[capybara]

what could case a low-frequency EM pulse that
1. was not audible like an explosion would be
2. caused a two-block power outage
3. stopped some cars dead in the street, but mainly older cars
(speculation: the newer cars have better shielded spark plug wires)
any guessses, links, or XPeriences as to what causes this?

(fwiw, this occurred last weekend in carlsbad, california
and our local power co., sdg+e, said it was a low-frequency
EM pulse)