The scope of the project was expanded beyond the original notion of listening for low frequency electromagnetic signals.

Other potential precursor phenomena was identified, from the many possibilites discussed in the literature. 

There are any number of good choices, and the options are more in line with having too many possiblities, not scraping the bottom of the barrel for ideas.  Practically speaking, we will never put together enough time, people or resources to develop sensors and evaluate them all.

The idea of data transport via Amateur Radio was also added.  Otherwise, communications costs could eat up what are likely to be small budgets.  Additionally, the sensor sites are likely to be (optimally) located in remote areas, in or near fault zones, without benefit of land line service, or power.