Island of Fogo Is Having Volcanic Tremor

The island of Fogo looks like something out of a sci fi fantasy movie. A massive island inlayed by a large caldera, with a spire-like volcanic cone in the center that looms high over the tropical landscape. Below the peak of Fogo (Pico do Fogo) lies a paved over, barren landscape, surprisingly home to houses and facilities built atop fresh lava flows. Fogo was one of the first volcanoes that fascinated me, given its striking appearance and remote location. To visit this volcano, for me, would be quite a sight.

Fogo is not a very well-known volcano, but it is capable of some serious eruptions. Indeed the original caldera forming event likely created tsunamis and landslides that would have hit the neighboring islands, and maybe even the African West Coast. The island itself is dotted with cinder cones young and old on its flanks, suggesting a very active life cycle as a volcano. Now, the volcano is getting seismic equipment installed on it, and already, results are coming in pointing to volcanic tremor, and small volcanic earthquakes. Fogo is waking up.  (or was it ever truly asleep?).

Fogo's last eruption occurred in 1995, when a small cinder cone was erupted on the WSW flank of the Fogo peak. This eruption started off as a fissure, and gradually built a cone, and produced slow moving pahoehoe lava flows that pooled at the base of the mountain.

Picture of the 1995 eruption of Fogo, from Smithsonian Global Volcanism Program website. Photo by Dick Moore, 1995 (U.S. Geological Survey)

The Smithsonian GVP Characterizes Fogo here:

"The massive 9-km-wide, horseshoe-shaped Cha caldera truncates the summit of Fogo stratovolcano, the most prominent in the Cape Verde islands. An ash plume (center) rises from the western flank of a steep-sided central cone, Pico, that rises more than 1 km above the caldera floor to form the 2829 m high point of the island. Pico, which is capped by a 500-m-wide, 150-m-deep summit crater, was apparently in almost continuous activity from the time of Portuguese settlement in 1500 AD until about 1760."

An eruption of Fogo today would likely be characterized by another small cinder cone building event, or possibly a larger more explosive event from the summit cone (which has not recently erupted historically speaking), which could be capable of strombolian type, or Hawaiian type eruptions. Flank eruptions on the West side of Fogo were considered to be Holocene, but most eruptions have occurred on the East side of the caldera rim recently. The West side of the island is heavily vegetated and is probably not at risk.

The Portuguese islands of the Cape Verde chain are all volcanoes, or have been volcanoes at one point in time or another (some are very old). Installation of more monitoring equipment is exciting news for some of us who long for a global volcanic monitoring network, and certainly for the scientists who will be poring over reams of seismic data. Every year, volcano monitoring gets better and better, and disasters and deaths are able to be more easily averted due to good early warning systems. It is my thought that within 10-20 years of today, we will actually be able to routinely scan a volcanoes magma reserves to determine whether an eruption is imminent, and when it might occur. The new muon-based mapping technology developed in Japan is a major step forward, and is currently being tested on volcanoes such as Vesuvius, and Fuji. 

If anything new develops on Fogo, you'll read about it here!

Is Geothermal Drilling A Potential Hazard?

News has recently surfaced that a 5.2 earthquake in the heart of Oklahoma was caused by drilling of waste water disposal wells that went some 1.5 miles underground. This apparently resulted in underwater channels opening up, cracks in the rock, and eventually slippage of an old fault line that had some tension but was rather stable before the water lubed up the fractures and produced a large earthquake. This and other stories have been made apparent lately, and with the USGS real-time plugin for Google Earth, you can easily tell that some areas doing deep drilling, hydrofracking, and geothermal prospecting do in fact affect seismicity in the areas that they are produced.

One such area that has a long history of this is Clear Lake/Geysers geothermal field in Northern California. This is one of the worlds largest producing geothermal operations, with more than 20 separate drill holes and facilities dotting the SW rim of the active volcano (it has not erupted in thousands of years, however hot springs, fumeroles, and seismicity indicate the presence of a large silicic magma chamber probably consisting of 'crystal mush'), the area is regularly host to about 20 small tremors in any given week, sometimes up to magnitude 4.0.

Other geothermal areas like Hengill in Iceland experience regular quake swarms as a result of geothermal prospecting.

The evidence for human meddling with fault lines goes back even as far as WWII, when a secret base in Hawaii called "Red Hill" was being constructed, engineers determined that dump trucks and other waste management vehicles would defeat the purpose of a hidden, underground base. So they did what they thought at the time was logical. Drill a gigantic, 1.4mi hole into the earth to dispose of waste products and be done with it. This ended up interacting with hot rock, and lubricating rock fractures, and before they knew it, they were getting many tremors per day, and were (disgustingly) forced to pump out thousands and thousands of gallons of polluted water to stop the quakes. Pretty nasty.

Today, with drilling 'en vogue' in the United States thanks to energy requirements, hydrofracking, waste water drilling, and geothermal prospecting are common nation wide. While industries would love to deny the facts, the facts can speak for themselves. Drilling massive holes in the earth, and pumping liquids into them, will affect the stability of the crust. Plain and simple. While most drilling produces seismicity that nobody notices (1.0 mag-3.0 mag quakes are barely able to be felt), sometimes, such as the 5.2 quake in Oklahoma, the quakes can be damaging and dangerous.

