Bullet in the brain

On 1 August this year, a story appeared in the Guardian concerning a man who turned up at King’s College hospital, south London, complaining that he’d been shot in the head.

To the shock and amazement of the triage nurses, this man explained that he had just been shot in the head and had caught a bus to the hospital. He was rushed into theatre where the surgeons who operated upon him duly removed a bullet from his brain.

This incident actually happened in 2003, but was in the news this month due to the case having at long last come to the courts.

Coincidences are always intriguing. I’m not one to claim any great significance attaches to them. Given the sheer number of things that happen every day, the strangest thing would be if there were never any coincidences. The coincidence here, for me, was that the very day this story appeared, I had just finished reading a classic detective novel in which the plot spring is that the murder victim continues to live for some minutes after being shot, long enough to get himself away from the scene of the shooting and attempt to rig up revenge against the man who shot him. I won’t mention the name of the novel so as not to spoil it for anyone who might be reading it in the future.

The author, who was writing c. 1940, includes a note at the end of the book to state that it is medically possible to survive for a while with a bullet in the brain, and to cite a few pieces of medical case history to illustrate it. What was strange for me was to find by chance a modern example in the newspaper the very same day.

Ground motion complexity

Here’s a puzzle for the ground motion modelling community. We all know that the average strong ground motion model computes motion as a function of magnitude, distance, fault style (usually) and site conditions (usually). Imponderables that also affect it include rupture direction, slip distribution, and path effects (refraction, reflection and interference as waves are transmitted through a heterogeneous medium).

But who was the first to identify that path heterogeneity due, for instance, to faulting, would add complexity to the transmission of seismic waves? Or if you can’t supply a name, how about a decade?

1980s? 1960s? Astonishingly, the answer is (arguably) the 1760s, and the individual in question is that remarkable pioneer John Michell, who also has to his credit being the first person to posit the existence of black holes.

Here he is:

… there is another very remarkable appearance in the structure of the earth, though a very common one; and this is what is usually called by miners the trapping down of the strata; that is, the whole set of strata on one side a cleft are sunk below the level of the corresponding strata on the other side. If, in some cases, this difference in the level of the strata on the different sides of the cleft should be very considerable, it may have a great effect in producing some of the singularities of particular earthquakes.

While this could be more explicit, Michell knew that earthquake shaking consisted in the transmission of elastic waves, and I don’t think it is too unreasonable to interpret this statement (which is not amplified by the author) as implying complexity in transmission.

Natanael Berg

I mentioned a few days ago the first symphony of Natanael Berg (the second symphony is rather a more convincing piece, by the way). I thought I was reasonably au fait with Scandinavian composers of the late Romantic period, but this name was quite new to me. He seems to have been something of an unusual figure. Apart from his musical life, he was an officer in the Swedish Army – as a military vetinarian, with particular reponsibility for the well-being of the horses essential for royal pageantry. He would even turn up to conduct concerts dressed in military uniform.

There is always some minor amusement to be had from composers who share the last name of more famous composers. Thus, one can cause some raised eyebrows by referring to “Berg’s Second Symphony”, since the first name that will come to mind will be that of Alban Berg, not exactly a symphonist. Mention of Schuman’s Sixth Symphony can also be puzzling, though when one writes it down, it is obvious from the single “n” that it is William Schuman and not Robert Schumann that is intended. And what about Tchaikovsky’s Cello Concerto? Oh, sorry, I meant Boris Tchaikovsky, of course!

Another great Alaskan earthquake ...

It is truly astonishing some of the things you can find on the internet. Take this, for example. I’m deliberately not providing a link to the original. Read it, try and work out the meaning of it.

At 5:36 p.m. Alaska Standard Time (3:36 a.m. March 28, 1964 UTC), a fault between the Pacific and North American plates ruptured near Anasenko Fjord in Tsarevitch Sound. The epicenter of the earthquake was 61°03′N 147°29′W / 61.05°N 147.48°W / 61.05; -147.48, 12.4 mi (20 km) north of Tsarevitch Sound, 78 miles (125 km) east of Aleksandrgrad and 40 miles (64 km) west of Valdez. The focus occurred at a depth of approximately 15.5 mi (25 km). Ocean floor shifts created large tsunamis (up to 220 feet (67 m) in height), which resulted in many of the deaths and much of the property damage.[5] Large rockslides were also caused, resulting in great property damage. Vertical displacement of up to 38 feet (11.5 m) occurred, affecting an area of 100,000 miles² (250,000 km²) within Alaska.

