Questions for Kristi Wallace

Learn more about my research In October, 2007, Kristi Wallace answered visitors questions about geology and volcanoes.

Your Comments, Thoughts, Questions, Ideas

Anonymous's picture
Anonymous says:

Hi. Has there been any volcanic activity at the Katmai volcano since the great eruption of 1912? Is this volcano monitored by the AVO? Sincerely, Al in Columbia Heights, MN

posted on Fri, 10/19/2007 - 10:48am
Kristi Wallace's picture
Kristi Wallace says:

Well, there are no credible reports of historic eruptions in the Katmai group except at Novarupta in 1912 and at Trident in 1953 – 1968. This does not mean that there has been no “volcanic activity” as you have asked. Earthquake swarms are common within the Katmai group but so far none have amounted to an eruption. Katmai also seems to respond to large regional earthquakes. The Alaska Volcano Observatory (AVO) does in fact monitor Katmai Volcano and the other volcanoes in the group (Snowy, Griggs, Trident, Novarupta, Martin, and Mageik) very closely and we have a total of 10 seismometers installed amongst these volcanoes.

posted on Fri, 10/26/2007 - 8:32pm
Anonymous's picture
Anonymous says:

How come there aren't any volcanoes in Minnesota?

posted on Fri, 10/19/2007 - 10:48am
Kristi Wallace's picture
Kristi Wallace says:

Well there are no modern volcanoes in Minnesota today mainly because Minnesota is not near a tectonic plate boundary. Basically the outer most solid layer of the earth (the land that we walk upon not the earth’s mantle or core) is broken into many plates that float upon the earths more fluid mantle. The boundaries between these plates often have volcanoes and or major earthquakes because of the energy created by colliding, pulling apart, or moving past one another. The closest plate boundary to Minnesota is the Mid-Atlantic Ridge out in the middle of the Atlantic Ocean. To the west, another major plate boundary is all along the west coast of the U.S., a pretty volcanically active region. That all being said, there have been volcanoes in Minnesota in the past, the very distant past called the Precambrian. There were two periods of volcanism in Minnesota during the Precambrian, one about 2,700 million years ago (mya) and another about 1,000 million years ago (mya). Volcanic activity from the earlier period (2,700 mya) was caused by collision of microplates to the Canadian Shield (of which Minnesota is part of) which created a whole lot of energy ( and thus melting). Masses of land were running into Minnesota via plate tectonics resulting in growing of the North American continent. Volcanic rocks from this period are buried beneath glacial deposits. Volcanic activity that occurred 1,000 mya resulted from a great continental rift (tectonic plates pulling apart) from eastern Lake Superior to Kansas. Much of the molten rock never reached the surface, but solidified underground. Lava that reached the earth's surface cooled in huge overlapping flows, found now along the north shore of Lake Superior mostly as dark-colored basalt. Lake Superior agates formed in the cavities left by gas escaping the cooling lava. Sugarloaf Point SNA, on the North Shore, is a prime example of volcanic formations dating from this period.

posted on Fri, 10/26/2007 - 7:48pm
Carolyn's picture
Carolyn says:

What is the largest volcano in the world? Has it ever erupted?

posted on Fri, 10/19/2007 - 3:08pm
Kristi Wallace's picture
Kristi Wallace says:

The largest volcano in the world is Mauna Loa in Hawaii. It has a volume of about 80,000 cubic kilometers (19,00 cubic miles) and rises gradually to more than 4 km above sea level. Its long submarine flanks descend to the sea floor an additional 5 km, and the sea floor in turn is depressed by Mauna Loa's great mass another 8 km. This makes the volcano's summit about 17 km (56,000 ft) above its base! The enormous volcano covers half of the Island of Hawai`i and by itself amounts to about 85 percent of all the other Hawaiian Islands combined.

