Quakes in American Samoa likely to be linked to volcanic activity

The authorities in American Samoa remain on alert due to extensive underwater volcano activities.

The US Geological Survey said earthquakes have been felt over the past few days and they are ongoing.

The agency said the quakes may be caused by a volcano, but a large eruption like the Hunga Tonga Hunga Ha'apai in January is extremely unlikely.

The territory's Emergency Operations Centre was activated in response to reports from residents of Ta'u and Ofu islands in the Manu'a group of the grounds shaking.

The first shakes were reported at 3pm local time on Tuesday with the last reports at 11pm that day.

Residents on Ofu said they saw the ocean recede and bells were rung to alert residents.

Manua representative Tiaoalii Sai, who is in Hawaii, said he was told by his brother-in-law in Ofu that people started moving towards the road leading up to the mountains after the bells were rung.

He said some people ignored the instructions saying faith in God will protect them.

Sai said several hours later people returned to their homes after checking with Homeland security that it was safe to do so.

The shaking centres on Vailulu'u, an unpredictable and very active underwater volcano located between Ta'u and Rose Atoll.

Ta'u Emergency Operations Centre official Tupuola Lualemaga said they haven't experienced any more tremors since the initial shaking.

"We received some calls yesterday but last night we didn't receive any calls, we did not evacuate anybody because ... received a warning call from the homeland security ... and we take action but we did not evacuate."

Mapping the volcanic area

In early 2017 an American Samoa Expedition of NOAA: Suesuega o le Moana o Amerika Samoa, explored Vailulu'u seamount, and discovered an active volcano lying in the eastern region of the Samoan hotspot.

The last visual survey of the volcano took place in 2005, but the seamount had been mapped since.

Reports from the NOAA website say comparison of multibeam data collected in 2012 with new bathymetric data collected during this 2017 expedition, showed that the volcanic cone in the crater, called Nafanua, had grown substantially since the seamount was last mapped in 2012, having formed two distinct volcanic features.

This volcano in the Samoa Islands rises to a height of 5km from the sea floor. It is located to the east of Tau Island and it is said to have emitted smoggy water from its peak recently.