# Finding Big Bertha with a hot wire

Sunday will be the 131st birthday of General Andrew McNaughton, a Canadian electrical engineer who served in the Canadian Expeditionary Force in the First World War. He was eventually appointed commander of the Canadian Corps Heavy Artillery and went on to serve in the Second World War as well.

So what is a professional soldier doing on a blog about geoscience? Well, McNaughton was part of the revolution of applied acoustics and geophysics that emerged right before and after the First World War.

Along with eminent British physicist Lawrence Bragg, engineer William Sansome Tucker, and physicist Charles Galton Darwin (the other Charles Darwin's grandson), among others, McNaughton applied physics to the big problem of finding the big noisy things that were trying to blow everyone up. They were involved in an arms race of their own — German surveyor Ludger Mintrop was trying to achieve the same goal from the other side of the trenches.

After gaining experience as a gunner, McNaughton became one of a handful of scientists and engineers involved in counter-battery operations. Using novel ranging techniques, these scientists gave the allied forces a substantial advantage over the enemy. Counter-battery fire became an weapon at pivotal battles like Vimy Ridge, and certainly helped expedite the end of the war.

If all this sounds like a marginal way to win a battle, stop think for a second about these artillery. The German howitzer, known as 'Big Bertha' (left), could toss an 820 kg (1800 lb) shell about 12.5 km (7.8 miles). In other words, it was incredibly annoying.

### Combining technologies

Localization accuracy on the order of 5–10 m on the large majority of gun positions was eventually achieved by the coordinated use of several technologies, including espionage, cartography, aerial reconnaissance photography, and the new counter-measures of flash spotting and sound ranging.

Flash spotting was more or less just what it sounds like: teams of spotters recording the azimuth of artillery flashes, then triangulating artillery positions from multiple observations. The only real trick was in reporting the timing of flashes to help establish that the flashes came from the same gun.

Sound ranging, on the other hand, is a tad more complicated. It seems that Lawrence Bragg was the first to realize that the low frequency sound of artillery fire — which he said lifted him off the privy seat in the outhouse at his lodgings — might be a useful signal. However, microphones were not up to the task of detecting such low frequencies. Furthermore, the signal was masked by the (audible) sonic boom of the shell, as well as the shockwaves of passing shells.

Elsewhere in Belgium, William Tucker had another revelation. Lying inside a shack with holes in its walls, he realized that the 20 Hz pressure wave from the gun created tiny puffs of air through the holes. So he looked for a way to detect this pulse, and came up with a heated platinum wire in a rum jar. The filament's resistance dropped when cooled by the wavefront's arrival through an aperture. The wire was unaffected by the high-frequency shell wave. Later, moving-coil 'microphones' (geophones, essentially) were also used, as well as calibration for wind and temperature. The receivers were coupled with a 5-channel string galvanometer, invented by French engineers, to record traces onto 35-mm film bearing timing marks:

McNaughton continued to develop these technologies through the war, and by the end was successfully locating the large majority of enemy artillery locations, and was even able to specify the calibre of the guns and their probable intended targets. Erster Generalquartiermeister Erich Ludendorff commented at one point in the war:

### An acoustic arsenal

The hot-wire artillery detector was not Tucker's only acoustic innovation. He also pioneered the use of acoustic mirrors for aircraft detection. Several of these were built around the UK's east coast, starting around 1915 — the three shown here are at Denge in Kent. They were rendered obselete by the invention of radar around the beginning of World War Two.

Acoustic and seismic devices are still used today in military and security applications, though they are rarely mentioned in applied geophysics textbooks. If you know about any interesting contemporary uses, tell us about it in the comments.

According to Crown Copyright terms, the image of McNaughton is out of copyright. The acoustic mirror image is by Paul Russon, licensed CC-BY-SA. The uncredited/unlicensed galvanometer trace is from the excellent Stop, hey, what's that sound article on the geographical imaginations blog; I assume it is out of copyright. The howitzer image is out of copyright.

This post on Target acquisition and counter battery is very informative and has lots of technical details, though most of it pertains to later technology. The Boom! Sounding out the enemy article on ScienceNews for Students is also very nice, with lots of images.

### Matt Hall

Matt is a geoscientist in Nova Scotia, Canada. Founder of Agile Scientific, co-founder of The HUB South Shore. Matt is into geology, geophysics, and machine learning.

# Unsolved problems in applied geoscience

I like unsolved problems. I first wrote about them way back in late 2010 — Unsolved problems was the eleventh post on this blog. I touched on the theme again in 2013, before and after the first 'unsession' at the GeoConvention, which itself was dedicated to finding the most pressing questions in exploration geoscience. As we turn towards the unsession at AAPG in Salt Lake City in May, I find myself thinking again about unsolved problems. Specifically, what are they? How can we find them? And what can we do to make them easier to solve?

