Back in August, an enormous floating mass of pumice was spotted in the South Pacific Ocean off the coast of New Zealand. New evidence of changes on the seafloor confirms an erupting undersea volcano created the sprawling rock raft.

New Zealand scientists aboard the research vessel Tangaroa recently mapped the underwater volcano, Havre Seamount, which erupted on July 19 and was thought to have sent pumice rocks floating over a stretch of ocean 8,500 square miles (22,000 square kilometers). Now, the scientists say they detected a new volcanic cone - a feature built during an eruption - at Havre Seamount, reaching within 3,600 feet (1,100 meters) of the surface.

(Pumice forms when volcanic lava cools quickly. Gas gets trapped inside as the lava hardens, resulting in porous lightweight rocks that can float.)

A Japanese scientist has warned Mount Fuji is due for a "big-scale explosive eruption" that could affect millions of people and cause billions of dollars worth of damage.

Last month a study found the magma chamber under the mountain has come under immense pressure, which could even trigger a volcanic eruption.

It said the added pressure could have been caused by last year's earthquake, which was followed a few days later by another large tremor directly underneath Fuji.

Professor Toshitsugu Fujii, the head of Japan's volcanic eruption prediction panel, says an eruption could cause chaos and carnage all the way to Tokyo.

"Mount Fuji has been resting for 300 years now, and this is abnormal," he told Saturday AM.

"It usually erupts in some form every 30 years.

"So the next eruption could be a big-scale explosive eruption."

One of Indonesia's most active volcanoes has erupted again, spewing clouds of ash, an official has said. The 1580 metre (5,214 feet) Mount Lokon on northeast Sulawesi island erupted at 2pm local time on Sunday with thunderous sounds heard as far as five kilometres away. "Lokon has been quite active the past few months. This was the seventh biggest eruption since mid-September," government vulcanologist Farid Bina told AFP from the volcano's monitoring post in North Sulawesi province.

Heard Island on the Kerguelen Plateau in the southern Indian Ocean consists primarily of the emergent portion of two volcanic structures. The large glacier-covered composite basaltic-to-trachytic cone of Big Ben comprises most of the island, and the smaller Mt. Dixon volcano lies at the NW tip of the island across a narrow isthmus. Little is known about the structure of Big Ben volcano because of its extensive ice cover. The historically active Mawson Peak forms the island's 2745-m high point and lies within a 5-6 km wide caldera breached to the SW side of Big Ben.

A very hazardous volcano at the border of China and North Korea is growing more active, and might erupt in the next few decades, researchers studying the area say.

About 1,100 years ago, the Changbaishan volcano in northeastern China erupted, shooting superheated flows of ash and gas up to 30 miles (50 kilometers) away and blasting a 3-mile-wide (5 km) chunk off the tip of the volcano. The explosion, known as the Millennium eruption because it occurred close to the turn of the first millennium, was one of the largest volcanic events in the last 2,000 years.

Since the Millennium eruption, Changbaishan has seen three smaller eruptions, the most recent of which took place in 1903. Starting in 1999, driven by signs of resumed activity, scientists established the Changbaishan Volcano Observatory.

Now, data collected over the past 12 years suggest that changes in seismic activity, ground deformation and gas emissions all spiked during a brief period of heightened activity from 2002 to 2006. This suggests the magma chamber beneath Changbaishan has awakened, researchers studying the volcano say.

The researchers saw the number of earthquakes increase dramatically during this burst of activity. From 1999 to 2002, and from 2006 to 2011, researchers detected seven earthquakes per month. However, from 2002 to 2006, this rate increased to 72 earthquakes per month, peaking in November 2003, which saw 243 events. Most of these quakes are tied to a region 3 miles beneath the volcanic crater that has risen slowly over the years, which suggests magma is creeping upward.

A volcano has erupted on Indonesia's Sumatra island, spewing thick grey smoke up to 1.5 kilometres into the sky.

Monitoring official Suparno says Mount Marapi's eruption on Wednesday is its strongest since August last year, when its status was raised to level three out of four.

Roughly 1,100 years ago, the Changbaishan volcano that lies along the border between northeastern China and North Korea erupted, sending pyroclastic flows dozens of kilometers and blasting a 5-kilometer (3-mile) wide chunk off of the tip of the stratovolcano. The eruption, known as the Millennium eruption because of its proximity to the turn of the first millennium, was one of the largest volcanic events in the Common Era. In the subsequent period, there have been three smaller eruptions, the most recent of which took place in 1903.

Starting in 1999, spurred by signs of resumed activity, scientists established the Changbaishan Volcano Observatory, a network to track changing gas compositions, seismic activity, and ground deformation. Reporting on the data collected over the past 12 years, Xu et al. find that these volcanic indices each leapt during a period of heightened activity from 2002 to 2006.

The authors find that during this brief active period, earthquake occurrences increased dramatically. From 1999 to 2002, and from 2006 to 2011, they registered 7 earthquakes per month using 11 seismometers. From 2002 to 2006, this rate increased to 72 earthquakes per month, peaking in November 2003 with 243 events. Further, tracking the source of the earthquakes, the authors tie the bulk of the events to a region located 5 kilometers (3 miles) beneath the volcanic caldera, a source that slowly crept upward throughout the study period, suggestive of an ongoing magmatic intrusion. Gas composition measurements collected from hot springs near the volcano showed spikes in carbon dioxide, hydrogen, helium, and nitrogen gases, which the authors suggest could be related to magmatic outgassing. Ground deformation studies, too, show a brief period of rapid expansion.

Arif Huseynov: "The Volcano was too powerful at the beginning and the mud covered more than 2 ha of the area"

Baku. Kamala Guliyeva - Lokbatan mud volcano erupted in the morning has weakened, Executive of Mud Volcanism Department under the Geology Institute of the Azerbaijan National Academy of Sciences Arif Huseynov told APA.

Huseynov said that the eruption process is being studied. The volcano accompanied by a rumble at 05.00 spew flames at 09.00: "According to the preliminary observations, the eruption was powerful and mud spread across the area of more than 2 ha. The exact information will be announced after the measurements. But this eruption was more powerful than the eruption in 2010. At that time, the mud covered about 2 ha area."

Husyenov says that no flame is being observed in the area: "The volcano has already weakened. It is not likely to flame again, as it's weakened."

Volcanic activity on Spain's El Hierro Island has resumed far below the Earth's surface in a similar manner to last July, albeit slightly stronger, the director of the National Geographic Institute, or IGN, in the Canary Islands, Maria Jose Blanco, told Efe on Sunday. Blanco said that a peak of seismic activity is under way, a continuation of the volcanic process - a shifting of magma many kilometers (miles) underground - that began in July 2011 which, although the main activity ended at the time with an undersea eruption, that did not mean that the overall activity had come to a definitive conclusion.

The IGN official said that at present it is not expected that the seismic movements that have been registered - which have occurred at depths of some 20 kilometers (about 12.5 miles) - exceed 3.2 on the Richter scale, a fairly low level. Blanco could not specify how long this new round of activity would last, although she did say that seismic peaks like the current one would, in all likelihood, continue to occur. Therefore, she said, the IGN is studying the idea of convening the scientific committee of the Civil Protection Plan for Volcanic Risk in the Canaries after this reactivation in the depths of the El Hierro volcano, where over the past three days more than 330 minor seismic movements have been registered.