Harrow and Hillingdon Geological Society

Life of a Seismologist

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Hello All!
This is the actual working life of a seismologist…………

Actually, there has been quite some excitement – largely the trip to Georgia (that’s Georgia, the state in SE USA, not Georgia in the Caucuses. So not quite THAT exciting….). This was a field trip to do a service run of the seismometers that have been put out by a team including my supervisor. (For anyone who is interested: the reason for this particular array is that Florida used to be part of a different continent (Gondwana) pre-Pangea, and the aim is to look for how the suture extends down throughout the lithosphere).

There are some 40 odd seismometers set up over all of Georgia and a few down into Florida. (We are planning on putting out another 40 come May, so I should have much stronger digging muscles by June!) The servicing run is primarily to collect the data that has already been recorded, as IRIS, the organisation that lends out the equipment will only provide 4Gb of memory for each station. Given that the sensors cost some $25,000 a piece, and the control boxes at the sites are some $12,000, you’d think that shelling out for an extra couple of gigs would not be a big deal. I think it’s probably all an excuse to make sure the sites have a check up every six months...

The team for this run was me, Julia (my friend who’s house I stayed at), our advisor Karen, and Amanda – another PhD student in Julia’s year who is a rock-squisher. But more importantly, pretty strong. We went around in two teams of two, led by Karen and Julia (who was here last May, helping to put out some of the stations).

So, to help you picture the scene… All of the sites have to be on farmland in somewhere that is as far as possible in the middle of nowhere – nothing gets in the way of a nice earthquake so much as pesky, noisy humans! So imagine driving under the bright blue skies, a nice 18° or so by lunchtime, picturesque pecan groves as far as the eye can see. Inside the car, things are a bit more hectic – equipment, maps, a laptop scattered about the place, while the passenger struggles to put “the middle of nowhere” into the satnav as a valid destination while loading and examining the data from the previous site to make sure that we don’t need to go back. Cereal bars, crisps, carrots, dip, pretzels and chocolate also adding to the general confusion – having learnt our lesson about trying to find somewhere to buy lunch on the road in rural Georgia on the previous Sunday.

(The two satnavs we have each have their own idiosyncracies. One has pretty much given up on life, and turns off every time the power cord is so much as knocked. Which wouldn’t be too bad, apart from the fact that it decided to reset every time it switched on, leaving us dangling for about 3 minutes every time. Which can take you a long distance when you’re on the road… The other one didn’t have the capability to put latitudes and longitudes in, so it literally did involve searching the aerial photos we had for the nearest cross road of roads that actually had names, and then navigating by clumps of trees. At least there were clumps of trees to navigate by – can you imagine the difficulty of trying to that in Devon? It’s by the slightly bushier bit of hedgerow next to the sheep field? One time we were trying to get somewhere, and the satnav had a hissy fit, and we guessed while it reset itself that we wanted to take a turning. Which turned out to be through an orchard with a sign up saying DANGER DO NOT ENTER. So we swung a three point turn, as these guys who had been lounging about started yelling at us. So Karen calls out, “Sorry, we were just a little lost,” and one of the guys comes up trying to help us. The guy is definitely a little the worse for wear, especially for 1pm, and completely decked out in bling. And leans in on the window, so we are stuck talking to him. He did seem to be genuinely trying to help, asking us what county we were headed for (he asked that question about 6 times, and I genuinely never understood which word he was using. Good thing Karen’s partner is from North Carolina, so she’s used to this kind of accent…). And Karen was not prepared to explain about the seismometers, and that we were headed for W32 in the middle of nowhere. Nor was she prepared to say yes, thanks, to the guy’s directions, and then blithely drive off in the opposite direction, that we were relatively sure was the right one. And I was being no help, because, quite apart from not being able to understand what the man was saying, I had noticed that he genuinely had Silver Plated Teeth. So I had to look studiously into my lap and try desperately not to giggle….)

Eventually we manage to find our way to the proximity of the site. Then it becomes a game of Spot the Solar Panel – which have a dual function of keeping the equipment charged, and acting as a large shiny thing sticking out above the vegetation (hopefully), making it easier to spot the things. After driving back and forth for a while around what we are sure is the right field (often stopping and reversing along the (dirt) state road, because there is literally NOBODY around), we spot the thing, and go for a not-at-all off road adventure through the field. (When we were picking up the rental cars, our advisor was asking about whether or not they were 4WD. When the guy said no, she asked how good they would be for going off-road, and Amanda, who had had to sign the agreement for the other car, had to hurriedly cut in with a reminder that off-road was strictly not allowed under the terms of the rental. And Karen back-tracked, saying she meant the dirt roads. Which was ok, because the rental car guy kind of puffed up a bit with pride, and said “Well, we haven’t got around to paving all the roads down here in Georgia.” I guess sometimes you have to be proud of what you can…)

The site is set up as follows. The solar panel is running power into what appears to be a big cooler box, the bottom few cm or so of which are buried into the ground. This is covered by a big bit of plastic sheeting held down with bricks. And, if it was one of the earlier ones to be put out, and so buried almost up to the lid into the ground, also probably covered with a fire ant nest. Quite often, the intensity of the summer of Georgia sunlight has melted the plastic onto the top of the box. The actual sensor is buried under the ground by a few feet. Usually covered by a give-away patch of bare dirt rather than vegetation. However, at some of the sites, several equally boring patches of dirt had to be scrutinised before we decided which one the sensor was under.

And, as a special bonus, the dry, dark folds of the plastic sheeting provided the perfect habitat for spiders. And in this part of the States, the spiders who are going to claim such prime spots are Black Widows. The good thing about Black Widows is that they are very large, and a very shiny black, with a bright red patch on their tummies, making them pretty easy to spot. The bad news about them is that they look like that, which is actually a pretty scary way for a spider to look (and I’m not even predisposed to be scared of spiders!). And that quite a lot of the previous plastic sheeting was black and shiny. And the red spot is on the bottom of their abdomen, meaning that they have to be upside down for the red to give them away…

Also, probably far more dangerous than the spiders, it was also hunting season. And we were out in the field from about 8am to about dusk, in some cases in pretty small clearing surrounded by trees. Where we had been warned by the owners of the land to be careful of hunters. But apart from finding the occasional shell, or hearing the odd bang, we didn’t actually run into any problems.

The actual servicing took about half an hour per site (by the end of the trip, assuming nothing had to be replaced), and basically involved switching out the memory cards, checking nothing had been gnawed through, and that everything seemed to be functional (which, given that what we were servicing was seismometers, involved checking they could pick up vibrations. i.e. jumping up and down, and seeing how big a peak you could make!), and that none of the settings of the control system had gone haywire. Also, in some cases, cutting down any pesky vegetation that was getting in the way of the solar panel. Although, turns out that the solar panels are surprisingly resilient – one had a bullet hole straight through it, and seemed to be working just fine!
So bring on the return trip in May……………………

Emily Hopper

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