The fall meeting of the American Geophysical Union (AGU) in San Francisco last month was bumped to the Moscone Center while the Civic Auditorium, its venue in past years, was being reinforced against earthquakes. And that may have been fitting, given the meeting’s focus on sudden events in Earth history : the first moments of fault rupture, repeated outbursts of icebergs during the last ice age, and a shift in the seasons in the middle of this century.