Thursday, July 23, 2015

Iceland May Be gearing Up For Another Round of Eruptions

Iceland may be gearing up for another round of volcanic and tectonic events, and some of them could be spectacular. The world only recently started paying close attention to Iceland's volcanoes after the eruption of Eyjafjallajökull in 2010, Grimsvötn the following year, and the recent eruption of a Bárðarbunga fissure system at Halhuraun. Bárðarbunga's eruption was the largest in recent history, with a massive lava field being issued, and millions of tons of SO2 gas.

The events at Bárðarbunga were part of the heart of what Iceland is, the eruptive center of a massive magma plume, which coincidentally lies on the spreading sealfoor rift of the North American and European plates. These plates are spreading, and recent seismicity shows just how active that spreading is.

Several volcanoes are either overdue for an eruption, or showing signs of awakening. Accoring to Jon Frimann of the Iceland Geology Blog, the island of Surtsey in the Vestmanneyjar volcanic system has shown signs of increased thermal activity. This is one system to watch, as in 1973, Eldfell volcano was born on the Icelandic island of Heimaey, with no warning. The eruption devastated residential homes, and advanced to the island's only port. During this eruption, Icelanders actually fought back the lava flow using massive pumps, piping cold ocean water in vast amounts onto the lava. They saved the harbor.

But this is a volcano, and it will erupt again in the future. The Island of Surtsey was created in a spectacular and never before documented eruption type. The term 'Surtseyan' eruption was born on the day Surtsey arrived. Boiling out of the ocean floor to breach the surface in 1963, the eruption lasted until 1967, building a new Icelandic volcano island. The island remains off-limits to all but the scientific community, who are studying biodiversity on newly created islands. 

This means that the people of Heimaey are living on a still very active volcano, and it has been quite silent for some time... until now. Unlike the recently erupted volcanoes that have been in the news, Vestmanneyjar is off people's radar these days, and unlike those volcanoes, does have population centers in its immediate vicinity. Heimaey after all is a very busy trading port.

Other volcanoes are stirring as well, some in the vicinity of the recently erupted Bárðarbunga system, which seem to have been disturbed by that eruption. Some have been eerily quiet for a long time, but are starting to have small quakes.

Hekla volcano is a dangerous volcano. Not because it is close to any population centers (although close enough for gas and ash to fall in the capitol), but because it is one of those volcanoes, like many in Iceland, which tends to erupt without warning. It has been experiencing sporadic quakes, which worry volcanologists. 

Torfajokull to Hekla's East, and NNW of Katla volcano, is also experiencing some quake activity, although this may be purely tectonic. This is a caldera system, which has not erupted in many centuries, however still has very active fumeroles, hot springs, and geysers.

Katla itself is assumed to be primed for an eruption, and may have had a very minor subglacial episode following the eruption of Ejyafjallajökull. It typically displays spurts of seismic activity, however would still be difficult to predict or monitor given its size, and the glacier mounted on top. This eruption would likely dwarf those of Ejyafjallajökull and Grimsvötn. But it just hasn't popped off as of yet. This would likely be the most dangerous eruption, as it would affect air travel (again) in Europe on a larger scale, create massive glacier outburst floods (jökullhlaups), and could last for a long time.

Tungnafellsjokull, to the East of the Bárðarbunga caldera, has been experiencing very unusual and heavy quake swarms during and after Bárðarbunga's fissure eruption and caldera collapse. I have stated in the past this may be a 'toothpaste tube' like scenario, where one magma chamber has stressed the other, and created a  more dynamic situation under Tungnafellsjokull. I still believe this to be the case. It is unknown whether this means an eruption will happen, or if things are settling down, but this volcano does not have a historical eruption record (in Iceland these date back to Viking times), so it could be unlikely... but nothing is impossible.

And to the North of Bárðarbunga, Askja volcano, which is another record-holding volcano in Iceland, had a catastrophic eruption in 1875, one of Iceland's largest, has been having persistent seismicity after the fissure eruption of Bárðarbunga. One of its much older and unmonitored neighbors, Herðubreið has followed that trend as well.

