Alameda is a free 1-D MT inversion runs under Windows OS (xp, vista 32bit, vista 64bit). This free software is designed to invert MT data, e.g apparent resistivity as a function of period. The software is very handy, since the size is only 800kb. It contains five user friendly tabs, and each tab contains useful tool for 1-D MT study. The first panel, for example, is shown in the two figures below. The blue dots are the observed data, while the red dots are the theoretical response. The model is a multi-layered earth, as shown by this screen shot. Spurious data points can be masked out to yield the expected geological image. And to regularize the inversions, the initial model, the minimum, and the maximum resistivity of the model can also be assigned prior to the inversion, as shown by this screen shot.