none
10.1190/1.1442303
Society of Exploration Geophysicists
Society of Exploration Geophysicists
186
4727086
5981
2020101514350900319
10.1190
20201015T21:35:30Z
20021011T20:01:07Z
1997
GEOPHYSICS
GEOPHYSICS
00168033
19422156
03
1987
52
3
Occam’s inversion: A practical algorithm for generating smooth models from electromagnetic sounding data
Steven C.
Constable
Scripps Institution of Oceanography, University of California at San Diego, Mail Code A030, La Jolla, CA 92093
Robert L.
Parker
Scripps Institution of Oceanography, University of California at San Diego, Mail Code A030, La Jolla, CA 92093
Catherine G.
Constable
Scripps Institution of Oceanography, University of California at San Diego, Mail Code A030, La Jolla, CA 92093
The inversion of electromagnetic sounding data does not yield a unique solution, but inevitably a single model to interpret the observations is sought. We recommend that this model be as simple, or smooth, as possible, in order to reduce the temptation to overinterpret the data and to eliminate arbitrary discontinuities in simple layered models. To obtain smooth models, the nonlinear forward problem is linearized about a starting model in the usual way, but it is then solved explicitly for the desired model rather than for a model correction. By parameterizing the model in terms of its first or second derivative with depth, the minimum norm solution yields the smoothest possible model. Rather than fitting the experimental data as well as possible (which maximizes the roughness of the model), the smoothest model which fits the data to within an expected tolerance is sought. A practical scheme is developed which optimizes the step size at each iteration and retains the computational efficiency of layered models, resulting in a stable and rapidly convergent algorithm. The inversion of both magnetotelluric and Schlumberger sounding field data, and a joint magnetotelluric‐resistivity inversion, demonstrate the method and show it to have practical application.
03
1987
289
300
10.1190/1.1442303
10.1190/1.1442303
https://library.seg.org/doi/10.1190/1.1442303

https://library.seg.org/doi/pdf/10.1190/1.1442303

http://geophysics.geoscienceworld.org/cgi/doi/10.1190/1.1442303