August 26 – Well, Blow Me Down

Today’s factismal: The “Year Without A Summer” was not caused by the eruption of Krakatoa.

Stop me if you’ve heard this one before – way back when, there was a massive volcanic eruption that was so loud it was heard in Australia and put so much ash into the air that everything froze and we had a year without a summer. Great story, right? The only problem is that it isn’t; instead, it is two great stories.

The eruption of Mt Saint Helens was actually fairly small as such things go (Image courtesy USGS)

The eruption of Mt Saint Helens was actually fairly small as such things go
(Image courtesy USGS)

The first story is actually the last one. Back in 1815, Mount Tambora in Sumbawa exploded in the largest volcanic eruption in recorded history. It turned 24 cubic miles of rock into dust and debris and was loud enough to be heard for 1,200 miles. The eruption alone killed some 11,000 people. Worse, all of that dust in the air dropped the global temperature by a full degree below which was enough to kill crops and cause starvation in many areas; experts estimate that this killed another 60,000 people. (For comparison, the global temperature is now nearly two degrees above average this is not a good thing, either.)

When Pinatubo erupted in 1991, it cooled the planet by about 0.25 °

When Pinatubo erupted in 1991, it cooled the planet by about 0.25°

The second story happened nearly 68 years later at a spot nearly 900 miles away. On August 26, 1883, Mount Krakatoa erupted violently. The eruption wasn’t a surprise as the mountain had been spewing “fire fountains” into the air for months. What was a surprise was the size of the eruption; experts think that the neck of the magma chamber had become plugged with debris. Like holding your thumb over the neck of a soda bottle while shaking it, that allowed the pressure to build until it finally spewed out. That would have been bad enough, but the eruption created a caldera that went down below sea level. As the ocean water rushed in, it created a phreatic (steam) explosion, resulting in a sound so loud it could be heard 2,600 miles away and a tsunami that devastated coastlines across the Pacific and killed some 36,000 people. Because this was a smaller explosion than Tambora, only a few cubic miles of dust were tossed into the stratosphere and the weather was only made chilly instead of cold. As a result, there wasn’t the mass starvation of the previous eruption.

Exciting as the two eruptions were and interesting as the volcanology is, there is another facet to the two events that has a far more practical effect on us today: their effect on the weather. Since modern meteorological systems weren’t in place during the two eruptions (heck, meteorology hadn’t even been invented when Tambora blew!), climatologists must search for clues to their effects using old ship’s logs and diaries. And that’s where you come in. At Old Weather, you can look through the logs of sailing ships to discover what the weather and other things were like. By highlighting those entries, you help the folks who are trying to figure out what our new weather will do next. To learn more, blow on over to:
https://www.oldweather.org/

May 18 – Pop Life

Today’s factismal: There have been over 1,200 earthquakes under Mount St Helens since 2010.

If you’ve been reading the news (or Facebook), you’ve probably heard that there has been a recent swarm of about 20 earthquakes under Mount St Helens. And that can be sort of scary because thirty-six years ago today, Mount St Helens reminded us of just how powerful nature can be when it erupted some 4 billion cubic yards of rock. The eruption tore off most of the top of the mountain by noon, shrinking it from  9,677 ft tall to 8,363 ft and spread ash across fifteen states. The forest was blasted away for 17 miles from the northern side and the Columbia River shipping channel 70 miles away was blocked by the largest landslide in recorded history. And yet, thanks to the work of the vulcanologists on the scene, only 57 people lost their lives in the eruption.

The eruption was actually fairly small as such things go (Image courtesy USGS)

The eruption was actually fairly small as such things go
(Image courtesy USGS)

But will the mountain erupt again? If you ask a geologist, the answer is both yes and no. Because Mount St Helens is on an active subduction zone, we know that it will keep getting fed magma so it will definitely erupt sometime. But because we’ve seen similar swarms for the past decade, it is unlikely that Mount St Helens will erupt any time soon. There have been more than 1,200 earthquakes since 2010; that works out to be about ten per month. So getting twenty in two weeks isn’t that unusual. And because the recent swarm is about the same place that previous swarms have been, it is unlikely that the events are due to large amounts of magma moving around; indeed, they could have been caused by magma cooling and contracting which would reduce the chances of an eruption!

