Hydrothermal activity is increasing at White Island which could be the start of an eruptive process, says GNS volcanologist Brad Scott.
The volcanologist visited the island volcano off the Bay of Plenty coast on Monday following reports of increased activity from tour operators, and a rise in activity showing on the island seismometer.


Increased hydrothermal activity in the White Island crater. Photo: Brad Scott, GNS Science.


“Unrest has increased and this could go one of two ways,” says Brad today.

“It could fizzle out and go away, or it could lead into the next eruption. It’s a 50:50 call either way at the moment.”

The activity is the strongest Brad has seen since the late 90s, which led to a large eruption in 2000, says Brad.
"The hydrothermal activity is some of the most vigorous I have seen at White Island for many years. This type of activity usually leads to stronger volcanic activity and is a significant concern.

"Increases in hydrothermal activity often lead to explosive eruptions and that can be quite dangerous for visitors."
The eruption on August 5, 2012 threw a few rocks out which could have affected people if they had been there, says Brad.
White Island is 49km north of Whakatane, and about 321 metres above sea level. Its full height is about 760 metres above the sea floor. The visible part of the submarine volcano is 2.4 km by 2km. It’s footprint on the seafloor is 14km by 16km.
It is New Zealand’s most active volcano, but its eruptions do not affect the mainland, says Brad.

Ash from the volcano has in the past been mistaken for pollen and goes unnoticed by most people.

The likelihood of the mainland being affected by an eruption through a tsunami would be minimal.

A tsunami study done by the University of Waikato found the wave that reached the Bay of Plenty beaches would be about knee high.

“They looked at the tsunami more so from the land slide risk,” says Brad.
“If there was an eruption induced land slide it clearly demonstrated there was no significant risk to the coast.”
 Brad says what he viewed yesterday is increased hydrothermal activity in the small ’hot lake’. Large amounts of sediment have surfaced and vivid white steam and gas was flashing from the base.

This sort of activity has been increasing since late 2012 and is now semi-continuous, says Scott.
The lava dome first noticed in late November has not changed since earlier this month.


http://www.sunlive.co.nz/news/37945-white-island-awakening.html

It seems quieter now at the White Is volcano.

Actually the unrest has increased, volcanic earthquakes are occurring

Volcanic Alert Bulletin WI-2013/3 - White Island Volcano
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24 January 2013, 4:00pm - Volcanic unrest increases, Aviation Colour Code changed to Orange.
Over the last 20-30 hours the style of seismic activity at White Island has changed. The level of volcanic tremor has started to decrease, but hybrid volcanic earthquakes have appeared. Hybrid earthquakes are typically associated with the movement of molten material (magma) within an active volcano. This change in activity is consistent with an  increase in the level of unrest; hence the Aviation Colour Code has been lifted to Orange.

The current episode of activity started in August 2012 (explosions and ash emission) followed in November 2012 by extrusion of a small lava dome. Elevated but not high unrest followed. However, volcanic unrest has been increasing at White Island since about January 14. This unrest has been manifested as increased hydrothermal activity in the ‘hot lake’ and has been described as some of the most vigorous activity seen at White Island for many years.

GNS volcanologist Gill Jolly commented “Visitors to White Island are now at the highest level of risk since the start of the 2012 eruptions. Hazards to visitors can include the health effects of volcanic gas exposure, including respiratory issues, skin and eye sensitivity to acid gases. Explosive eruptions can occur at any time with little or no warning. We advise a high level of caution should be taken, if visiting the island”.

The outcomes of the unrest could be either the passive intrusion of magma to shallow depths with no changes in surface activity, more dome building as in November 2012 or explosive eruptions and ash emissions, like in August 2012.

The state of unrest at White Island is increasing and future eruptions are possible with little or no warning. The increased level of unrest does mean that there is an increased hazard to visitors. GNS Science continues to closely monitor White Island through the GeoNet project.

Weather permitting a ‘gas flight’ will be made tomorrow morning to ascertain if there have been any changes in the gas flux from the volcano.

Background
Hybrid volcanic earthquakes are so called because they are a mix of rock fracturing and magmatic vibration. They are thought to represent the movement of magma in a volcano.

Aviation Colour Codes are based on four colours and are intended for quick reference only in the international civil aviation community.

The Volcanic Alert Level ranges from 0 to 5 and defines the current status at a volcano. Level 1 indicates signs of volcanic unrest.

The GeoNet project is funded by EQC and provides monitoring for all of New Zealand’s volcanoes.

 

Brad Scott

Duty Volcanologist

Yes, I counted 25 on the drum at one stage late yesterday

Up to 17 in the last 24 hours again

Guilty I am! 
I count 21 volcanic quakes in the past 24 hours

The volcanic tremours have definitely gone quiet for a while now - well quieter and quieter.  It stopped very suddenly too. After five more days or so, they will probably lift the aviation restriction, but they will do some gas tests first in the air above the volcano to check for types and levels of gases before they make their decision.

Nice one David.
Very dry vent.

Starting to get noisy again, the Te Kaha drum is also noisy...  may not relate but there are not quake spikes at the same times  - bar a couple.