitoring of the Juan
De Fuca fault: Peter Watt's Starfish.

[http://www.goodreads.com/book/show/66479.Starfish](http://www.goodreads.com/book/show/66479.Starfish)

Free in various formats on the author's web site

[http://www.rifters.com/real/STARFISH.htm](http://www.rifters.com/real/STARFISH.htm)

~~~
hellbanner
I highly recommend his Blindsight & Echopraxia duo, too. Also with dense
appendixes at the end.

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lambdadmitry
I wonder if US military takes part in the project: ultra-precise pressure
gauges may be exactly what's needed to detect subs

~~~
jofer
Actually, you wouldn't get a signal from a sub going overhead with these.

They're focused on recording relatively low-frequency response, so they don't
pick up sound (hydrophones do a great job of that, and they're dirt cheap).
Subs are neutrally buoyant, so there's no pressure anomaly. There will be a
tiny one from the bow wake, but that's the sort of thing you're trying not to
detect.

Part of the entire point of these is to sum out things like waves (and
possible minor blips like the bow wake from a nearby sub). You're summing over
time to get a very precise average height of the water above the sensor.
You're deliberately designing the sampling system to not be sensitive to small
temporal blips and filtering the data to remove any that show up.

Basically, if you want to detect subs, there are far cheaper and easier ways
to do it. These tools are designed to do something very different.

~~~
lambdadmitry
Yeah, I was thinking about bow wake as it's probably very hard to hide that
(as opposed to silencing the sound).

Thanks for your explanation, it makes ton of sense!

~~~
bluGill
you may not need to hide it so much as disguise it. There are lots of things
swimming in the oceans, some of them big. None as big as a sub, but a well
designed sub can potentially present that wake signature. (maybe not all the
time, but a sub can choose to go at a slow hiding pace or a fast but visible
pace)