The location of earthquakes over the past decade show that the recent swarm isn't that unusual (Image courtesy the Pacific Seismometer Network)

The location of earthquakes over the past decade show that the recent swarm isn’t that unusual
(Image courtesy the Pacific Northwest Seismometer Network)

Scientists have been monitoring the volcano for years, starting well before the 1980 eruption. They monitor the earthquakes associated with magma movement  with a number of seismometers and have flown over the volcano repeatedly to capture images of changes in the mountain slopes; they have also put instruments into place to measure the tilting of the ground and its temperature. This information allowed them to predict when the volcano would erupt in 1980 and continues to help us understand what will happen next.

Mount St. Helens is just one of many, many volcanoes on the Pacific coast (Image courtesy USGS)

Mount St Helens is just one of many, many volcanoes on the Pacific coast
(Image courtesy USGS)

That information is important because most people forget is that Mount St Helens isn’t the only volcano in the Cascades range. There are over 100 volcanoes stretching from California to British Columbia. All of them are caused by the subduction of the Juan de Fuca and Gordo plates under the North American plate; this is also what has created the Cascades mountains and the large number of large earthquakes in the region. And it is that motion that tells us that someday (geologically) soon, one of them will erupt just as Mount St Helens did.

California's earthquakes and Washington's volcanoes have the same cause (Image courtesy USGS)

California’s earthquakes and Washington’s volcanoes have the same cause
(Image courtesy USGS)

If you’d like to help scientists learn more about volcanoes and predict the next eruption, then why not join NetQuakes? You’ll keep a seismometer in your home and help monitor earthquakes and volcanic eruptions!
http://earthquake.usgs.gov/monitoring/netquakes/

November 24 – Volcano-no

Today’s factismal: Many of the words for lava are Hawaiian.

If you ask any geo-geek about molten rock and the first question that he’ll ask is “inside the ground or on top of it?” That’s because geology has different names for molten rock depending on where it is. When the molten rock is inside the ground, it is called magma. When it is exposed on the surface, it is called lava. And, unlike many other pedantries, this distinction actually makes sense. That’s because lava meets the air (or the water) on one side, which allows it to cool more quickly which means that it tends to have smaller crystals but magma is all wrapped up in a blanket of rock, which means it cools more slowly which means it tends to have bigger crystals.

This Hawai'i volcano makes very small crystals (Image courtesy USGS)

A Hawai’i volcano making a’a
(Image courtesy USGS)

And that isn’t the only place where volcanic terminology gets down and detailed. For example, when basaltic lava erupts at a low temperature (just about 2000°F), it is stiff and moves slowly; as a result, the outer surface breaks off in a layer of small pebbles known as clinkers. When the mass cools, it is called a’a, from the Hawai’ian for “stony lava”. But when the lava is nice and hot, it is very thin and moves quickly. This means that the upper surface, which forms a skin like that on hot milk, The skin cools into a distinctive form known as pahoehoe or “smooth lava”. And if the basaltic lava erupts under water, it forms small little pillows that we call (wait for it) pillow basalts.

Two geologists standing near a lava flow (Image courtesy USGS)

Two geologists standing near a pahoehoe lava flow
(Image courtesy USGS)

If you’d like to learn more about the weird and wonderful world of volcanoes, why not head on over to the USGS Volcano web site?
http://volcanoes.usgs.gov/

August 18 – Thar She Blows!

Today’s factismal: On average, a volcano erupts somewhere on Earth each week.

If you’ve been reading the news, then you may have seen an article about Cotopaxi, a volcano located near the capital of Equador. Right now, Cotopaxi is shooting plumes of ash seven miles up into the stratosphere and warming up the snow that covers its summit. Of the two, the snow is the more dangerous thing; when snow melts and mixes with volcanic ash, it can create a lahar which can roll downhill at up to 60 mph covering everything in a layer of steaming mud; it was a lahar that buried Pompeii and a lahar that destroyed Martinique.  But, worrisome as that is, the eruption itself is nothing unusual. There are about 1,500 volcanoes scattered across the globe and every week one or another of them erupts.