Mauna Loa is among Earth's most active volcanoes, having erupted 33 times since its first well-documented historical eruption in 1843. Its most recent eruption was in 1984. Mauna Loa is certain to erupt again, and we carefully monitor the volcano for signs of unrest.

posted on Fri, 10/26/2007 - 8:11pm
Rich's picture
Rich says:

Is there any way to harness the power of an active volcano?

posted on Fri, 10/19/2007 - 4:14pm
Kristi Wallace's picture
Kristi Wallace says:

Why certainly, it is called GEOTHERMAL power and there are a whole lot of people out there with this topic on their minds considering our current energy crisis. The term literally means “earth” (GEO) plus “heat” (THERMAL). Basically, geothermal energy is generated by converting hot water and steam into electricity. Unlike other techniques for generating electricity where you have to heat the water (buy using fossil fuels or nuclear energy), the water from a geothermal plant is already hot so it is considered a GREEN energy. Since volcanoes are associated with hot magma, they are likely places to host geothermal power plants. Iceland is a perfect example of a place where geothermal energy is used, in fact it is their primary form of power production. This makes perfect sense because Iceland sits on top of the Mid Atlantic Ridge, a chain of underwater volcanoes in the Atlantic Ocean where magma comes to the surface as the two tectonic plates move away from one another (spreading center). Geothermal electricity has been generated in the U.S. since about the early 1900’s. I should mention that geothermal power does not always have to be associated with a volcano. There are plenty of places on our earth where hot spots (magma chambers below the surface that never erupt and therefore are not considered volcanoes) make the ground plenty hot for generating electricity.

posted on Fri, 10/26/2007 - 6:57pm
Anonymous's picture
Anonymous says:

How long is it between volcano eruptions? is there really a set # or does a volcano just go off when ever it wants to?

posted on Sun, 10/21/2007 - 2:29pm
Kristi Wallace's picture
Kristi Wallace says:

Humm, interesting question. The answer is not straight forward and it might help to first know that an individual eruption may go on for many months to years as is the case in Hawaii for example and that an eruption may include many phases, some relatively quiet periods with little to no activity at the surface (all the rumbling is going on below the surface in the form of earthquakes caused by magma and fluid movement) and some more explosive or effusive phases where things like lava flows and/or ash plumes are produced. So when we talk about eruptions, it is important to recognize that a single eruption (as they later come to be referred) may in reality have included for example, ten ash plumes over a period of six months. That being said, the period between eruptions is not something that we have been able to model or predict because there does not seem to be much periodicity in volcanic activity. Some volcanoes tease us; for example, Augustine Volcano, in Alaska had a track record of erupting every 10 years for three decades in a row since the 1960’s so we started to expect an eruption in the 1990’s but it never happened…that is until 2006, some 10 years late. This is a topic that we are very interested in knowing more about and continue to study. Excellent question!

posted on Fri, 10/26/2007 - 6:23pm
Anonymous's picture
Anonymous says:

how many volcanoes are in the world?

posted on Wed, 10/24/2007 - 10:42am
Kristi Wallace's picture
Kristi Wallace says:

The most recent count that I am aware of says there are about 1500 volcanoes that have erupted in the past 10,000 years. Of those about 800 have been historically documented or written down by humans.

Having said that, the definition of "volcano" is important in answering the number question because usage has varied widely. The term “volcano" has been applied to individual vents-measured in meters, through volcanic edifices-measured in tens of kilometers, to volcanic fields-measured in hundreds of kilometers. The problem is particularly difficult in Iceland, where eruptions separated by many tens of kilometers along a single rift may share the same magmatic system. A "volcanic field," such as Mexico's Michoacán-Guanajuato field (comprising nearly 1,400 cinder cones, maars, and shield volcanoes derived from a single magmatic system) may be counted the same as a single volcanic edifice. Perhaps the most honest answer to the number question is that we do not really have an accurate count of the world's volcanoes, but that there are at least a thousand identified magma systems, on land alone and likely to erupt in the future.

