WHAM: Web Hosted Active-source Modeling

This page provides access to interactive online dipole-dipole marine EM modeling. At this time it is limited to one-dimensional (1D) experimental design, but as long as the transmitter and receiver are both over the target body, 1D modeling is sufficient to choose an appropriate transmitter frequency and estimate maximum target response as a function of source-receiver offset. The modeling engine uses the code of Flosadottir and Constable (JGR, vol 101, page 5507), which is based on the algorithm of Chave and Cox (JGR, vol 87, page 5327).

Two plots are generated; one for the radial mode (transmitter and receiver colinear) and one for the azimuthal mode (transmitter and receiver parallel). In each case the transmitter is 100 m above the seafloor and the receiver on the seafloor. On each plot are four curves:

• i) The response of the model input by the user.
• ii) The response of a half-space having the same conductivity as the top layer. This will often be the response of the model without the target horizon, and will provide a visual indication of the target response.
• iii) The response of the air wave only. This is generated by a heuristic algorithm and serves only to indicate which parts of the model and half-space responses are propagated through the air.
• iv) The noise floor of the SIO transmitter-receiver system. This serves to indicate what parts of the model curves are measurable in practice.

This work has been made possible by the Seafloor Electromagnetic Methods Consortium . As is normal practice, the addresses of people accessing this site are monitored by our webserver. However, the input models are not monitored or stored.

RUN MODEL