Studies of ground motion have led to a peak ground acceleration estimate of 0.14 – 0.18 g.[6]

…  Due to the proximity of the epicenter to Alaska’s then-second largest city and then-largest metropolitan region, the damage was enormously catastrophic. Estimates of casualties have typically ranged between 70,000 to 80,000, with the official death toll published by the Alaskan government being 77,455. Along with the deaths in Alaska itself, the tsunamis caused the deaths of about 30 people in Oregon and California …

The bulk of the damage occurred in Aleksandrgrad proper and its surrounding region, where about 55,000 people are estimated to have been killed – making the earthquake the greatest single loss of life in Alaskan history. Poorly-built public housing collapsed city-wide, and many such buildings collapsed into other buildings as they fell. Due to the earthquake happening in the early evening when many of the city’s residents had just returned home from work or were on their way home, the damage caused by falling buildings was compounded. Most the city’s southern portions were devastated and required a complete reconstruction from scratch afterwards. Some portions of the city experienced flooding, although the city itself was not struck by tsunamis. The air traffic control tower at Aleksandrgrad International Airport collapsed and a mudslide damaged much of the airport. Mudslides in northern Aleksandrgrad killed hundreds, and almost 70% of the city’s subway tunnels collapsed, killing thousands more. The city experienced systemic fires, often started by gas leaks or spilt oil, for several days afterwards, although the fires did not accrue significant casualties despite consuming much of the city’s wreckage. Small suburban towns on the Osarenkov Inlet were wiped out, and hundreds were killed at coastal towns on the Tsarevitch Sound.

With over 50,000 dead and almost 200,000 injured in a region home to just shy of a million, Premier Kirill Osopek declared “the greatest single loss of life in human history, the pearl of Alaska dirtied by the fury of nature.”

… Due to the earthquake occurring on Good Friday, in the United States and most of Europe, the earthquake is referred to as the “Good Friday Earthquake.” However, as Alaska follows the Eastern Orthodox calendar, in which Easter occurred a full month later and Good Friday fell on April 18th, the earthquake is often referred to as the “Earthquake of 1964″ or more ubiquitously as “the earthquake,” and Alaskans generally reject the name Good Friday Earthquake. In most of the world, the accepted name for the event is the Great Alaskan Earthquake.

There’s more where that came from – a labour of love to write it all out, as well.

The Sinking of the Titanic

Back in the late 1970s, in the heyday of the Edinburgh University Experimental Art Society, the largest project the Society ever mounted was a staging of Gavin Bryars’s piece “The Sinking of the Titanic”. This took a whole evening, and filled the McEwan Hall of Edinburgh University. The first part of the production represented the voyage of RMS Titanic; each member of the audience was issued with a ticket with the name of one of the original passengers, and they were able to mill around the hall as if on the liner itself. Certain key passengers, and all the crew, were allocated to actors, and the events that took place on the original voyage were re-enacted, up to the striking of the iceberg and the subsequent sinking. None of this took place on a stage, so individual scenes would only be witnessed by members of the audience who happened to be in that part of the hall, just as on the voyage, people would only have been aware of what was going on in their immediate environs.

At the point of the sinking, the audience were divided into the saved and the lost, and seated in opposite parts of the hall, so that they faced each other over the orchestra, which now played Bryars’s piece to conclude the evening.

It was hugely successful; every ticket for the single performance was sold. But it was an immense effort to put on. I remember that my part was the journalist WT Stead (who went down with the ship), and I have retained a slightly macabre interest in Stead ever since.

With the centenary of the Titanic’s voyage coming up next year, I imagine there will be a lot of commemorations, especially in Belfast, where the ship was built. Whether these will include anything like that performance in the McEwan Hall, I rather doubt.

But I was interested to find another musical connection: the First Symphony of the Swedish composer Natanael Berg (1879-1957). He was in the process of composing this work in 1912, when he read about the Titanic disaster, which so affected him that he remodelled the finale of his symphony. The movement had been a bright and breezy piece representing the pleasures and achievements of maturity (the symphony is one of those youth-to-age pieces). He retained the opening, but added halfway through an unexpected thunderstroke, sweeping away all happiness and leading to a concluding funeral march – symbolising how catastrophe can strike unexpectedly in the midst of joy. I’m not sure that musically the result is completely convincing … it is not as effectively managed as the similar descent into calamity in the Fourth Symphony of Franz Schmidt, for instance. But the symphony as a whole is still pleasant to hear, and it would be a nice touch if the Ulster Orchestra would mount a performance of it next year as part of the centenary celebrations.

