Showing posts with label fieldwork. Show all posts
Showing posts with label fieldwork. Show all posts

January 29, 2012

Not all geophysics fieldwork invovle that much exercise

Pulled array seismics being one of them, especially when I am the only one on the team to take care of the stuff up in the vehicle that we use to pull it all.

I have been trying to do a bit of exercise at the hotel rooms, can be difficult though to motivate yourself after a long day at work.

January 30, 2010

Off-road driving

Doing geophysics fieldwork often involves at least some degree of going away from the roads with different kinds of vehicles and/or equipment depending on what you are doing.

Off-road driving is something that you really don't learn well by reading about it, getting good at driving in the terrain is something you learn by experience, however this experience can be pretty "expensive".
I myself have spend many many hours reparing damages and getting stuck vehicles freed, I guess I have learned a bit in the process.

Here is a few tricks that might be of help:
  • Tire Pressure: Lowering the tire pressure is a help in many kinds of terrain, but not all. I have been amazed at how much it helped to keep a car afloat while driving in sand. Keep in mind that with lower tire pressure you also increase your risk of punctures and don't go out driving fast on tarmac in a vehicle with low tire pressure.
  • Speed: Often the best way to get through bad difficult terrain is to keep the vehicle moving at good speed, if you feel the vehicle is starting to get stuck don't take you foot of the gas pedal or you might not be able to get out again 
  • Stuck: If you have come to a stop in deep mud or something similar don't just spin the wheels, you will just bury them deeper, often what will get you out is moving the wheels very slowly or in bursts to make a rocking motion until you have the vehicle moving again. Use whatever you can get your hands on to free the vehicle: Sand, branches, stones etc. It all might help get the vehicle up where it again has something solid that the wheels can grab. Another trick to be used with great caution is to tie something like a long tough log to the wheels (especially if you have a vehicle with big rear wheels like a tractor) and rotate the wheels until either the vehicle is standing on the log or if more suitable until you have moved half a turn of the wheels.
  • Training: Getting out and driving on slippery winter roads is great training for driving in the terrain, so on days where the roads are particular slippery get out and have some fun. Big empty parking spaces and gravel roads do especially well for this.
  • Towing: Very much depending on the situation there is some point where trying to free a vehicle on your own is no longer the right way to go, sure you might be able to do it, but only at great risk to the equipment, personnel and costly hours spend, keep in mind that there is a time when calling for help is the way to go.
  • Topography: Everything gets a lot more difficult when you go uphill, try to use the terrain, find places to drive where the slope is less steep. In muddy terrain try to keep up on the high areas or close to drain channels and such where the ground is not as wet.
  • Trailer: Pulling a trailer or similar through terrain increases you risk of getting stuck and makes it a lot harder to free a stuck vehicle. Bring along chains or ropes and when stuck, unhook the trailer move the vehicle out and then tow the trailer from better ground.
  • Weight: A pretty obvious thing, but it really is worth cutting down on the weight as much as possible. More than once I have been able to free a stuck vehicle by unloading it.
These are just a few things from the top of my head, surely there's lots of better reading to do on the subject than this, but best way to learn off-road driving is by doing.
It's great fun by the way ;)

May 24, 2008

SAS Survival Guide a book for fieldworkers?

This being the only survival book I have ever read I am not really in a position to judge if it is a good book or not, just surfing over a few reviews on the internet shows me that there are some people who think that there is some things in this book that is inaccurate, but also a lot of people who have a lot of positive things to say about it.

I myself have learned a whole lot of things by reading this book and among the things I have learned a lot of them have come in handy when doing geophysics fieldwork. I often take the book with me and try to learn to get better at identifying the different plants that it talks about when I am working outside in nature anyhow.
This is something I have found is a good way to avoid getting your mind all to much mixed up by being out working all day long every day for months in a row, setting myself a goal to learn something while being out there, something that perhaps is not all to related to the work I am doing. When I am out working with someone who has a lot of knowledge in some field, like for example a forester student who can teach me about trees or someone who knows a lot about birds, then it is a given what it is I am trying to learn. But quite often I am out working on my own or with someone who doesn't have any specific knowledge I am interested in. In such situations trying to get to know new edible or poisonous plants, knots or something like this of which there are plenty to get started with in the book that can be both very good skills to acquire while it also keeps me sane.
Often bringing a book into the field is not practical, but that doesn't keep me from bringing home small samples of plants and trying to identify them in the evening and such

I have found that it is generally a good idea to give it a bit of thought how I am going to stay "sane" if I know that I am going to be on a longer assignment, it actually makes it a lot easier to get the job done and do it well if you have something else to think about than the work itself.

