7.2-magnitude earthquake strikes off Vanuatu, tsunami warning for coasts within 300 km

A very strong earthquake of magnitude 7.2 on the Richter scale struck near Vanuatu, an island nation in the South Pacific, on Saturday, October 24. The tremor shook the entire South Pacific region. The Pacific Tsunami Warning Center (PTWC) then issued a warning of dangerous tsunami waves for nearby coasts.

According to the United States Geological Survey (USGS), the epicentre was about 200 km west of Sola in the Vanuatu islands. It lay just 10 km below the sea. In geological terms, shallow earthquakes release more powerful energy and can cause a sudden, large change in sea water levels. For this reason, the quake is feared to have a very strong impact.

According to the USGS, a second earthquake of magnitude 6.9 was recorded in the same area a few seconds after the first. It struck about 197 km west-northwest of Port Olry. Scientists are closely examining whether these were two separate earthquakes or a difference in estimates of different phases of one large earthquake. Powerful tremors were also recorded one after another on the seabed after the main shock. In the past 30 days, 68 earthquakes have been recorded in the area, and this is the largest of them.

A few minutes after the quake, the Pacific Tsunami Warning Center issued an official warning. According to the centre, all coastal areas within 300 km of the epicentre could be hit by large and destructive waves. When such a strong jolt occurs at a shallow depth such as 10 km under the seabed, billions of litres of ocean water are suddenly displaced, and this produces tsunami waves.

The administration has put the islands and coastal villages around Vanuatu on high alert. People living near the shore have been ordered to move to safety and take precautions. Fishermen, tourists and residents on the coast have been told to take shelter immediately on high, safe ground. Rapid rises and falls in the water level are feared. There is considerable panic among local people.

Vanuatu is a country of small islands scattered across the South Pacific, and it lies in a highly sensitive geological belt of the world-famous Pacific Ring of Fire. The world's largest number of earthquakes and volcanic eruptions occur here. Tectonic plates inside the earth grind against each other or slide one under the other here, causing big earthquakes to occur repeatedly. Light and moderate tremors had also been recorded in Vanuatu a few days earlier. After today's 7.2 tremor and the tsunami warning, however, vigilance has been raised across the Pacific region. Waves formed on the seabed can travel at hundreds of kilometres an hour, so caution is very important in the first few hours.

Local administrations in Vanuatu and the surrounding islands have readied emergency arrangements. In some relief, no official report of major loss of life or property has come in during the first few hours. Even so, an assessment is under way of whether buildings have been damaged in settlements far from the epicentre. Experts say that however strong an earthquake is, its impact depends on distance from human settlements, the construction of buildings and the geography of the coast. For now, all international monitoring agencies are keeping a close watch by satellite on activity in the area and on the movement of sea water.