Incidentally, earlier this month I visited an old friend in Belfast, now 103, who I believe is probably the only person still alive who actually saw the Titanic before it sank. As a small child she witnessed it on sea trials in Belfast Lough.

A hoax from 1790

Sometimes enquiries come my way for the most obscure events. One recent example concerned a supposed earthquake at Ormside, Westmoreland. The source is the chronology of British earthquakes at the back of Peter Haining’s book “The Great English Earthquake” (published by Hale in 1976). Haining cites Gentleman’s Magazine and states that two fissures over 200 feet long appeared into which houses and cattle sank, after a violent shock and a loud explosion. “Later investigators have wondered whether the event might have been a landslip,” wrote Haining.

In fact, Gentleman’s Magazine gives the location as Arnside, not Ormside, on the 6 March rather than 27 February. As a general rule, any report of a British earthquake swallowing up houses and cattle is usually a red flag that something fishy is in the air, and this is no exception. There is a nice contemporary account from the Newcastle Chronicle on 13 March 1790 (p2), which despite a disparity in date and location, is clearly describing the same event.

Some of the morning papers mention an earthquake having happened near Milthrop, in Westmoreland, on the 25th ult. which swallowed up six houses and some cattle – The inhabitants of that neighbourhood find, however, some difficulty in swallowing the story.

In other words, a fairly typical hoax event.

Hidden in plain view

There is a principle, famously exploited by Edgar Allen Poe, that the best place to hide something is in plain view – just make it appear that it is something else. There are many possible applications of this. For instance, suppose you have problems remembering a computer password. If you leave a piece of paper on your desk saying: “Password: Swordfish”, that would not be very secure. But if you had a scrap of paper with “Remember to buy milk” on it, would people guess that your password was “tobuymilk”?

One application that fascinates me is steganography, by which you can hide messages inside computer graphics. Not in the image as a visual component, but by hiding the message in amongst the data that makes up the jpg file. A few sentences mixed in with all the gobbledigook will not make any detectable change to the image.

In this way it would be easy for some villainous person to communicate with his henchmen even if security forces were eavesdropping on his emails and phone line. All he would need to do was this: first take some innocent photo, let’s say of bunny rabbits. Now – the message is “We strike next Tuesday week!” Using basic steganography software, insert this text into the jpg code. Next, go into an internet cafe and post the image onto one of the various internet public image gallery sites; preferably one where many people post to the same image stream. Your henchmen know which site to watch (arranged in advance), and they know to look for a picture of rabbits. Once they see it, they download it and extract the message. Since no-one can monitor every image posted on the internet, it would be impossible to intercept communications sent in this way.

I remember many years ago reading a novel that hinged on a supposedly unbreakable cipher. With many ciphers, coding and decoding depends on a simple-to-remember key – for the sake of argument, the word “capstone”. To start the cipher, you need to re-arrange the alphabet so that it starts with your key, like this:

CAPSTONEBDFGHIJKLMPQRUVWXYZ

This is then used to create the cipher. According to the novel (which predated computer cryptography) the wekaness of such ciphers tends to be that you have large chunks in the processed key that are still alphabetical – in the example above, FGHIJKLM and UVWXYZ. The plot spring was the idea that if you based the cipher on a completely randomised alphabet, this weakness would be eliminated and the cipher would be unbreakable. The problem is that a completely random re-arrangement of the alphabet would be impossible for a field agent to remember. He would have to write it down, and if he were captured, the existence of a slip of paper with the sequence would give the game away.

How to hide the sequence? The answer, of course, is to make it look like something else. You make the sequence this one:

QWERTYUIOPASDFGHJKLZXCVBNM

And now, if the agent is captured and found to have a portable typewriter (in those days) it would not incite much suspicion. Quite out of date now, but a nice example of hiding something in plain view.

Probabilistic programming

Given the importance of probability to modern seismic hazard assessment, I found it interesting to discover the other day the world’s only probabilistic programming language. It’s called Java2K and was invented by Gerson Kurz. As the name suggests, it’s sort of an update on the Java programming language, with which it shares some features. However, there are many differences, including the fact that it uses base 11 for all numbers, with a space representing 10. So if you see “10″ it is actually 11 in base 10, and “1 1″ is 1 x 11^2 + 10 x 11 + 1 = 232. Most instructions are represented by numerical codes, also all variable names must be numbers, which means that it is not possible to represent numbers literally. So to get the number 1, the trick is to use the random number function to generate a random number and then divide that by itself. To get 2, you would do this twice and add the results.