There is a good book called Volcanoes of the World, by Tom Simkin and Lee Siebert which has lots of nice maps. It is published by Geoscience Press, PO Box 42948, Tuscon, Arizona, 85733-2948, USA.

posted on Fri, 11/02/2007 - 2:04pm
Soupy Man's picture
Soupy Man says:

Why did Mount Saint Helens erupt? Was it because of an earthquake?

posted on Thu, 10/25/2007 - 7:53pm
Kristi Wallace's picture
Kristi Wallace says:

The eruption of Mount Saint Helens (MSH), on a grand scale, has to do with plate tectonics: the Juan de Fuca plate is subducted under the North American Plate because it is denser and parts of the subducted plate begin to melt as the are pushed down toward the hot mantle. This melted rock (or magma) rises toward the surface to feed the Cascade volcanoes (so this process is the same of all the Cascade volcanoes, not just MSH). Every once in a while enough magma accumulates under a volcano that it starts to expand and rise to the surface. This magma is very viscous (thick and sticky rather than thin and watery) and contains dissolved gasses (like carbon dioxide dissolved in soda before you open the can). These bubbles want to expand, and this causes the pressure within the magma to go up. As the magma continues to move upward, more and more bubbles grow and want to expand, causing the pressure to build. Because the magma that was erupted in 1980 was so viscous, the bubbles couldn't really float through it to escape out the top so they just kept building the pressure. In the case of the big 1980 eruption, the magma accumulated high in the volcano and as it did, it caused a large, visual bulge in the north flank. Eventually, the pressure of the magma exceeded the strength and weight of the mountain and a large debris avalanche occurred (this may have been initiated by an earthquake), where most of the north flank of the volcano was swept away down slope. As soon as the weight of the top of the volcano was removed the pressure dropped allowing the gasses to come out of solution, form bubbles, and escape and the explosive phase of the MSH eruption began. Since the 1980 eruption there have been smaller explosive eruptions. The main reasons these have been smaller is that smaller amounts of magma have been involved, and also there is less mountain to allow the pressure to build. The 1980 eruption at MSH is only the most recent large eruption at that volcano. The oldest deposits at MSH are 40,000 to 50,000 years old so these sorts of eruption have occurred before.

posted on Fri, 11/02/2007 - 2:37pm
Joe's picture
Joe says:

What inspired you to pursue studying volcanoes?

posted on Sat, 10/27/2007 - 12:54pm
Kristi Wallace's picture
Kristi Wallace says:

Well I have to say, the incredible people that I work with and then the obvious ah-inspiring nature of working around volcanoes. I was born and raised in Alaska so I am accustomed to being surrounded by amazing geology with all of our rivers, mountains (some of which are volcanoes), glaciers, lakes etc. so geology has always been on my mind whether I knew it or not . As an undergraduate student in college I got a position with the U.S Geological Survey (my current employer) where I was first exposed to geology as academic field of study. I got to work on maps and participate in many field studies and fell in love with everything. There is something about geologists as a whole that is settling; they are a breed of people that really have fun and enjoy their work and that was very attractive to me. We spend a lot of time together in the field, sleeping in tents, thinking about what we see, sharing our ideas, eating together, and consequently we bond in a way that makes our office jobs (and communication) that much stronger. The best part about my job is that I get to be in the field surrounded by beautiful, incredible sights, sounds, smells, events and then take it all back to the office where I analyze samples in my laboratory and from there get to pull all the results together on paper and share them others. I think geology is one of those fields of study that most people know a whole lot more about than they think they do; we live in a world of geology and start observing as soon as we can see. Thanks for that question!

posted on Fri, 11/02/2007 - 1:25pm
Anonymous's picture
Anonymous says:

During the course of your activities studying the volcano, are you ever in any danger?

posted on Sat, 10/27/2007 - 12:58pm
Kristi Wallace's picture
Kristi Wallace says:

Probably, but I don’t think any more than if I were driving my car to work or taking a hike in the mountains around Anchorage. Safety of its employees is very important to the U.S. Geological Survey so we are well-prepared for the work that we do in the field. In a typical year, we study volcanoes that are not erupting but are considered active. Between eruptions is a good time to map deposits from lava flows, mud flows, ash fall, etc. to understand what the volcano is capable of, so the volcano does not present any immediate danger. I suppose the greatest danger is in working around bears, flying in small aircraft like helicopters and fixed-wing planes, climbing on steep terrain etc. but we are required to take a variety of safety training classes prior to working in the field. During eruptions we do visit our volcanoes, sometimes between explosive blasts (where ash plumes are generated) but these visits are well choreographed and we have constant communications with our office who can tell us if activity is ramping up (based on seismic or earthquake data) or if we are safe to grab a sample or install another piece of monitoring equipment. These sorts of field expeditions are exhilarating to say the least but I have never felt unsafe.

