Figure 14. Caldera, Chile marigram showing 1952 tsunami. 



The headquarters has rapid communications to a network of 

 reporting tide stations; the travel time to each tide station 

 from any nearby epicenter has been computed and is available 

 on a series of tsunami travel time charts. The tide obser- 

 vers are alerted to watch their tide records (usually re- 

 mot ed for safety and efficiency) at particular times and to 

 report the data from their records. If the tide records 

 confirm the existence of a tsunami, warnings including 



26-25 