It turns out lots of people have asked these questions before.

I've compiled a list of various attempts by geoscientists to list he big questions in the field. The only one I was previous aware of was Milo Backus's challenges in applied seismic geophysics, laid out in his president's column in GEOPHYSICS in 1980 and highlighted later by Larry Lines as part of the SEG's 75th anniversary. Here are some notable attempts:

• John William Dawson, 1883 — Nova Scotia's most famous geologist listed unsolved problems in geology in his presidential address to the American Association for the Advancement of Science. They included the Cambrian Explosion, and the origin of the Antarctic icecap.
• Leason Heberling Adams, 1947 — One of the first experimental rock physicists, Adams made the first list I can find in geophysics, which was less than 30 years old at the time. He included the origin of the geomagnetic field, and the temperature of the earth's interior.
• Milo Backus, 1980 — The list included direct hydrocarbon detection, seismic imaging, attenuation, and anisotropy.
• Mary Lou Zoback, 2000 — As her presidential address to the GSA, Zoback kept things quite high-level, asking questions about finding signal indynamic systems, defining mass flux and energy balance, identifying feedback loops, and communicating uncertainty and risk. This last one pops up in almost every list since.
• Calgary's geoscience community, 2013 — The 2013 unsession unearthed a list of questions from about 50 geoscientists. They included: open data, improving seismic resolution, dealing with error and uncertainty, and global water management.
• Daniel Garcia-Castellanos, 2014 — The Retos Terrícolas blog listed 49 problems in 7 categories, ranging from the early solar system to the earth's interior, plate tectonics, oceans, and climate. The list is still maintained by Daniel and pops up occasionally on other blogs and on Wikipedia.

The list continues — you can see them all in this presentation I made for a talk (online) at the Bureau of Economic Geology last week (thank you to Sergey Fomel for hosting me!). During the talk, I took the opportunity to ask those present what their unsolved problems are, especially the ones in their own fields. Here are a few of what we got (the rest are in the preso):

What are your unsolved problems in applied geoscience? Share them in the comments!

If you have about 50 minutes to spare, you can watch the talk here, courtesy of BEG's streaming service.

### Matt Hall

Matt is a geoscientist in Nova Scotia, Canada. Founder of Agile Scientific, co-founder of The HUB South Shore. Matt is into geology, geophysics, and machine learning.

# Easier, better, faster, stronger

Yesterday I pushed a new release of bruges to Python's main package repository, PyPi.  Version 0.3.3 might not sound like an especially auspicious version perhaps, but I'm excited about the new things we've added recently. It has come a long way since we announced it back in 2015, so if you haven't checked it out lately, now's a good time to take another look.

### What is bruges again?

Bruges is a...

In other words, nothing fancy — just equations. It is free, open source software. It's aimed at geophysicists who use Python.

How do you install it? The short answer is pip:

    pip install bruges

### So what's new?

Here are the highlights of what's been improved and added in the last few months:

• The reflectivity equations in reflection module now work on arrays for the Vp, Vs, and rho values, as well as the theta values. This is about 10 times faster than running a loop over elements; the Zoeppritz solution is 100× faster.
• The various Zoeppritz solutions and the Aki–Richards approximations now return the complex reflectivity and therefore show post-critical amplitudes correctly.
• A new reflection coefficient series function, reflection.reflectivity(), makes it easier to compute offset reflectivities from logs.
• Several new linear and non-linear filters are in bruges.filters, including median (good for seismic horizons), mode (good for waveform classification), symmetric nearest-neighbours or snn, and kuwahara.
• The wavelets ricker(), sweep() (aka Klauder) and ormsby() wavelet now all work for a sequence of frequencies, returning a wavelet bank. Also added a sinc() wavelet, with a taper option to attenuate the sidelobes.
• Added inverse_gardner, and other density and velocity transforms, to petrophysics.
• Added transform.v_rms() (RMS velocity), transform.v_avg() (average velocity) and transform.v_bac() (naïve Backus average). These all operate in a 'cumulative' average-down-to sense.
• Added a coordinate transformation to translate between arbitrarily oriented (x,y) and (inline, line) coordinates.

Want to try using it right now, with no installation? Give it a spin in My Binder! See how easy it is to compute elastic moduli, or offset reflection coefficients, or convert a log to time.

Want to support the development of open source geophysics software? Here's how:

• Use it! This is the main thing we care about.
• Report problems on the project's Issue page.
• Fork the project and make your own changes, then share them back.
• Pay us for the development of functionality you need.

### Matt Hall

Matt is a geoscientist in Nova Scotia, Canada. Founder of Agile Scientific, co-founder of The HUB South Shore. Matt is into geology, geophysics, and machine learning.