September 14, 2007

Drilling

Drilling's isn't the first thing that comes to my mind when I think of geophysical methods and I guess it is more geology and geophysics, never the less that is something I work a lot with these days and it is a method that should never be ignored.

Drilling really seems quite straightforward and it basically is very simple. Making a hole in the earth with pretty much the same radius all the way down.

In general something can be said about drilling as such when compared to other methods:
- You only get information from one horizontal point (or maybe more accurately a small area with the radius of the drilling and perhaps with certain log-methods some information from the earth surrounding the drilling but I have yet to see a drilling to be used as more than a point information for all practical purposes) to the depth that you drill.
- You usually get extremely accurate information, when used with other geophysical methods drilling information is often used as very certain information which is used to check data and improve on the processing of data acquired through other geophysics methods.

There are many ways of doing drilling's, each with it's advantages and disadvantages.

One method is using a real drill head and turning/pushing that down the earth, the big advantage of this is that if you pull up the drill every time you have drilled the depth of the drill head you get a pretty undisturbed sample of the earth at that depth, that makes it possible to make very accurate description of the earth. One of the big disadvantages of this method is that it is far from always possible to do this, the harder the earth is the more force is needed to turn and push down the drill and the more strength is required from the drilling equipment.
This method is what is for example usually used for geotechnical investigations to check the underground before a building is build and to decide what kind of foundation is needed, for this purpose the drilling's need not be much deeper than to the layer which can carry the weight of the building which often here in Denmark means only a few meters for a normal house even though sometimes deeper drilling's are needed even for small houses depending very much on what is found in the drilling.

August 09, 2007

MEP also known as static DC-profliling

I thought I would write a bit about the things I work with, hopefully this will only be the first of a row of posts about different geophysical methods.

The geophysical method I work with the most is called MEP, Multiple Electrode Profiling, I think in some areas this is better known as static DC-profiling.
The idea behind this method is to send an electric current between two points on the surface of the earth and measure the potential difference between two other points which then will give you some kind of resistance measurement.
Now this resistance says something about what it is you are sending the current through. Of course you measure higher resistance the further apart the electrodes are, but when you do some calculations on this you find out that this can be taken out of the equation by dividing by something called the geometrical factor, you then have something that is measured in ohms/m, called relative resistance which if you stand on a "homogeneous halfspace" (a flat earth consisting of the same material) will give the same output no matter how you arrange the electrodes. Now the earth is not a "homogeneous halfspace" but this relative resistance that you measure says something about what it is you send the current through.
Another thing that is being used is that the further apart the electrodes are, the deeper the current will run into the earth. So this way you can get a lot of information about the resistance of the earth. By doing measurements with different configurations of the electrodes you get ever more information on the resistance structure of the earth.
There are almost always more than one resistivity model that will fit data, but if you also have some other geological information and put on some boundaries on what kind of model you accept (like for example the 1-d model which says that the earth is composed of horizontal layers, which often is close to true) you can get a pretty good idea of what is beneath the surface.

The way this is done practically is most often (at least in my experience) with some special equipment from a company in Sweden, Abem, the company is closely connected to the university in Lund.
Usually you lie out 400 meters of multi conductor cable, connect that cable to the ground using spears that you connect to the cables outlets and then let the machine in the middle send out current and measure potential differences on a lot of preprogrammed configurations. When it is done you move 100 meters of cable to the other end of the line, move the machine back to the middle and let it measure again, then move another 100 meters and so on and on.

One of the good things of this method is that you can measure in almost any terrain as long as the fieldworkers are able to lie out the configuration in a straight line (can be a bigger challenge than what you might imagine, but it is can almost always be done). All the equipment and work can be done by two men carrying the equipment.
With the 400 meters configuration you can usually get reliable data down to at least 50 meters depth and sometimes even 200 meters depending a lot on what structure the underground has. As with almost all of these method the deeper you get the less resolution you will have on the structures in the underground.