This will not stop industry from drilling these holes. The money is too good, and some of the resources are rare. But understanding the process might make one reconsider living around such a project, or at least, take the mystery and fear away as to "why are earthquakes happening in Oklahoma??". Human activity does affect our planet. It alters our forests, flora, fauna, and our geology. We can level mountains with reckless abandon, and mine our earth for precious and useful minerals... but we are only now realizing how much this can affect the earth's crust. 

Mexico Raises Popocatepetl Alert Level

One of Mexico's most active volcanoes, Popocatepetl (Smoking Mountain) is showing signs of increased unrest, prompting the local government to raise the alert level to 3 (out of a max of 4), and instituting an exclusion zone of up to 7 miles from the summit. After 40 minutes of volcanic tremor, and some minor exhalations of ash and steam, the volcanoes activity has been steadily increasing over the past couple of days. Popocatepetl's last major eruption in 2000 caused widespread ashfall, but no fatalities.

The volcano, easily seen from Mexico City, is one of Mexico's tallest volcanoes, reaching heights of 17,802 feet at the summit (this does vary as lava domes are made, collapse, and the volcano swells or subsides). It has a long history of explosive eruptions, some of which were plinian in nature (shooting high volumes of ash, lava, and gas high into the atmosphere). The last plinian eruption occurred somewhere around 800AD. The volcano lately has only had short bursts of ash and steam.

The reason for raising the alert level is the amount of time the tremor was sustained. A 40 minute long intense volcanic tremor that was heard and felt by locals means a swift injection of magma into the chamber has probably occurred. This could indicate that "Popo" is gearing up for a large eruption, probably on the scale of its 2000 show. It is still too early to tell if Popo will put on a major eruptive display, or if it will sit and seethe. Incandescence was observed at the summit crater overnight, indicating either a building lava dome, or lava effusion at the summit. This is actually typical of the volcano, which doesn't go long between eruptive episodes, minor or major.

Mexico has suffered several large quakes in the last month, which leads to speculation about the effects of earthquakes on volcanic systems. While the quakes were large, they were actually hundreds of miles away from the actual volcano, so earthquakes affecting this volcanic system from that distance is pretty unlikely.... not impossible, but very unlikely.

Cascades Volcanoes, Sleeping Giants

The entire West Coast of the United States, and Canada are strewn with large stratovolcanoes. From Mt. Shasta, to Mt. St Helens, to Rainier, to Glacier Peak, the West Coast is literally pockmarked with large, explosive, and potentially dangerous volcanoes. The Cascades Volcano Observatory (CVO), and the newly minted California Volcano Observatory (CalVO), are tasked with monitoring these massive volcanoes that are near heavily populated centers. With so many volcanoes on the West Coast, it is a wonder that not a lot of people out here actually realize how volcanically active California, Oregon, and Washington actually are.

The last eruption of a Cascades range volcano was in May 1980 (actually I need to correct this... Mt St Helens erupted from 2006-2009 with a lava dome building event!), when Mt St Helens ended a very long period of dormancy explosively and with little warning (although with today's technology, we may have seen that eruption coming, but we did not have advanced GPS satellite data to measure deformation, nor did we have the types of seismic knowledge that we do today). Mt. St Helens was a beautiful, conical volcano, which until 1980 was a favorite hiking trail and nature preserve. The eruption, many thousands of times more powerful than a nuclear bomb, wiped out and flattened the landscape for tens of miles around the volcano. The only death was a man ironically named Harry Truman, who refused to leave his mountain home. As many as 57 people were killed in the blast, mostly hikers, and a mountain resident named Harry Truman. One persons ordeal was captured on his camcorder as he attempted to escape the ash cloud, but unfortunately he was unsuccessful. Several others survived lahars and thick ashfall, and lived to tell their stories. This eruption could have been much worse if it occurred in nearly any other Cascades range volcano.... and this is the only eruption that is still fresh in the minds of the US.

There were however eruptions of other Cascades volcanoes within the last century. The eruption of Mt Lassen in 1914-1917 was extremely large, and one of the first eruptions to actually be photographed as it exploded. Huge boulders many tons in mass were flung miles from the summit, pyroclastic flows raged down the sides of the mountain, and ash fall was recorded very far from the volcano. There are very few people alive today who would have witnessed this eruption, and the eruption has all but faded from memory.

Before the Lassen eruption, there was the reported eruption of Shasta in the late 18th century. "Shasta's only historical eruption was observed from the ship of the explorer La Perouse off the California coast in 1786." according to the Smithsonian Global Volcanism Project. While this seems like a long time ago, consider how long St. Helens was dormant for. Shasta, like most other volcanoes in the Cascades still experiences periods of heightened seismicity, and weak geothermal action. Shasta will erupt again, but like St. Helens, it is in a lightly populated area (a town called Weed, CA).