All of these volcanoes are in the vicinity of the spreading rift, and it does appear that the magma plume under Iceland is getting a little restless. Time will tell, but Iceland is an ever-changing landscape of ice and fire, and it does not appear to want to lose that description any time soon.

Tuesday, June 30, 2015

Hakoneyama Volcano In Japan Put On Alert [UPDATED 6-30-2015]

According to an article on The Asahi Shimbun, Hakoneyama (Hakone) Volcano in Japan has been put on alert, and visitors restricted from visiting the summit. Hakoneyama is the close neighbor to Mt. Fuji, which has according to experts been in a state of high pressure for some time now.

Hakoneyama has not erupted for some 2900 years, although the numerous hot springs, geysers, and fumeroles within the caldera point to an active magma system. Recent seismicity has given reason for the high alert status. According to the article, many shallow quakes have been recorded in the last month, with 16 quakes recorded on April 26th, and 72 from May 2-4.


Image from JMA detailing locations of quakes.


According to the article, inflation is being recorded at the volcano. While this does not point to an imminent eruption, this volcano was on the same large subduction zone that was affected by the infamous 9.0 quake of 2011, which caused the Fukushima nuclear disaster, a massive tsunami, and associated disasters. Quakes of that magnitude in active volcanic zones can produce some surprises.

Japan is likely more wary of volcanic unrest after Mount Ontake erupted with little warning, killing hikers and tourists, and stranding many in mountainside lodges. It was the worst volcanic disaster for Japan in recent times. The caution can and will save lives should the volcano erupt.

The Smithsonian GVP Characterizes the volcano as such:

"Hakoneyama volcano is truncated by two overlapping calderas, the largest of which is 10 x 11 km wide. The calderas were formed as a result of two major explosive eruptions about 180,000 and 49,000-60,000 years ago. Scenic Lake Ashi lies between the SW caldera wall and a half dozen post-caldera lava domes that were constructed along a SW-NE trend cutting through the center of the calderas. Dome growth occurred progressively to the south, and the largest and youngest of these, Kamiyama, forms the high point of Hakoneyama. The calderas are breached to the east by the Hayakawa canyon. A phreatic explosion about 3000 years ago was followed by collapse of the NW side of Kamiyama, damming the Hayakawa valley and creating Lake Ashi. The latest magmatic eruptive activity about 2900 years ago produced a pyroclastic flow and a lava dome in the explosion crater, although phreatic eruptions took place as recently as the 12-13th centuries CE. Seismic swarms have occurred during the 20th century. Lake Ashi, along with major thermal areas in the caldera, forms a popular resort area SW of Tokyo"

Since this is a breaking news story, and from Japan, it will be difficult to monitor the situation by normal means, but I'll keep an eye out, and should anything develop, I will update this post.

*****UPDATE 5/8/2015*****

Japan's Meteorologial Agency (JMA) raised the alert level of Hakoneyama to alert level RED. This is more than likely out of an abundance of caution, but after the eruption of Ontake, this is a prudent step. Volcanic tremor remains elevated, and steam vents are becoming more vigorous. If Hakoneyama were to erupt, it would be the first eruption in historical time.

****UPDATE 6/8/2015*****

JMA has lowered the alert level for Hakoneyama after visual observations noted a decrease in steaming from the various fumeroles and steam vents, in conjunction with a decrease in seismicity, as well as deflationary tilt. The alert level remains elevated, but no eruption now appears imminent.

*****UPDATE 6/30/2015*****
According to Reuters/Yahoo, Japan's Hakone (hakoneyama) volcano has now had a small ash-emitting eruption, after around a month or so of unrest. Japan had previously restricted access to the steam-vents area near the resort and issued an exclusion zone. The eruption was described as very small. 40 people were evacuated from the summit area. Live cams currently show vigorous steaming, suggesting that this was possibly a small phreatic (steam driven) eruption. New eruptions can happen at any time, and any new steam/hot rock interactions can cause more eruptions. Any fresh injection of magma (which is thought to have occurred) can increase this risk.

