Today was the last day in the caldera. The end of our time here has almost arrived. I have had the most amazing time, met some amazing people who I will stay in touch with and the caldera has most certainly been the hardest field location I have worked in to date. I can’t wait to come back next year! I suspect there will be a few tears tonight and tomorrow when we leave. Most of the staff are coming in tonight to say good bye.
Me, Jenny, Florence and chef Samuel. This was a teary good bye, thanks to Flo!
Security check point!
So today was a case of finishing off in the caldera. It is always advisable when doing fieldwork, to allow a day or two of finishing off. It gives you time to revisit locations that may have confused you in some way, or add to the data pool. Anything that you feel the need to readdress. Once you have left you can’t go back!
Firstly, we went to visit Great Rift Drilling’s Rig 1, owned by Cluff Geothermal, now that it is fully constructed. It’s a much smaller set up than the rig we visited on Day 2. Hydraulics are used to control the drill string in this case. It is much more compact, takes 4 days to take down, move and reconstruct; compared to the 21 days for the larger rigs owned by GDC. They also cost a tenth of the cost to move compared with the GDC rigs. The amount of water used is vastly reduced with these rigs as more often than not, air is used to lubricate and to raise drill cuttings to the surface. The only time water is used to excess is when the lithology is very loose or unconsolidated. This is when cave ins, or sluffs, occur within the drilled hole. Mud contributes to keeping the lithology where it is, stopping debris filling the bottom of the hole. In this instance, when the water and mud returns to the surface, it is sieved so it can all be reused. These rigs can drill to 3000m, in comparison to 7000m for the larger rigs. However at Menengai, the maximum depth is 3200m, which was a one off. The rig can also case to 2000m. It is packed with wireless technology, meaning it takes less manpower to work and control and it is overall more accurate. All in all it is a much more cost effective piece of equipment and brilliant with it! There are currently four in the world, so the viability of the rig in this location is being tested. It is an amazing bit of kit, incredibly impressive!
Cluff Rig, Great Rift Drilling 1
Cluff Rig, Great Rift Drilling 1
My remote control toy is bigger than yours! At the drill controls.
While talking to Jeff the rig manager, he told us about a problem they encountered while drilling the proposed well MS-14. They took the drill to 600m and began to cement the hole. But the cement didn’t seem to do its job, it just seem to disappear in to the hole. When he described the cuttings that were coming to the surface it sounded like tuff. The description was brown light weight pebbles, sometimes broken up. It may have been the pumice fall out associated with early stages of tuff deposits. The porosity of this could certainly explain why the cement didn’t do its job. It would also potentially explain why we haven’t seen deposits within the caldera associated with its collapse.
The next task of the day was to return to the fault in the NW corner of the caldera, discovered on Day 10. As access to the caldera walls has been limited I wanted return to this location to try and collect more structural data. More fractures were measured. We also discovered a fault plane that had a different trend to the one measured on Day 10. It had the same pale hardened coating of what is likely to be clay. It also had large slickenlines which were also measured. I am still playing around with what this fault might mean as it hasn’t been recorded in any literature. The different trends of the fault(s) may be because the fault is scalloped and is part of a small collapse of the NW crater. Or it may be two different faults and have nothing to do with any collapse. What we did notice was how unstable the area is. Since our last visit just 9 days ago, more of the cliff has collapsed on to the road making access with the car even harder. So we didn’t spend too much time there.
This was followed with a quick visit to the fumaroles by well MW-10 where we cooked breakfast. I just wanted to collect samples of the altered rock to analyse. We also went back to the second set of fumaroles discovered on Day 13. I wanted to check the surface above the fumaroles to see if there were any emanations higher up. There were small ones that weren’t too hot, the alteration of the rocks was less and they were close to a large fracture that may have been a low energy fissure. There were also elongate depressions along the surface that may be fractures that have not quite propagated to the surface, but the surface trace is due to land subsidence in to the fractures.
I have unexpectedly got involved with Ujima Foundation while here. An amazing charity that gives young men and women from the local communities a chance to train in the hospitality industry. The trainees are usually those who have had a struggle in life and may never have had the opportunity to escape from hardship if it wasn’t for the foundation.
One example of many is found with Lillian. A young hard working woman who loves her job here at our accommodation, Maili Saba Camp. Her father was abusive to her mother, but her mother remained believing her two girls were better in a home with both parents. At 16, her father passed away, a weight had been lifted. A year later her mother passed away also. Lillian was left to support her younger sister and pay for the home. She down sized property, giving her a little money to live on while working at the markets selling products bought from the local farmers. A friend one day mentioned the foundation and got Lillian an interview. Despite forgetting the interview and having to run from the market, then forgetting she still had her apron on, she got the position to train in hospitality with the foundation supporting her.
Tomorrow, we are off to Lake Bogoria, in part a day off, but we won’t be able to help ourselves, we will still find geology to look at. There is little to no understanding as to why the flooding has occurred and Lake Bogoria is not the only lake that has flooded. All the EAR lakes in Kenya have flooded and some in Ethiopia are demonstrating the same. One thought is the continuing stretching and thinning of the crust has resulted in fracture and/or fault propagation downwards in to the aquifers. Hydrothermal fluid contamination has been recorded in two lakes in Ethiopia.