posted on Fri, 11/02/2007 - 1:49pm
Anonymous's picture
Anonymous says:

Do you know anything about Olympus Mons - the HUGE volcano on Mars? Is it still active?

posted on Sun, 10/28/2007 - 3:42pm
Kristi Wallace's picture
Kristi Wallace says:

Well this definitely is not my area of expertise so I had to consult my federal partner, NASA to answer your questions. Olympus Mons is the largest volcano in the solar system and as you indicated, is located on the planet Mars. Olympus Mons is a shield volcano much like Earth’s Hawaiian volcanoes but much, much larger. The altitude of Olympus Mons is three times the altitude of the largest peak on Earth, Mt. Everest, and is as wide as the entire chain of Hawaiian Islands. Martian volcanoes were built in a manner similar to that in which the Hawaiian Islands came into being on Earth, namely by a hot plume, rising from the deep interior of the planet, which builds land on the surface. The size of this volcano has something to do with Mars not being broken into plates (like the Earth is) and also suggests that Mars had already cooled sufficiently to form a lithosphere thick enough to support large volcanoes without allowing them to sink.

As far as volcanic activity today, Olympus Mons does not appear to be active. Based on crater size and frequency counts (this is how things are dated on other planets), the surface of the western scarp has been dated from 115 million years in age down to a region that is only 2 million years old. This is very recent in geological terms, suggesting that the mountain may yet have some ongoing volcanic activity.

I suggest that you refer to the NASA web site for more on this cool volcano; I am stuck on earthly volcanoes.

posted on Fri, 11/02/2007 - 2:59pm
Anonymous's picture
Anonymous says:

are all volcanoes considered active?

posted on Fri, 11/02/2007 - 12:36pm
Kristi Wallace's picture
Kristi Wallace says:

Good question; No not all volcanoes are considered active, in fact this is a confusing topic because the definition of “active” is inconsistent. Some consider a volcano active if it has had volcanic activity in historic times or in recorded history, e.g. when humans started keeping records. This is a silly definition because in some places (like Alaska) historic times began only a short time ago (1760 in Alaska, 1000’s of years in Europe, etc.). Basically a volcano is considered active if either 1) it has erupted in recent times and 2) shows signs of activity (for example seismicity or inflation). There are a couple other terms volcanologists use to describe a volcanoes activity, dormant and extinct. A dormant or sleeping volcano is a volcano that has been quiet for a long time, but still has signs it may erupt again. A volcano becomes dormant when the vent is blocked by hardened lava, called a plug, or if the magma seeps back under the earth’s crust. Volcanoes can be dormant for hundreds of years. Then suddenly a volcano will erupt again. The volcano is then classified again as an active volcano. An extinct volcano is one that has not erupted for thousands of years, shows no signs of activity, and is highly eroded.

posted on Sat, 11/10/2007 - 1:52pm
Thor's picture
Thor says:

Today I had a museum visitor ask about the dangers to Minnesota from a possible volcanic eruption in the Yellowstone National Park area. I've heard that eruptions occur there about every 60,000 years and that it's been about 60,000 years since the last eruption. Does this visitor have a lot to be worried about? She told me she was losing sleep over this.

posted on Fri, 11/02/2007 - 4:06pm
Kristi Wallace's picture
Kristi Wallace says:

Well I can understand why this is a stressor to the public considering the Hollywood film production and Discovery Channel coverage of this amazing volcanic system. It is important to understand that we cannot say that we are overdue for an eruption when we only have 3 data points from past large eruptions from Yellowstone. The three eruptions occurred 2.1 million, 1.3 million and 0.64 million years ago. The two intervals are thus 0.8 and 0.66 million years, averaging to a 0.73 million-year interval implying that we are still about 90,000 years away from the time when we might consider calling Yellowstone overdue for another caldera-forming eruption.

