May 2012

Issues Concerning Expressions Used in Tsunami Evacuation Alerts

Analyses Centering on Relevance Theory

Mitsuru Sugihara

It is pointed out that evacuation attempts did not work to the full extent in the Great East Japan Earthquake although there was a certain amount of time before the arrival of tsunami waves. Broadcasts urged local residents to evacuate using expressions such as “a six-meter high tsunami is expected” and “To those who are near the coast now, please evacuate to safe, higher ground immediately.” If these expressions did not work, what are the problems? The author discuss issues to be addressed in future studies on wordings in tsunami alerts by analyzing conventional, standard phrases used in tsunami warnings from a standpoint of the relevance theory to consider how listeners interpret sentences that senders of the information want to communicate.

In communications, listeners interpret the sentences they hear by assuming that these messages have relevance to themselves and making their own deduction according to the context. The level of relevance is proportional to the cognitive effect (impacts on their assumption) and is inversely proportional to the processing effort to interpret. Interpretation differs depending on the context on the listener’s end, and if the processing effort surpasses the cognitive effect, the deduction by the listener does not always match the intention of the sender. The messages carried in evacuation alerts sound clear, but there are sometimes certain elements that require a tremendous processing effort. The effort includes, for example, "disambiguation (removal of ambiguity)” from terms with various meanings such as ‘expected,’ ‘near,’ and ‘safe,’ “bridging inference” to relate the six-meter high tsunami to the necessity of evacuation such as sensing that ‘tsunami will break down the breakwater and destroy buildings,’ and “higher-level explicature” including the level of speaker’s certainty and sense of urgency regarding the height of tsunami and the necessity of evacuation. Broadcasting involves communications to the general public, in which it is impossible for the sender of information to fully understand the context of each listener. It is necessary for us to realize the limit in communication via broadcasts and explore expressions with higher explicitness that allow listeners understand the need to evacuate without doubt.

The NHK Monthly Report on Broadcast Research