1. A computer-implemented method for estimating a physical properties model in a subsurface region using data comprising two or more geophysical data types, said model comprising numbers in a model parameter domain representing one or more physical properties, said method comprising: using a computer to jointly invert the data in a plurality of sequential phases, wherein in each phase until a last phase, only a portion of the data is inverted in order to infer a subset of the model's parameter domain, said portion being determined at least partly based on relative frequency content of the two or more data types, wherein in a first phase of the sequential phases, the portion of the data inverted is longer wavelength data from the data's frequency domain, and model parameters expected to vary at shorter wavelengths are frozen, further comprising, between said first phase and said last phase, one or more intermediate phases, each intermediate phase and the last phase progressively using more of the data frequency domain and inferring more of the model parameter domain, and wherein a last of the plurality of sequential phases yields a final subsurface physical property model that provides reservoir properties for the subsurface region; and prospecting for hydrocarbons with the reservoir properties of final subsurface physical property model.