Forty countries lying along the Pacific Ocean from Asia to the Americas are putting their tsunami early warning systems and escape drills to the test this week, with the key message for some coastal communities being "run and seek higher ground".
Loudspeakers, sirens and signs marking evacuation routes are being used in tsunami simulation exercises in countries including Colombia, Costa Rica and Nicaragua, to ensure warnings reach at-risk coastal communities and get them to safety.
The United Nations-backed initiative aims to test communication systems used in earthquake and tsunami warnings and improve how countries prepare and respond to disasters.
Nearly 75 percent of deadly tsunamis occur in the Pacific Ocean and connected seas, according to the U.N., causing thousands of deaths and high economic losses.
National emergency response centers and agencies in 40 countries can choose one of six simulation exercises involving earthquakes off the shores of Japan, Tonga, the Philippines, Chile, Peru, Colombia and Ecuador.
Countries participating in the five-day drill that wraps up on Friday span from Thailand, China and Australia, to the Pacific Islands, the United States and south through to Chile.
They will receive messages from the Pacific Tsunami Warning Center in Hawaii and Japan's Northwest Pacific Tsunami Advisory Center.
"This exercise will be testing a new enhanced data product that will allow governments to better forecast a tsunami's height, energy and direction of waves, and then use that data to communicate with local populations," said Bernardo Aliaga, head of UNESCO's Intergovernmental Oceanographic Commission Tsunami Progamme.
It is hoped such simulation exercises will allow countries to better assess the threat posed by a tsunami or other natural disasters and determine the appropriate level of alerts to be issued.
"We know the frequency and intensity of some kind of extreme weather-related events have been increasing in recent years. Governments and communities need to prepare for such events at anytime," Aliaga told the Thomson Reuters Foundation in a telephone interview from Paris.
Such UNESCO-led tsunami simulation exercises in the Pacific have been held four times in the past decade.
As a result, national emergency response centers are now better equipped, and there is greater awareness among government officials about disaster preparedness, Aliaga said.
But ensuring that tsunami early warnings get through effectively to those living in remote coastal areas and that people know how to keep safe from the deadly waves, which can reach heights of 10 meters (32 feet) or more, remains a key issue.
"The most challenging aspect is to reach the most vulnerable people living in isolated villages that aren't well-connected with the information coming from the national government," Aliaga said.
He added that awareness also needs to be raised among at-risk coastal communities about how to spot an imminent tsunami through signs such as receding waves.
Another ongoing challenge is to improve coordination and communication between the various government agencies involved in issuing tsunami alerts, a problem exposed following Chile's 2010 deadly earthquake.
"The exercise is about developing standard operating procedures on what each chain of the emergency response has to do and is responsible for," Aliaga said.
Countries participating in the tsunami drill will meet in Hawaii in April to review their disaster response.