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Determination of the
Height of Ol Doinyo Lengai
During the
BSES expedition to Ol Doinyo Lengai
the opportunity was taken
to measure the height of the Mountain of God by transferring the
height information determined using the Leica GPS with the high
accuracy Leica TPS1200 Total Station.
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Determination of
the Accuracy of a Navigated GPS
Point
Both the Survey and Geosciences
Fires were involved in collecting DGPS data to provide accurate
height information for the Gravity Meter Survey during the
expedition. This was carried out using Leica SR530 Survey GPS.
Garmin handled GPS units were also used extensively throughout
the five-week expedition for navigation. The opportunity
was taken to investigate the accuracy of the hand held
navigation GPS units.
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Geoscience Fire Projects
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Rationale and Scientific Objectives
The landscape of northern Tanzania
is dominated by the East African Rift Valley and the
Volcanoes of the Crater Highlands: it is a tremendously
inspiring place to study Earth Sciences. Ol Doinyo Lengai
is unique for its natrocarbonatite (sodium
rich) lavas. A
gravity survey of the Ol Doinyo Lengai was carried out with the aim of
constraining its density structure and providing information
about the composition of the volcano.
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Field gravity measurements
The gravimeter used is a relative
instrument: it measures the difference in g between two
locations. It was calibrated at the start and end of the
expedition against the known absolute value of g at
Arusha Airport. The calibration also allowed instrument drift to be checked and
calculated. Simultaneous (differential) GPS data were
measured by both the Geoscience and Survey Fires to obtain the accurate
height differencesrequired between the Gravimeter stations. |
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Gravity survey results
Fifteen measurements were acquired
in a profile almost 100km long across the rift valley.
This data was terrain corrected,
at Edinburgh University using a regional digital terrain model
for far zones combined with corrections obtained in the field
for local zones. These data fit well with existing data from the region and, once
the terrain corrections have been finalised will be supplied to BRG for addition to the regional database.
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Observations from the active crater of Ol Doinyo
Lengai
Ol Doinyo Lengai is one of the more
accessible active volcanoes in the world. The expedition was
fortunate enough to visit Ol Doinyo Lengai during a period of minor
volcanic activity. |
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Acknowledgements,
References and
Appendix
Acknowledgement of those who made the
BSES expedition possible and a success.
References to material used to write the reports and and Appendix
detailing the equipment used and the lessons learned. |
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Lengai Logistics
One of the aims of the expedition
was to maintain a continual presence on the summit of Ol Doinyo
Lengai for as long as possible. |
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Science Report in Acrobat PDF format
To view this
file you will require
Acrobat Reader. If you do
not already have a copy, visit the
Acrobat site to download the
version for your operating system.
This is a
large file so may take some time to load. |
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