The volcano is now at Alert Level 3. A drone flight on June 20 revealed damage to facilities caused by large amounts of sulfur and gases being expelled by the volcano. 

Wednesday, June 17, 2015

Philippines' Mt. Bulusan Erupts

Two strong phreatic (steam-based) eruptions have occurred at Mt. Bulusan in Luzon, Philippines. It's last known eruption was in 2011. According to Filipino news sources, the first eruption lasted about 10 minutes, followed about 20 minutes later by a shorter eruption. There is currently no danger of magma injection or lava flow from the volcano.

Phreatic eruptions can occur without warning at many active volcanoes, especially 'wet' ones like volcanoes that have crater lakes at their summits, glaciers, or other sources of water. What occurrs is that water seeps into the volcano, making contat with extremely hot rock. This flashes the water into steam, causing a huge pressure buildup and subsequent rock explosion.

The reason there is no further danger of a larger eruption, is that typically phreatic eruptions are not related to new magma being injected. They are only related to surface water seeping into the hot, mostly solid rocks.

PHIVOLCS is updating the situation on Twitter, so you can follow the developments there. 

Tuesday, June 2, 2015

Northern Chilean Volcano Guallatiri Stirs

According to Volcanodiscovery.com and a few social media outlets, Volcan Guallatiri is experiencing a volcanic quake swarm, prompting SERNAGEOMIN to raise the alert level. According to the Smithsonian GVP, Guallatiri  has not had an eruption since December 2, 1960, and questionable activity was possibly observed in 1985.

So far this activity has not led to an eruption, but as is the case with many Ring of Fire volcanoes, that can change at any moment, and in Chile's case, with or without warning. Chile has seen a string of previously dormant, or long dormant volcanoes activate without warning. The 2008 eruption of Chaiten gave little to no warning. Calbuco volcano was also quiet up until it exploded.

The reason for this is the nature of the lava. Many of Chile's volcanoes are rhyolotic or andesitic, which make for a dense magma with tons of dissolved gases stuck inside waiting to burst, so these stratovolcanoes are particularly nasty when they choose to erupt.

If the volcano does erupt, I will update this post.

Thursday, May 28, 2015

Mt Shindake volcano on Kuchinoerabu Erupts

Hot on the heels of the eruption of Mt Ontake, Japan has had another eruption from one of its many active volcanoes. Mt Shindake volcano on Kuchinoerabu island erupted just hours ago, sending ash high into the sky and forcing evacuations. Unlike the previous eruption, nobody is thought to have been injured, and the island itself is not highly populated.

Shindake is a highly active volcano, having just erupted last year.

Japan has frequent eruptions from many of its hundreds of volcanoes. Japan and its outlying islands lay across the Pacific Ring of Fire, an arc of volcanoes that spans the Pacific tectonic plate, including Alaska and the West Coast of the US, down to the West Coast of South America. Japan's volcanoes, much like the ones that line the West Coast, and Alaska/Aleutian Islands, are composed of stratovolcanoes, which form due to subducting tectonic plates. Land dives under land, recycling sediments, and water into explosive magma, creating some of the most explosive volcanoes on earth.

Japan currently has several volcanoes either erupting or on high alert, or which have recently erupted. Sakura-jima (Aira), Nishinoshima (which started as an offshore eruption which later grew into a separate island, only to engulf its 'parent' and create a much larger land body), Ontake, and more have all erupted within the past year. Sakura-jima, Japan's most active in recent times, has frequent large explosions.

It is not known yet how long this current eruption will last, but it sounds like from the reports that it was a single explosion, and activity is not currently happening. This can change at any moment, so it is likely that the volcano will be heavily monitored in the next month or so.

I will update this post if anything further happens.