On Wednesday evening, a powerful earthquake struck the Indian Ocean southwest of the Indonesian island of Sumatra. There were post-warnings of a possible tsunami, according to officials. However, the warnings were lifted as there were no signs of a tsunami detected off the coast of Sumatra.
According to said Sutopo Purwo, a spokesman for the National Disaster Mitigation Agency, tsunami warnings are based on modeling, while tsunami buoys in Indonesian waters haven’t reported any existence of the phenomenon.
“Many buoys are broken and not functioning, so we don’t know whether the potential for a tsunami in the waters is true or not,” he added.
The earthquake had a magnitude of 7.8, which is high enough to cause severe damage, yet no damage or causalities were reported, said a spokesman for the Disaster Mitigation Agency. The reason the earthquake struck in a more quiet way was due to the location of the tremor was centered under the ocean at 659 kilometers from the town of Muara Siberut.
While the quake’s epicenter hit far from the Mentawai Islands, a small island chain southwest of the country’s main island of Sumatra.
The already lifted tsunami warning, however, sent panicked residents rushing from their homes, as the region is known to have dealt with quakes in the past. While the tremors were first noted in the capital Jakarta on Java Island as the people saw tall buildings shake, West Sumatran town residents confirmed the quake was lightly felt.
Lessons from the past
As a result of previous earthquakes’ damage and causalities to Indonesian main island Sumatra, plans for evacuation have not been improved properly, as well as a lack of improvement for the island’s roads to provide better escape routes from tsunamis.
It’s important to differentiate the consequences of a shallow undersea quake like the one occurred on Wednesday and the tsunami that may be generated from the undersea quakes.
For instance, on December 26, 2004, a 9.15 magnitude quake opened a fault line deep beneath the ocean, triggering a wave reaching up to 18 meters high. So even if the quake’s magnitude were high, the massive impact that could generate by creating a gigantic wave would depend on its location.
It’s important to remember that tsunamis are caused by massive displacements of seawater when a powerful earthquake lifts the ocean floor. As the world’s largest archipelago, Indonesia is prone to seismic activity because of its dangerous location on the Pacific “Ring of Fire”. The ring consists of an arc of volcanoes and fault lines circling the Pacific.
Source: NBC News