But then there are the more dangerous Cascades volcanoes. Like Vesuvius in Italy, Mt Rainier is considered by many scientists to be the most dangerous volcano in the world in regards to the population surrounding it. Not far (40 miles SW) from Tacoma and Seattle Washington, Mt Rainier looms over the landscape and dominates the skyline. This 4,392 meter tall giant of a stratovolcano last erupted some time in the 19th century, according to tree-ring data and analyzed tephra layers.

The threat from this volcano is three-fold. An eruption would melt the glaciers capping the volcano, causing mudslides and lahars. Even if the volcano doesn't erupt, it can collapse due to hydrothermal action 'rotting' the rocks it is made of. This is currently the biggest worry of geologists, and they have a reason to. Flank collapses have reached all the way to the Puget Sound, and that didn't even require an eruption from the massive hulk. Currently, the volcano steams away at the summit, creating a series of steam carved ice caves, a reminder that it is still very much an active volcano. The worst case scenario for this volcano would be a collapse resulting in an eruption, mudflows, pyroclastic flows, and lahars. Much like St Helens, but far larger.

All of these volcanoes have erupted before, and all of them will erupt again. And thankfully, we will probably known at least a few days before that will happen, but there is no predicting structural collapse of these volcanoes, as there are little to no precursor signals that we could be aware of except for GPS measurements, and they would have to be rather frequent. In any case, if you, like me, live on the US West Coast, it's always good to have a disaster plan. We have frequent earthquakes, and will have volcanic eruptions in the future. It's a matter of when, not if. We even have our own supervolcano, the Long Valley caldera, which has erupted after Yellowstone and still shows deformation, seismicity, and hydrothermal action. Its a good thing any new eruption at Long Valley would likely be a small dome building event, or I might just get worried.

The best course of action, especially if you worry about silly things like 2012, etc, is to have a volcano preparedness kit. Breathing masks, batteries, flashlights, LOTS of bottled water, non-perishable food... if you worry about these things, you should have a supply ready to be used in an emergency. The same goes for earthquakes, wildfires, or any other natural disaster our coast has and will experience again. 

Askja Volcano in Iceland Showing Signs of Warming

Several articles and local bloggers have started to chatter about changes at Askja volcano in Iceland, a volcano with a powerful and violent past. In 1875, Askja erupted in one of Iceland's largest historical eruptions, producing a small caldera now filled by Öskjuvatn lake. Askja has erupted during the 20th century (1900's) producing fissures and lava flows outside of the Öskjuvatn lake, but has remained mostly dormant in recent decades.

The volcano is showing signs of increased thermal activity in the caldera, as well as heightened temperatures from fumeroles and springs. It is unclear at this point as to when exactly the warming started, but it appears to have started somewhere between May of 2010, or earlier. There have been some quake swarms and magma intrusion into the volcanic system since the late 1990's, but none of this activity has resulted in an eruption.

Iceland is still in the middle of the cold season, where the Öskjuvatn lake should be frozen over, however it appears that the lake is now liquid, despite the frigid temperatures and snowfall. This suggests a powerful heat source is indeed keeping the lake from freezing. Some speculate that when the ice melts in Iceland, that the volcanoes can erupt more easily, however that is still only a theory and is difficult to prove or demonstrate. Askja warming up in the middle of Winter would seem to suggest that something is happening deep below, as apparently this is not typical for the volcano in the middle of the cold season.

A NASA Image shows an ice free Askja Lake, and an apparent ash layer covering the snow, which could mean a small eruption from a fumerole or vent has already occurred. This picture is from March 23rd.

Blogger Jon Frimann in Iceland has been posting about this for a week or so, as well as some other news outlets that have taken notice.

An eruption at Askja would likely follow the pattern of its 19th-century activity, with fissure swarms and pahoehoe lava flows (it is a shield volcano, much like Mauna Loa or Kilauea in Hawaii). This would not likely produce another caldera forming event, however that is always a possibility, and given that we have no accurate images of the magma chamber below, it is anyone's guess as to what will really occur (but that's the exciting part about volcanoes with long periods of dormancy, you just never know how a new eruption would manifest).

The Smithsonian GVP characterizes Askja as follows:

"Askja is a large basaltic central volcano that forms the Dyngjufjöll massif. It is truncated by three overlapping calderas, the largest of which is 8 km wide and may have been produced primarily from subglacial ring-fracture eruptions rather than by subsidence. A major rhyolitic explosive eruption from Dyngjufjöll about 10,000 years ago was in part associated with the formation of Askja caldera. Many postglacial eruptions also occurred along the ring-fracture. A major explosive eruption on the SE caldera margin in 1875 was one of Iceland's largest during historical time. It resulted in the formation of a smaller 4.5-km-wide caldera, now filled by Öskjuvatn lake, that truncates the rim of the larger central caldera. The 100-km-long Askja fissure swarm, which includes the Sveinagja graben, is also related to the Askja volcanic system, as are several small shield volcanoes such as Kollatadyngja. Twentieth-century eruptions at Askja have produced lava flows from vents located mostly near Öskjuvatn lake."