The lower floor of a school in the village of Sissano collapsed after being carried away 65 meters by tsunami waves. Photo Credit: Hugh Davies / NOAA NCEI
On an island north of Australia, on July 17, 1998, the country of Papua New Guinea suffered an earthquake of magnitude 7.0 on the Richter scale at 5:49 pm (local time). As a result of this event, three catastrophic tsunami were generated, which reached and devastated the entire villages of Warapu, Sissano, Malomo and Arop located on the north coast of the island, killing approximately 2,200 people, injuring 1,000, displacing more than 10,000 and counting 500 missing persons.
Hugh Davies relates in his book “Aitape Story: The Great New Guinea Tsunami of 1998” (2017) that after the first great impact of the earthquake, It was followed by several moderate and strong aftershocks that continued the rest of the night. These had damaged some structures and formed cracks in the ground. Next, says Davies, the villagers heard a loud roar and went to the beach to investigate the noise, coming to see how the sea was “bubbling” and “emptying the beach.”
In the distance, a large wave could be seen forming, to which the villagers began to flee, climb trees or climb structures as high as possible. The waves reached the majority of these villagers, reeling them vigorously and submerging them in the water, along with the debris that was carried away.
Later, it was confirmed that the tsunami had rise heights of up to 15 meters (49 feet) in the village of Arop and between 10 to 15 meters (39 to 49 feet) in an area 25 kilometers (15 miles) from the town from Sissano to Teles.
Descriptive model of the tsunami. Photo Credit: Eric Geist / USGS
Unlike many other tsunamis, this one aroused special interest within the scientific community since it was 10 minutes late than estimated after the earthquake. This led to the determination that this tsunami had been caused by an underwater landslide generated by the earthquake, of which there were no recent historical records that demonstrate the danger of tsunamis generated in this way.
In the same way as with other tsunamis before and after, the damage caused generated interest in many parts of the world regarding the consideration of the high risk that tsunamis can pose, especially those caused by underwater landslides.
The tsunami wave removed all traces of several hundred houses along the coastline of the Arop Villages. Photo Credit: Hugh Davies / NOAA NCEI
This generates a new variable in the formula of tsunami detection systems, taking into account not only the vibrations of the earth due to the movement of the tectonic plates, but also the underwater landslides. The importance of these continues to lie in keeping the population alert to any possible danger and minimizing the amount of losses.