July 03, 2007

Handling an unstable income

Geophysics fieldwork is often a very unstable business, at times there is enough work to keep you busy all day around, cast gushing in your account and then there are these periods where there hardly is any work around at all, and with that no real income.
One thing that controls this is the seasons, a lot of the manual geophysics work is often done in spring and fall (see previous post about crops for part of the explanation why), other things that may change this is the financial situation for those that order the work done and then again the company where you are working for the most might not win the big assignments that you are were counting on etc. etc.

So how to handle this, not really being able to count on a stable income?

Now I am not an expert on this, far from actually, but still I thought I would share a few thoughts on this subject with those who might have interest in this.

One thing that sure helps is to have a big bag of money lying there for the periods without income.
This is something that needs to be thought of in the periods where the income is really good, don't spend it all at once, tug a bit aside for times when work might not come as easily.
Different unemployment insurances might also be something that could help, I myself prefer to steer clear of as many insurances as possible (easy for me to say living in a country with free health care ... a health insurance is something I would avoid living without if I could) and try my best to be self insured. If you wonder why then take a look at the big office buildings (palaces might be a better word) and the many many workers in these buildings of the insurance companies, where do you think these money come from?

I don't find it easy at all handling this financial instability, but one thing that helps in handling this is the art of making a budget and working on sticking to it.

Another thing that helps is to have some kind of back up job that you can fall back on when geophysics work is getting slim. At this time in Denmark that is no problem at all, there is more work than there are hands to do it, but this will not always be the case. How you get one of these jobs to fall back on isn't something that I have a recipe for ... having an open mind never hurts, for example the tourist business has a lot of their main seasons in the summer and winter which fits nicely with the geophysics fieldwork in spring and fall.

May 26, 2007

The problems of crops and other difficult terrain

This week I have been out doing a little geophysics job and one particular experience from this week inspired me to write this post.

Things were as such going smoothly with our fieldwork, it looked as if we might even be able to pretty much finish two days work in one long day, we were slowly moving south with the stuff we were doing. Then it was that I saw something that made me right away forget about getting this job done in one day ... rape ... about the hight of my head and entangled as only rape can be. We were able to move all measurements but one with the first method we were doing in the area out of the area with rape but had to take some serious detours and the one measurement we had to do in rape took about 3 times the time that one would otherwise do in not so annoying crops.
The next day we were also moving through the same rape, giving us quite a few problems also but this time we were doing PACES which involves a puller on crawler tracks which cleared a way through the lines we were moving on, still the part of the lines that were through the rape did take something like double the time and the measurements were of much worse quality due to the rape lying down were making the earth contact worse.
So I by now really understand why anyone who is just a little experienced in planning geophysics fieldwork try to push the fieldwork so that it can be done when there are as few crops on the fields as possible ... not only because of the problems that the crops (the worst crops here in Denmark being rape, charlock and corn but others can also cause problems). There are times when the job just can't be pushed to the right seasons like the job I did this week ... with the weather we have had here in lately the crops are at least two weeks ahead of what they usually would be.

Again certain kinds of terrain take even more time than any kind of crops, the most extreme experience I have had was when we were lying some CVES lines through a swamp, it took an entire day to get done 1/5 of what we would usually have been able to do on a day.
Other things causing problems is forests, some method just can't be done there (or in "worse" terrain) while others like CVES just takes a lot longer time to do and requires experiences fieldworkers to get good results.

I have been thinking of maybe developing a way of estimating the problems caused by different kinds of crops and terrain for the fieldwork that needs to be done, this would probably be a useful tool for the people put in charge of planning geophysics fieldwork. I have not seen this done anywhere yet, but I would be grateful if someone could point me to such a resource if it exists ... if for not other reason then because it would be interesting to see if my experience from practical fieldwork fits what some theoretic work is predicting.

May 03, 2007

Sudoku

I have just been spending 4 hours on a 4x4 Sudoku puzzle where I here after 4 hours sitting in front of the computer find that I have made a mistake and can't find room for the 5 that needs to be somewhere in a quadrant. I can identify in which quadrant the mistake is, but I end up figuring that 4 hours is enough time spend on this.

Sudokuy is really very fascinating, the 3x3 is usually solved in less than 30 minutes, it is a nice way for me to relax, but I have only once had the patience to solve a 4x4 sudoku, that took me something like 4 hours back then.