A fire fountain in Hawai'i (Image courtesy USGS)

A fire fountain in Hawai’i
(Image courtesy USGS)

Of course, some of the eruptions last longer than others. (For eruptions lasting longer than four years, seek your geophysicist’s advice.)  Stromboli has erupted at irregular intervals for the past thousand years or so but only for a  month or so each time.  But Mauna Loa has erupted almost continuously for at least 700,000 years. The one thing that eruptions have in common is that they are all different, thanks to the types of magma/lava involved and the location of the volcano. (Remember that it is magma when it is in the Earth and lava when it is on the surface.) A volcano with a hot, thin lava that spews into the air can create a fire fountain like the one at Mauna Loa. A volcano with a thick, cooler lava that erupts under water can create a phreatic explosion that blasts bits of the volcano for miles around, like Tambora did back in 1815. Right now, Cotopaxi looks more like a mini-Tambora than another Mauna Loa, but we never know.

Deception Island in Antarctica is a volcano that last erupted in 1969 (My camera)

Deception Island in Antarctica is a volcano that last erupted in 1969
(My camera)

And that’s why we watch volcanoes – so we can learn more and maybe predict what will happen next. If you’d like to do more than watch, then why not download the myVolcano app from the British Geological survey?
https://www.bgs.ac.uk/myVolcano/

January 18 – Pass The Marshmallows!

Today’s factismal: Lava-roasted hamburgers is a traditional meal for geologists working on volcanoes.

Let’s face it; geologists are weird. (Truth in advertising: I’m a geophysicist, which is just like a geologist only I do math. Back to the geologists…) They travel to exotic places in order to look at rocks and drink beer. They spend weeks in the field looking at rocks and drinking beer. And then they take their new rocks back to the lab where they look at the rocks and drink beer. And by doing this they have learned some amazing things about our planet (and others). With a little help from geophysics, they have learned how mountains form and why we have oceans (it all has to do with the density of the rocks). They have discovered what makes earthquakes and why planets are round. And most amazingly, they have learned how to cook with lava.

Geologists at work, measuring how fast lava flows (Image courtesy USGS)

Geologists at work, measuring how fast lava flows
(Image courtesy USGS)

Of course, the beer probably had something to do with the last. When you are out in the field for weeks at a time with nothing to look at but ricks and dirt-encrusted geologists, you start to look for a source of amusement. And cooking with lava is almost as amusing as it is dangerous; though there have been no deaths reported from cooking with lava, there have been a lot of near-misses. That’s because most people (geologists included) don’t have a good idea of what lava is really like. They think of it as being like really hot water because they see glorious fire fountains spewing lava hundreds of feet into the air.

A fire fountain in Hawai'i (Image courtesy USGS)

A fire fountain in Hawai’i
(Image courtesy USGS)

But what lava is like is really, really hot fudge. It is so hot that it literally glows; you know those elements in your oven that heat up and glow – yeah, just like that, only twice as hot. And lava is thick and sticky like fudge. If you were to stand on a thick slab of fudge, then you would slowly sink into it and you’d have a heck of a time getting it off of your shoes. The same is true of lava. It is sticky and so thick that you can stand on it for several minutes before you notice that you are slowly but surely sinking into a glowing hot mass of death. (This is why geologists laugh themselves silly when Gollum sinks into the lava – it just ain’t gonna happen.)

Two geologists standing near a lava flow (Image courtesy USGS)

Two geologists standing near a lava flow
(Image courtesy USGS)

But because lava is hot and oozes slowly, it makes a great way to cook hamburgers, provided that you are suicidally brave or so intellectually involved that you forget about the danger (either of which is a good description of your average geologist). The heat sears the hamburgers so that they stay juicy, and it is intense enough that they cook quickly minimizing the amount of time you have to spend next to an open oven that will roast you alive given half a chance. And so, when volcano geologists work near an active lava flow, it is traditional for them to cook hamburgers on it. To learn more about volcanoes and geologists, why not head on over to the USGS Volcano web site:
http://volcanoes.usgs.gov/

August 23 – Bardarbing, Bardarbang, Bardarbunga!

Today’s factismal: The Bardarbunga volcano in Iceland has begun to erupt!