# This year's social coding events

If you've always wondered what goes on at our hackathons, make 2018 the year you find out. There'll be plenty of opportunities. We'll be popping up in Salt Lake City, right before the AAPG annual meeting, then again in Copenhagen, before EAGE. We're also running events at the AAPG and EAGE meetings. Later, in the autumn, we'll be making some things happen around SEG too.

If you just want to go sign up right now, head to the Events page. If you want more deets first, read on.

### Salt Lake City in May: machine learning and stratigraphy

This will be one of our 'traditional' hackathons. We're looking for 7 or 8 teams of four to come and dream up, then hack on, new ideas in geostatistics and machine learning, especially around the theme of stratigraphy. Not a coder? No worries! Come along to the bootcamp on Friday 18 May and acquire some new skills. Or just show up and be a brainstormer, tester, designer, or presenter.

### Algorithmic puzzles and stuff

These are spectacular: randomly generated agate-like jigsaw puzzles. Every one is different! Even the shapes of the wooden pieces are generated with maths. They cost about USD 95, and come from Boston-based Nervous System. The same company has lots of other rock- and fossil-inspired stuff, like ammonity jewellery (from about USD 50) and some very cool coasters that look a bit like radiolarians (USD 48 for 4).

### There's always books

You can't go wrong with books. These all just came out, and just might appeal to a geoscientist. And if these all sound a bit too much like reading for work, try the Atlas of Beer instead. Click on a book to open its page at Amazon.com.

### The posts of Christmas past

If by any chance there aren't enough ideas here, or you are buying for a very large number of geoscientists, you'll have to dredge through the historical listicles of yesteryear — 20112012201320142015, or 2016. You'll find everything there, from stocking stuffers to Triceratops skulls.

The images in this post are all someone else's copyright and are used here under fair use guidelines. I'm hoping the owners are cool with people helping them sell stuff!

1 Comment

### Matt Hall

Matt is a geoscientist in Nova Scotia, Canada. Founder of Agile Scientific, co-founder of The HUB South Shore. Matt is into geology, geophysics, and machine learning.

# Not getting hacked

The end of the year is a great time to look around at your life and sort stuff out. One of the things you almost certainly need to sort out is your online security. Because if you haven't been hacked already (you probably have), you're just about to be.

Just look at some recent stories from the world of data security:

There are plenty of others; Wired has been keeping track of them — read more here. Or check out Wikipedia's list.

Despite all this, I see hardly anyone using a password manager, and anecdotally I hear that hardly anyone uses two-factor authentication either. This tells me that at least 80% of smart people, inlcuding lots of my friends and relatives, are in daily peril. Oh no!

After reading this post, I hope you do two things:

• Start using a password manager. If you only do one thing, do this.
• Turn on two-factor authentication for your most vulnerable accounts.

### Start using a password manager

Please, right now, download and install LastPass on every device and in every browser you use. It's awesome:

• It stores all your passwords! This way, they can all be different, and each one can be highly secure.
• It generates secure, random passwords for new accounts you create.
• It scores you on the security level of your passwords, and lets you easily change insecure ones.
• The free version is awesome, and the premium version is only \$2/month.

There are other password managers, of course, but I've used this one for years and it's excellent. Once you're set up, you can start changing passwords that are insecure, or re-used on multiple sites... or which are at Uber, Yahoo, or Equifax.

One surprise from using LastPass is being able to count the number of accounts I have created around the web over the years. I have 473 accounts stored in LastPass! That's 473 places to get hacked... how many places are you exposed?

### Two-factor authentication

Sure, it's belt and braces — but you don't want your security trousers to fall down, right?

Er, anyway, the point is that even with a secure password, your password can still be stolen and your account compromised. But it's much, much harder if you use two-factor authentication, aka 2FA. This requires you to enter a code — from a hardware key or an app, or received via SMS — as well as your password. If you use an app, it introduces still another layer of security, because your phone should be locked.

I use Google's Authenticator app, and I like it. There's a little bit of hassle the first time you set it up, but after that it's plain sailing. I have 2FA turned on for all my 'high risk' accounts: Google, Twitter, Facebook, Apple, AWS, my credit card processor, my accounting software, my bank, my domain name provider, GitHub, and of course LastPass. Indeed, LastPass even lets me specify that logins must originate in Canada.

### What else can you do?

There are some other easy things you can do to make yourself less hackable:

• Install updates on your phones, tablets, and other computers. Keep browsers and operating systems up to date.
• Be on high alert for phishing attempts. Don't follow links to sites like your bank or social media sites — type them into your browser if possible. Be very suspicious of anyone contacting you, especially banks.
• Don't use USB sticks. The cloud is much safer — I use Dropbox myself, it's awesome.

For more tips, check out this excellent article from Motherboard on not getting hacked.