I have made myself a little programming task of making a Sudoku program of some kind, Sudoku is something that computer programs are much faster at solving than a human brain will probably ever be ... at least if you have anything that resembles as much computing power as what has the everyday person has easily been able to get for the last ~25 years.
Still to make this program I need to learn Java better which right now is the language I am trying to motivate myself to get learned, it's been months since I last did spend time with this, it will probably have to wait until winter like so many other projects involving a lot of sitting down.

Right now I am out working a lot in with geophysics and related things which has me very physically active, if I was to sit down to much now I would get out of shape, it has been hard enough to get myself into physical shape again after the winter, I am kind of planning not to allow myself to get as much out of shape again like I did last winter.

February 23, 2007

A bit about my field equipment

I have just been spending a bit of time writing about field equipment primary from my years of experience in geophysics fieldwork.
The page is far from done yet, I plan to write a lot more, primarily to help myself remember everything when I am in a hurry getting new equipment or packing for field trips, it has so far happened quite often that I do not have many days between field trips.

February 09, 2007

Choose the right service to provide your weather forecasts

I just came upon this interesting article on /. pointing to a statistical evaluation of the forecasts from 10 different internet forecast channels that have weather predictions for the USA.

Pretty useful for anyone living in the USA to try and figure out where to go for their weather forecasts I would think.
I am happy to also be able to give the advice in this case, stay away from Microsoft products, MSN weather turns out to be pretty much the worst in that evaluation.

Still I think getting to know the basics of meteorology and then study what is going on at the moment and why the predictions were made the way they were is an even better option if you are really dependent on knowing the weather. That way you have an idea of possible scenarios and know how to read the skies and other signs when you are outdoors and can take your precautions.

December 28, 2006

Distance measurement on Google maps

Sure there are lots of little tools on the net for measuring the driving distance using asphalt roads, but sitting here trying to figure out if I can make a walk from Ans to Kongensbro along Tange sø and Gudenåen and if I shold take the bus back to Ans when I get to Kongensbro or walk back again, these tools were pretty useless.

That is when I realized that google maps is perfect for this, someone must have build something to measure distances along a chosen path. I am sure there are other tools out there but this one solved my need.

The distance from Ans to Kongensbro should be something like 7 km. along the water so I should be able to walk out and back home before the sun sets if I get out the door now. ... which means I should stop writing and get moving :)

December 23, 2006

Hiking boots

My hiking boots are very important to me, having hiking boots in good condition means a lot when working as geophysical fieldworker, where I often have to walk up to 50 km. a day with heavy equipment with in all kinds of terrain.

In the perfect world I would every day when I return home from work clean my boots in water and every now and then give them a bit bigger haul over. I have gotten better at getting this done with time, but still I am not as good to my boots as I wish I was.
If it wasn't for the wear hiking boots get better the longer they are used, so good maintenance gives you good boots for a longer time.

I found this page which contains some nice advice on taking care of hiking boots, so far it's the best page I have found with advice for taking care of hiking boots but then again I am not an expert on this

I some time ago heard the advice of soaking a pair of new boots in water and keeping them on your feet all day for a long walk and then stuffing them with newspapers over the night, this should give a much better fit and save you from many hundred kilometers of walking in the boots.
I tried this back in August with a new pair of Lowa boots and it actually turned out to work much better than I had expected. Sure it still was a new pair of boots, but no blisters, and I had no problems with my feet during the months tough work that I was doing after this. I will follow this advice again next time I am to get a couple of Hiking boots.

Another thing that I have found is important is the sole, I have found investing in a quality sole like for example this one is well worth the money. After having replaced the not bad standard sole in my hiking boots with these soles I feel a lot less tired in legs and back after a tough day at work.

November 17, 2006

The beauty of Thy

I have the last few days been working in northwestern Jutland, being outdoors all day. I will be going back in a few days again to complete the job there.
The area is really beautiful, it has been quite windy and the waves at the shore of the north sea shore is truly amazingly beautiful, make you feel how little I as a human am compared to the forces of nature. I think it is healthy for me and my emotional welfare to get this experience of how little I am compared to the forces of nature.