If you are a geologist, these are exciting times. Not only do we finally have a theory that explains how mountains and volcanoes form, we’ve got all kinds of instruments that helps us gather the data we need to test the theory and make it better. (That’s what scientists do, you know – we hatch ideas, carefully feed them on data until they become hypotheses, and then test them with yet more data leaving only the strongest behind as theories. And then we start all over again with the ideas that the theory spawns.)  Thanks to the Cold War, we’ve got seismometers located all across the globe; though they were put there to detect atomic bomb tests, they also record earthquakes which helps us learn more about the inside of the Earth. And thanks to the Cold War, we’ve got satellite altimetry across the globe; though it was created to help us detect bomb craters, it also helps us to measure how the Earth’s surface tilts and where things in the upper crust are moving. And thanks to the Cold War, we’ve got satellites that measure the change in gravity; though they were created to help track submarines (and to make our missiles more accurate), they also tell us where materials in the Earth change density. And, thanks to the Cold War (do you detect a theme here?), we’ve got GPS; though it was created to help the military move around, it also helps us track the movement of continents and mountains. And all of that data has lead in turn to a deeper understanding of the Earth.

And though a lot of that understanding is purely academic, such as the discovery that there is the equivalent of three ocean’s worth of water stored in the minerals of the Earth’s mantle, a surprising amount of it is very practical indeed. Understanding how the plates move around on the Earth has led to discovering new deposits of gold, silver, and diamonds (not to mention oil and gas), and to learning which areas are most at risk for earthquakes and volcanoes. Even better, it has helped us learn how to predict volcanic eruptions (we’re still working on predicting the timing of earthquakes). One of our earliest successes was Mt. St Helens; the scientists in the area were able to predict the eruption and save the life of everyone who was willing to evacuate. And today we have another example of that science at work in the eruption of Bárðarbunga (Bardarbunga {bar-dar-BUNG-ah!} to everyone but the Icelandics).

Like Mt. St Helens, Bardarbunga is a stratovolcano. That means that it is a tall, cone-shaped volcano made up of alternating layers of ash and lava fed from a subterranean magma chamber that sometimes erupts explosively (creating the ash) and sometimes erupts more passively (pouring out the lava). These are among the most common volcanoes on Earth and create some of the most spectacular eruptions (e.g., Krakatoa) as well as some of the least interesting ones (e.g., Stromboli, “the lighthouse of the Mediterranean”). Where Bardarbunga and Mt. St Helens differ is that Mt. St Helens is created by plate tectonics and Bardarbunga is created by a mantle plume. (That’s part of the “testing the theory” we discussed.) Where plate tectonic volcanoes are formed when subducting plates release a little water that stimulates magma production which then creates the volcano, mantle plume volcanoes are created by extra-light material coming from deep within the mantle. We’re still arguing over why mantle plumes should exist, as well as how many of them there are; everyone agrees on Iceland (where Bardarbunga is) and Hawai’i, but that’s it.

Location of earthquakes around the Bardarbunga volcano (Image courtesy aaaa)

Location of earthquakes around the Bardarbunga volcano
(Image courtesy Iceland Met Office)

The number of earthquakes per day (Image courtesy Iceland Met Office)

The number of earthquakes per day
(Image courtesy Iceland Met Office)

 

One thing that we’re not arguing over is that Bardarbunga is erupting. Starting about two weeks ago, seismologists noticed that the number of earthquakes, and especially the shallow earthquakes, in the area had taken a steep jump upward. Because adding magma to a region “stretches” the surface material, you always hear creaks and groans in the form of small earthquakes when it happens. In addition, the geophysicists in the area using GPS had noticed that the ground was starting to tilt; that’s another strong hint that there was magma moving into the area. And so Iceland raised the eruption threat to “Orange” (right below “Red” or “Watch out – the lava’s a’coming!”).

Today, the eruption threat was raised to Red as a small plume of ash and smoke was seen coming from the ice covering Bardarbunga. And that is the second important way that Bardarbunga differs from Mt. St Helens. Where Mt. St Helens had a light dusting of snow on its top, not more than a hundred feet thick, Bardarbunga is buried beneath a glacier; this is even more impressive when you realize that the volcano’s top lies 6,600 ft above sea level. The Vatnajökull (vat-na-JOKE-ull) glacier covering the volcano averages 1,300 ft thick and so forms a most excellent plug over the volcano. And that means that we may get an great view of a subglacial eruption!

