European and New Zealand geologists discovered near the Pacific island of Tonga underwater volcano with a very restless nature — its height varies by tens of centimeters in a few weeks, according to a paper published in the journal Nature Geoscience.
Submarine volcanoes on Earth is much more than "land" — 32,000 against 1.5 thousand — but they have been studied much worse because of their inaccessibility.
The underwater world of fire
A team led by Anthony Watts (Anthony Watts) from Oxford University (UK) has found most unusual volcano in the Pacific Ocean, near the Kermadec and Tonga archipelago, about 800 kilometers north-west of New Zealand.
In this area there are several chains of underwater volcanoes, in particular, a group of volcanic Manovay, which is especially the case unusual volcano.
This family was discovered by geologists in 1944. For 70 years, scientists have conducted several dives and noticed that his height greatly changed for 4-5 years, which took place between dimensions.
The study authors have taken to the area two expeditions in May and June 2011 on board the German research vessel Sonne. The shallow depth allowed geologists to conduct a detailed study of volcanoes.
Watts Group to follow the behavior of volcanoes, making daily heightmap Manovay volcanoes in the area during the time of expeditions.
The researchers then compared these maps with those obtained by other geologists in earlier studies in 2004 and 2007. It turned out that they were quite similar to each other — often highly collapsed areas and some lowland previous years was on the hill in 2011.
As you monitor the status of volcanoes, scientists surprised to notice that the height of the surface at some points of Manovay rose or fell right in front of them.
For example, two weeks between expeditions in May and early June 2011 the height of one of the volcanoes in some locations increased by 14 centimeters, while in others, it fell by 74 centimeters. In addition, during this time the volcano has had time to be a new crater, which grew on the site of failure, the discovery of the first expedition.
According to geologists, the volcano changes its height is about 10-50 times faster than the measurements indicated in previous expeditions. Moreover, growing and shrinking Manovay about a hundred times more potent than the most turbulent underwater volcanoes — "Kick-em-Jenny" in the Lesser Antilles arc in the Caribbean and Samoan volcano Vailulu'u.
However, the relatively constant size of the volcano indicate that it wakes up only for a few weeks a year. Believed Watts and his colleagues, the study of other underwater "Vesuvius" will help to understand whether this behavior is normal submarine volcanic centers or really unusual.