My boots have served me well, the groundwater table is apparently quite high in the area and there lot's of area with shallow water, we are moving all around the place outside roads and in all kind of terrain out there and I would often have had wet feet had it not been for my Lowa boots that I do my best to treat well in spite of the tough use, they pay me back by keeping my feet dry which is something one really learns to appreciate working as a geophysical fieldworker.

June 23, 2006

Swamp walking

Yesterday at work we had to pull some cables through a swamp.
It was an interesting experience, besides the fact that I have been removing quite a few of these little bloodsucking beasts (I don't remember their english name) afterwards and my feet, socks and lover legs were soaked after an hour in there (I worked there for at least 7 hours), I really enjoyed it.
I had to cut myself a way through the plants, which is quite a special feeling. Had I not brought a compass in there I am not sure I would have been able to find the right way through it all, the GPS also gave up as it "needs a clear view of the sky" as it kept telling me: Yeah right budy, I am in the middle of a swamp how do you suppose I should find clear sky ;)
At times the ground was so soft that I had to put out dead wood to make temporary bridges over these places, while at other times I had too jump from place to place where the ground could carry my weight.

There are far to few places like these left in Denmark but actually we have a few of them close to my hut. I think I will spend a bit of time exploring them in the future.

June 17, 2006

Growing a darker skin and Kvistur getting new horseshoes

Finally I have a little time to write here again. I have not had the opportunity to write here because of a lot of work these last days.
It has been quite enjoyable working even if also quite tough, especially because of the heat. I think I have been drinking at least 12 liters from Tuesday to Thursday this week. Especially Tuesday I consumed extreme amounts of water, I was working in a corn field, with the corn at the height of my hips. There was almost no wind and the temperatures in the shade was well above 25 degC, inside the corn it was a lot hotter and when we were trotting a new path through the corn (which we did pretty much all the time) I felt how the heat was rising from the ground and corn up past my face, making it hard to breath. Often I was also dragging more than 50 kg. along. A pretty tough, but at the same time efficient way to get a darker skin color ;)
I don't think I have ever enjoyed an ice cream as much as the one I bought when we had a little break.

It is really nice to be able to work again after having been idle for a month because of my ankle. It is a bit tough as I am not in the physical shape I was in before I sprained my ankle, but the endurance and strength is coming back to me pretty fast.

Kvistur has gotten a set of nice new shoes yesterday, his hooves are not that strong. He had lost one shoe while I was away and the hoof that he had been walking on was pretty worn down, the hot weather these last days have not made things better, with the hoof getting dry. I feel a bit bad that I was not there to help my horse with his dry hooves and the lost shoe.
The skilled farrier that comes here did a really good job with this damaged hoof. Kvistur behaved OK getting new shoes, even though he did protest a few times when he got bored. The farrier handled it very sensibly, being all calm along the way and that also made it a lot easier for me to calm down Kvistur.

June 12, 2006

Good morning /.

Well this morning I awoke to find that for the first time (and the second time I submitted anything) my submission to /. composed yesterdays morning had been accepted during the night (DK time).
So this probably means that there will be a few people from /. clicking over on this site, they are just as welcome as anyone else, but I doubth they will hang around much longer than anyone else, I think I generally write blog posts that are a bit to long, a bit to boring and with to little content ;)

Later today I will be picked up by one of my co-workers, we will be going away for full time duty for a few days where I probably will not be able to write in here. I will be trying to put in as many hours as I can pressure out of my foot and my co-worker, as there are other jobs of the same type waiting for me if I get this over with fast enough.
This is the season where there is plenty of work for me, so I'd better earn a little extra to make it through the winter where there is not as much geophysics work around.

May 14, 2006

Preparing for the winter ...

Now that I am not able to run around as much I have again started working a bit on my computer-skills. A bit of what I have been playing around with is a bit of CSS on my homepage. There probably isn't much to see on the page itself other than a change of margins, but the code behind the page has gotten somewhat "cleaner".

In my current main line of work (geophysics fieldworker) there isn't all that much to do in the winter, and this slashdot article and especially the comments to it has me thinking that maybe it is good that I probably would do well to keep my computerskills sharp while I try to improve on them also, it might be a good idea to also be able to have at least a decent income during the winter.

This morning I have been taping up my ankle as well as I could, I finally found the sportstape for the purpose and I think this will make it possible for me to take care of Mia today, the ankle sure feels better this way. I was not able to find other solutions than me taking care of Mia today, hopefully we will be OK.