Video update #4 - Lowering the Alert Level at Mt Ruapehu

At Mount Ruapehu since mid March, the level of tremor or type of volcanic earthquake, as well as the temperature of Te Wai ā-moe crater lake have been increasing. We've also seen increases in gas levels from the volcano. Correspondingly, we raised the volcanic alert level, to volcanic alert level two, which is the highest level before the volcano is in eruption, and it's consistent with moderate to heightened volcanic unrest.

Over the past week, volcanic activity has continued to increase, putting the unrest status firmly in the heightened unrest category. Volcanic tremor and volcanic gas have both continued to increase.

Carbon dioxide levels are at the second highest level that we've recorded since records began in the early 2000s.

The temperature of Te Wai ā-moe crater lake is now at 38 degrees Celsius. The sustained nature of the unrest of the volcano is different to the typical start of a heating cycle.

The level of gas and the level of tremor at the volcano at the moment indicate that magma could well be interacting with the geothermal system inside the volcano.

The most likely outcome of the current unrest episode at Ruapehu is that there will be no eruptive activity.

This is consistent with unrest over the last 15 years, which have also had no eruptive activity following them. There is the possibility of one or more eruptions impacting the summit area of Ruapehu, and also putting lahars into catchments, particularly the Whangaehu valley. This might be similar to the eruption of September 2007.

The chance of a larger eruption like some that occurred in 1995 to 1996 has increased, but remains very unlikely. That's the scale of eruption that might put out more widespread ash.

We expect an eruption of that scale would probably occur after a sequence of smaller events, mainly due to the presence of a crater lake.

It's important to remember that Ruapehu is an active volcano, and it can erupt at any time. with little or no warning.

The national emergency management agencies get ready website has information to help you understand what to do before, during and after a volcanic event.

As of today, the 13th of April, there was a two kilometer exclusion zone from the center of crater lake. But that could change.

It's important to look to the Department of Conservations website and social media pages. If you're planning on heading to Tongariro National Park to get the latest risk information and what to do.

We continue to monitor the volcano and conduct regular gas flights to understand what is happening. We will update the status of the volcano through volcanic activity bulletins, the geonet website and app.