AGU Chapman Conference on Giant Earthquakes and Their Tsunamis; Via del Mar and Valparaso, Chile, 16-20 May 2010 ; An AGU Chapman Conference commemorated the fiftieth anniversary of the 1960 M 9.5 Chile earthquake. Participants reexamined this earthquake, the largest ever recorded instrumentally, and compared it with Chile's February 2010 M 8.8 earthquake. They also addressed the giant earthquake potential of subduction zones worldwide and strategies for reducing losses due to tsunamis. The conference drew 96 participants from 18 countries, and it reached out to public audiences in Chile. Its program and abstracts are posted at http://www.agu.org/meetings/chapman/2010/acall/pdf/ Scientific-Program.pdf.