Uncertainty in mapped geological boundaries held by a national geological survey:eliciting the geologists' tacit error model
It is generally accepted that geological line work, such as mapped boundaries, are uncertain for various reasons. It is difficult to quantify this uncertainty directly, because the investigation of error in a boundary at a single location may be costly and time consuming, and many such observations...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2015-06-01
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| Series: | Solid Earth |
| Online Access: | http://www.solid-earth.net/6/727/2015/se-6-727-2015.pdf |
| Summary: | It is generally accepted that geological line work, such as mapped boundaries,
are uncertain for various reasons. It is difficult to quantify this
uncertainty directly, because the investigation of error in a boundary at a
single location may be costly and time consuming, and many such observations
are needed to estimate an uncertainty model with confidence. However, it is
recognized across many disciplines that experts generally have a tacit
model of the uncertainty of information that they produce (interpretations,
diagnoses, etc.) and formal methods exist to extract this model in usable form
by elicitation. In this paper we report a trial in which uncertainty models
for geological boundaries mapped by geologists of the British Geological Survey
(BGS) in six geological scenarios were elicited from a group
of five experienced BGS geologists. In five cases a consensus distribution was
obtained, which reflected both the initial individually elicited distribution
and a structured process of group discussion in which individuals revised
their opinions. In a sixth case a consensus was not reached. This concerned a
boundary between superficial deposits where the geometry of the contact is
hard to visualize. The trial showed that the geologists' tacit model of
uncertainty in mapped boundaries reflects factors in addition to the
cartographic error usually treated by buffering line work or in written
guidance on its application. It suggests that further application of
elicitation, to scenarios at an appropriate level of generalization, could be
useful to provide working error models for the application and interpretation
of line work. |
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| ISSN: | 1869-9510 1869-9529 |