Nearly 1,500 years ago a massive flood in Geneva reportedly swept away everything in its path -- mills, houses, cattle, even entire churches. Now researchers believe they've found the unlikely sounding culprit: a tsunami-like killer wave in the Alps. The threat, they add, may still be very much alive. (Video: Tsunamis 101.) Spurred by a huge landslide, the medieval Lake Geneva "tsunami" (technically defined as a seismic ocean wave) swamped the city, which was already a trading hub, according to a new study. Far from any ocean, the massive wave was likely generated by a massive landslide into the Rhone...