However, this is where the probabilistic element comes in. Any operation has only a 90% chance of returning the correct answer; 10% of the time it returns a random answer. Thus the more operations you use to generate a result, the more likely it is that one of them will malfunction. This obviously encourages good programming discipline, since it is necessary to incorporate rigorous checking within any program. The garbage collection is also probabilistic; memory is automatically freed at the end of the program, or at random intervals, whichever comes first. Again, this forces the programmer to write defensively, increasing the security of the code.

I have found a few Java2K programs on the web; here is a very short one as an example of what the code looks like. This program simply prints out the character “F”.

FOR-1 07=119 TO-/12 4DO/*/_\/12 4=13 2=*+*.+_.\+119 =11 6=*+_.+13 2/*/_\..
16 /125 =119 =125 =11 6=*+_.+_.+125 /13 2/*/_\/_\.+125 /131 /119 /125 /11 6/*/_\/_\/
125 =13 2=*+_.+_.\/119 =125 =11 6=*+_.+_.+125 /13 2/*/_\/_\.\/131 =119 =125 =11 6=*+_
.+_.+125 /13 2/*/_\/_\.+131 /119 /125 /11 6/*/_\/_\/125 =13 2=*+_.+_.\/131 =119 =125
=11 6=*+_.+_.+125 /13 2/*/_\/_\.+131 /119 /125 /11 6/*/_\/_\/125 =13 2=*+_.+_.\/131 =
119 =125 =11 6=*+_.+_.+125 /13 2/*/_\/_\.+119 /125 /11 6/*/_\/_\/125 =13 2=*+_.+_.\.\
.\.\./837=119 /12 4/*/_\/12 4=13 2=*+*.+_.\+119 /12 4/*/_\/12 4=13 2=*+*.+_.\.\
1 1 =*+837/119 /12 4/*/_\/12 4=13 2=*+*.+_.\/119 /12 4/*/_\/12 4=13 2=*+*.+_.\\.

Is the message getting through?

I was interested to see the following entry in the “Corrections” column of yesterday’s Guardian.

A report on environmental pressure groups calling on governments to abandon new nuclear power stations and large waste dump projects referred to tremors in India ranging up to 6.3 on the Richter scale. Seismologists no longer use this scale, we should have said magnitude 6.3. Similarly, a Pass notes item referred to an earthquake of 8.9 on the Richter scale. To clarify: the “Richter scale”, the logarithmic magnitude scale, was defined in 1935 to measure earthquakes in California. It does not, however, work for large earthquakes (greater than magnitude 7) or ones where the epicentre is further than 600km from the point of measurement. It was superseded in 1979 by the more uniformly applicable moment magnitude (Mw) scale.

It seems that reiterating this message has not been entirely in vain. However, to be completely accurate, one should say that the Local Magnitude scale was defined in 1935, which then became referred to by journalists as the “Richter scale”, a term not normally used by seismologists except when talking to journalists, and then under duress.

Why some tsunamis are worse than others at distance

An article on tsunamis on the BGS web page attracted a comment on Facebook raising the question as to whether the main tsunami threat to Britian might be from a flank collapse in the Canary Islands, not mentioned in the posted article.

To explain why such an event would be unlikely to pose much of a problem to the British Isles, here is a thought experiment. Imagine you have a concrete slab 2m long, 1m wide and 30 cm thick. Using a sling and a hoist, you suspend it horizontally, 3m above the surface of a swimming pool. Then you drop it. The slab hits the water flat side on. You can imagine the sort of huge splash that will make.

Now repeat the experiment, except this time, you hold the slab vertically, so that when you drop it, the slab enters the water end on. That’s going to make rather a smaller splash.

Third experiment: this time, you have ground up the slab and you have an equivalent weight of gravel. Drop that into the pool. Again, a splash, but of quite a different character.

It’s not the weight of material that determines how effective the splash is, it is the geometry of the object as it enters the water (and also the speed). An earthquake tsunami is rather like the face-on slab – except the slab is hitting the water from below rather than from above. Any sort of landslide tends to be either like the end-on impact or the gravel sliding in. It may still make a splash, but the wave is much more localised and not so good at travelling long distances. To produce a really effective tsunami, a volcanic flank collapse would have to involve the side of the mountain tipping over so as to hit the water flat on with maximum force, and as a coherent block. And that is not generally how such events happen.