You said: 1)The frequency is said to range from 30 to 80 Hz (which I think are elf frequencies which were initially reported by Fraser-Smith as happening before Loma Prieta (?)).

No - that was Ultra Low Frequency - I believe its below 10Hz, maybe even below 6Hz - I've posted it here recently. As well as links to various ULF sites - on this page even (not in the archives yet)

Canie