New Zealand thrash metal band Alien Weaponry have just entered their second week at the top of the Spotify NZ Viral 50 Music Chart with their song Ru Ana Te Whenua.

Spotify is the world's largest online music distributor and it's 'Viral 50” chart measures not only streams and downloads of a song, but also its shares.

'It's a great way of measuring the buzz or excitement around a particular track,” says London based critic Hrefna Helgadóttir.

Alien Weaponry's song Ru Ana Te Whenua made headlines in its first week of release when it clocked up over half a million hits on Facebook in just 72 hours.

'We didn't expect this kind of reaction,” says singer Lewis de Jong.

'We were at a music industry thing and this guy comes up to me and says, ‘Congratulations you are number 2 on Spotify,' and I'm like, ‘What?! You're kidding, right?' Next day it was number one.”

It should be no surprise that people are excited and captivated by Ru Ana Te Whenua. The track, written entirely in Te Reo Maori, is dedicated to two of the band members' ancestor, Te Ahoaho, who fought and died at the historic battle of Pukehinahina (Gate Pa) in 1864.

It went viral on social media in its first week of release and has attracted attention from as far afield as Europe.

It's been a busy month for the teenage trio, who have also been nominated for the coveted APRA Silver Scroll award for their song Urutaa, and are currently in the middle of a national tour where they have been playing to sell-out audiences.

'We have a big summer planned too,” says bassist Ethan Trembath.

'What with finishing our album and playing some of the big summer festivals, it's going to be epic.”

Alien Weaponry will be on tour in New Zealand through August to October.