Volcano activity of August 2, 2012 - White Island volcano, New Zealand aviation code changed to Yellow

This (almost) daily post intends to follow up the activity changes of volcanoes all over the world.
This post is written by geologist Richard Wilson who specializes in Volcano seismicity and Armand Vervaeck. Please feel free to tell us about new or changed activity if we haven't written about it. -

August 2, 2012 volcano activity

Crater Lake at White Island has recently started to re-fill and gases are now vigorously streaming through it. Airborne gas measurements made yesterday show that the discharge of some sulphur gases has increased. During the past few weeks there has also been some minor volcanic tremor.
During 2011 and early 2012 White Island Crater Lake slowly evaporated to expose steam vents and form two large muddy pools. However, sometime between Friday July 27 and Saturday July 28, the lake level rose quickly by about 3 m to 5 m. Vigorous flow of gas and steam through the new lake can be seen from the air. Two photos at the end of this bulletin, taken from a similar position, clearly show the change in water level.

The lake has been inaccessible for many months and we have not been able to measure changes in its temperature or chemistry. Sulphur gases measured yesterday in the steam and gas plume have increased during the last three months but CO2 gas output remains at about the same level.
Since early July there have been intermittent periods of volcanic tremor, including several hours early on Saturday July 28 and during Monday and Tuesday this week. Tremor is not uncommon at White Island but earlier this year it had been at very low levels.
A recent ground survey showed that the main crater floor is no longer subsiding and now may be slowly rising.
These phenomena are typical for White Island’s activity, but are the first substantial changes to occur in the last few years.
White Island is an active volcano and there is always risk when visiting the island. Eruptions can occur at any time with little or no warning. The recent changes in activity suggest that the hydrothermal system has become unstable, and as a result the risk has increased. We advise extra caution should be taken, especially if approaching the Crater Lake and other active thermal features.
GNS Science volcanologists are monitoring the activity and further information will be released as soon as it is available.
The increased activity at White Island has no connection with the recent earthquakes and changes in gas flux at Tongariro volcano.
Alert Level remains at 1; Aviation Colour Code changed to Yellow
Image and text courtesy GEONET New Zealand and GNS Science

Activity observed by satellites
VAAC Darwin reports ash clouds up to 7000 ft (2.1 km) above Batu Tara volcano, lesser Sunda islands, Indonesia
No new explosion reports of Sakurajima volcano in Japan (thats news too 🙂 ). Thats all from the VAAC's today.
SO2 satellite images are revealing for 2 days in a row higher concentrations in the direct vicinity of Ijen volcano (on the map below check the cloud at Raung volcano, Java, but we think the SO2 cloud is coming from Ijen volcano who was reported to be more active the last couple of days.
Hard to say and almost impossible to be confirmed, but as Mount Pagan volcano (Mariana Islands) had an ash cloud eruption a few weeks ago, we think the the NOAA's satellite picture shows a new cloud today.
An SO2 cloud can also be seen to the east of Karymsky volcano, although it will be difficult to be confirmed as there are many volcanoes active on the Kamchatka peninsula.
Ambrym volcano, Vanuatu, active for quite some time, showed increased activity as can be seen on the satellite SO2 image.

Interesting articles
Hawaii Volcanoes National Park Turns 96
Today, Hawai‘i Volcanoes National Park turns 96 years old, and the park’s Centennial Anniversary is just four years away. Hawai‘i Volcanoes was the 15th park to join the National Park Service, which now has 397 national parks – including a total of eight in Hawai‘i. Established on Aug. 1, 1916, the same year as the National Park Service itself was founded, Hawai‘i National Park, as it was called then, also comprised Haleakalā National Park on Maui. In 1961, Haleakalā became its own separate national park. Read more ....
Article from the Hawaii reporter