Satellite image of Iceland; Bardarbunga is in the middle of the large chunk of ice (Image courtesy NASA)

Satellite image of Iceland; Bardarbunga is in the middle of the large chunk of ice
(Image courtesy NASA)

When hot lava meets cold ice, several things, all of which are fascinating, happen. The heat from the lava can melt the ice, forming a subglacial lake that eventually breaks through and rushes downhill like a crazed wet, weasel; this “jökulhlaup” (“glacier run” {yokel-oop}) can carve valleys and denude meadows faster than a politician can pocket a bribe. If there is enough ash mixed in the water, it forms a lahar which is basically a mud flood moving sixty miles an hour and not stopping for directions;in 1985, a lahar killed 23,000 people in Columbia. If the lava is erupted more quickly than the water can drain, then the heat may cause the water to turn into steam creating a steam explosion. This can then fling pieces of lava as large as a house for miles around.

Even if none of these things happen, the volcano will still put out ash and carbon dioxide and other particulates. The ash can make flying hazardous as the sharp edges eat away at jet turbine blades and propellers and literally sand-blast windshields into opacity. It is for this reason that planes are directed to fly well away from any erupting volcano. The carbon dioxide may seem like a lot, but it is actually relatively little. If this is a typical volcanic eruption, then it will put out about 500,000 m3 of lava and will eject about 8,300 tons of CO2 into the atmosphere, along with 2,000 tons of SO2 and 6,300 tons of H2O. In comparison, a car emits about 5.5 tons of CO2 per year, so Bardarbunga will add less CO2 than the amount generated by Houston traffic over the length of the eruption. But the SO2 is particularly interesting. As Franklin suggested back in 1784, volcanoes can cool the planet. We are still arguing about how they do so, but we know that the SO2 plays a key part. It acts to reflect sunlight back into space, helping to cool the planet. But such effects are short-lived; when Pinatubo erupted in 1991, it cooled the Earth by nearly 0.7°F but temperatures were back to normal by 1993.

So right now we’ve got an erupting volcano with lots of potentially interesting effects. Grab the popcorn and stay tuned!

August 29 Update: The eruption has subsided and Iceland has reduced the threat level to “orange” (possibly dangerous but not certain).

May 18 – Mounting Concerns

Today’s Factismal: Mount St. Helens erupted 34 years ago today!

Thirty-four years ago today, Mount St Helens reminded us of just how powerful nature can be. Beginning at 8:32 AM, the eruption tore off most of the top of the mountain by noon and spread ash across fifteen states. The mountain shrank from 9,677 ft tall before the eruption to 8,363 ft tall after, removing nearly 4 billion cubic yards of rock in the largest landslide in recorded history. The blast cleared the forest for 17 miles from the northern side and spawned a mudflow that blocked the Columbia River shipping channel 70 miles away.

Amazingly, only 57 people were killed in the explosion. This was because scientists had been monitoring the volcano for years, recognizing that it was potentially active, not inactive. They had established a number of seismometers to measure the earthquakes associated with magma movement and has flown over the volcano several times to capture images of the incipient eruption and to put instruments into place to measure the tilting of the ground and its temperature (among other things). This information allowed them to predict when the volcano would erupt and to get most of the people to safety.

MtStHelens_IKO_2005068
1cascade_map

Though many people wonder when Mt St Helens will erupt again, vulcanologists are more interested in learning when the other volcanoes in the Cascades will erupt. There are over 100 volcanoes in Mt St Helens’ chain, stretching from California to British Columbia. All of them are caused by the subduction of the Juan de Fuca and Gordo plates under the North American plate; this is also what has created the Cascades mountains and the large number of large earthquakes in the region.

If you’d like to help scientists learn more about volcanoes and predict the next eruption, then why not join NetQuakes? You’ll keep a seismometer in your home and help monitor earthquakes and volcanic eruptions!
http://earthquake.usgs.gov/monitoring/netquakes/