> Yet another to the improvement in the seismic sensors and technology used. This is a huge one. Almost all of that geoseismic downhole sensing technology use

> Yet another to the improvement in the seismic sensors and technology used. This is a huge one. Almost all of that geoseismic downhole sensing technology uses radioactive emissions. In 1940, it was impossible to "see" anything downhole with any reliability. Nowadays it's passe.