BBCnews is carrying this article on what looks to be two events caused by "strange" quarks hitting the earth. Subatomic particles dense enough and fast enough to cause seismometers to register them all over the planet is kinda scary actually. From the article:

One event occurred on 22 October 1993, when, according to the researchers, something entered the Earth off Antarctica and left it south of India 0.73 of a second later.