While Chile races to deliver aid, Tsunami predictions miscalculated

As a result of the earthquake in Chile that occurred on Saturday, the Japan Meteorological Agency (JMA) issued major tsunami warnings for the first time in 17 years on Sunday morning.

Fortunately, the waves, which had been predicted to reach a height of three meters on the Sanriku coast, were smaller than expected and no casualties have been reported, but many residents living in coastal areas were forced to evacuate. What was the process leading up to the major tsunami warning, and did evacuations proceed smoothly?

“In addition to the tsunami’s energy turning out to be smaller than calculations we got from simulations, submarine topography and other factors weakened the concentration of energy more than we’d expected,” explains Yasuo Sekita, director of the JMA’s Earthquake and Tsunami Observations Division.

Rescuers searched for survivors Monday as crews sought to deliver food and water and prevent looting after the fifth strongest earthquake in 100 years ravaged central and southern Chile.

More than 1.5 million people were without power in and around the capital of Santiago, according to Chile’s National Emergency Office, but the hardest-hit areas were farther south, in the Maule and Bio Bio regions along the coast.

Authorities said 541 of the 708 reported deaths happened in Maule, where a sewer system collapsed, water towers were close to toppling and communities lacked basic services, the emergency office said.

Many people were without safe drinking water and electricity or gas service in Bio Bio, where 64 deaths occurred, according to the Chilean government’s latest figures.

Rescuers from Santiago, fresh from a stint in earthquake-ravaged Haiti, worked through the night to free people who could be trapped in a 15-story building in the hard-hit city of Concepcion in central coastal Chile, about 70 miles (115 kilometers) from the earthquake’s epicenter.

Firefighters said they believed they heard tapping from inside the building. Authorities said 40 or 50 people could be inside but do not know whether they are alive or dead.

The rescue and recovery work unfolded as Chile’s defense minister blamed its navy for not issuing a tsunami warning after the 8.8-magnitude earthquake rocked the South American country Saturday.

Such a forewarning could have allowed villagers on the coast to flee to higher ground.

“The truth even if it hurts is that a division of the Navy made a mistake,” Defense Minister Francisco Vidal said.

After the quake initially struck, President Michelle Bachelet said a tsunami was unlikely.

Yet a large wave crashed later into the Chilean islands of Juan Fernandez, killing at least eight people and leaving another eight missing, the Chilean emergency office said. Waves caused damage along the coast of the Chilean mainland as well.

Dozens of countries posted tsunami warnings, and Chilean authorities later realized the earthquake generated large waves that slammed coastal areas.

“What we saw between the sixth and the ninth region is a tsunami,” Vidal said.

The Navy has an emergency system under which captains in each port may issue warnings when sea levels begin to rise.

Those port captains were the ones who eventually sounded the alarm, warning residents to flee, and helped prevent additional loss of lives.

“There was a mistake,” Vidal said. “Fortunately, the system was activated.”

Tsunami prediction is affected by the topography of the ocean floor between the epicenter and Japan. However, in contrast to the seas close to Japan where research has been making progress, there are quite a few countries in the Pacific Ocean where such research is inadequate. In addition, compared to Japan, where seismographic networks exist throughout the country, there are more than a few countries that are also affected by earthquakes but do not have many seismographs, making it difficult to get the big picture. As such, while predictions in Japan are based on data of tsunami that hit Hawaii in combination with examples of past tsunami and other information, there is a tendency for the results to lack accuracy.