Considering its huge magnitude and its location in a densely populated area of Chile, the Maule seism of 27 February 2010 generated a low amount of victims. However, post-seismic tsunamis were particularly devastating on that day; surprisingly, no full alert was launched, not at the national, regional or local level. This earthquake and associated tsunamis are of interest in the context of natural hazards management as well as crisis management planning. Instead of focusing exclusively on the event itself, this article places emphasis on the process, systems and long-term approach that led the tsunami alert mechanism to be ineffectual. Notably, this perspective reveals interrelated forerunner signs of vulnerability.