Nevertheless, we cannot discount the possibility of another such eruption occurring some time in the future, given Yellowstone's volcanic history and the continued presence of magma beneath the Yellowstone caldera. So although we can’t say (we don’t know) when another large eruption may occur, Yellowstone is monitored for signs of volcanic activity by YVO scientists who detect earthquakes using seismographs and ground motion using GPS (Global Positioning System). YVO has not detected signs of activity that suggest an eruption is imminent.

Yellowstone's volcanic and hydrothermal history suggests the potential for various kinds of eruptions in the future. The likelihood of a certain type of eruption occurring in the future can be judged by how often eruptions have occurred in the past.

1. The most likely type of eruption would not be volcanic but, rather, hydrothermal. This type of small, but still explosive eruption can occur from shallow reservoirs of steam or hot water rather than molten rock. These reservoirs are the sources of Yellowstone's famous geysers, hot springs, and fumaroles. Such explosions could blast out shallow craters more than a kilometer wide; as has occurred in the northern Yellowstone Lake Basin, including Mary Bay and nearby Turbid Lake and Indian Pond, and in western Yellowstone National Park north of Old Faithful. Each of these craters was produced by steam blasts within the past few thousand years.

2. The most likely type of volcanic eruption at Yellowstone would produce lava flows of either rhyolite or basalt; rhyolitic lava eruptions could also include explosive phases that might produce significant volumes of volcanic ash and pumice. Such eruptions could range in size from smaller than the 1980 eruption of Mt. St. Helens through much larger than the 1991 Mount Pinatubo eruption.

3. The least likely but worst-case volcanic eruption at Yellowstone would be another explosive caldera-forming eruption such as those that occurred 2.1 million, 1.3 million, and 640,000 years ago. However, the probability of such an eruption in any given century or millennium is exceedingly low- much lower than the smaller eruptions mentioned above.

posted on Sat, 11/10/2007 - 2:10pm
Anonymous's picture
Anonymous says:

Have you studied volcanoes anywhere else in the world?

posted on Sun, 11/04/2007 - 10:46pm
Kristi Wallace's picture
Kristi Wallace says:

Well it depends on what you mean by “study”, in order to understand Alaskan volcanoes, I have to study other volcanic systems that are similar to our situation in Alaska so yes I have studied volcanoes all over the world but only as far as reading literature, and meeting with researchers from other countries and observatories. In terms of doing fieldwork and working on products from volcanoes other than from Alaska, no I do not study volcanoes outside the U.S.; we have too much to do here in Alaska. However, since our agency has a very close link with volcano observatories in Russia, it is likely that I will work in Kamchatka in the near future.

posted on Sat, 11/10/2007 - 1:30pm
Anonymous's picture
Anonymous says:

What, in your opinion, is the coolest (most interesting/best story) volcano?

posted on Sun, 11/04/2007 - 10:48pm
Kristi Wallace's picture
Kristi Wallace says:

Put me on the spot eh… this is not easy, mostly because I want to say an Alaskan volcano but the reality is that we still have tons to learn about our volcanoes and written history only began a short time ago when Russian hunters and settlers came in the mid 1700’s so we don’t have many records. Maybe I will take the opportunity to tell a neat story about one large and recent eruption in Alaska. Part of the difficulty is defining “cool” when it comes to volcanoes; I can think of a million stories, a million ah-inspiring days walking long transects on volcanoes and landscapes where I was sure no one could have ever walked before, stories of flying toward erupting volcanoes, standing at the rim of a volcano, looking down into the smelly guts of the crater but I think you are asking about volcanoes, not experiences so I will give this a whirl.

The 1912 eruption of Katmai (Novarupta vent) was the largest eruption in world in the 20th century and it occurred in Alaska. This volcano is on the Alaska Peninsula, home to the Aleut native peoples and at the time, Russian settlers were the only white people. During this large, catastrophic eruption I had always assumed that any people in the area would have been killed by the massive pyroclastic flows and thick ash fall but in fact there are no reports of deaths (not recorded anyway). A few years ago I had the opportunity to go to Perryville, AK, a small native village south of Katmai. I was to talk to these people about a very large volcano in their back yard called Veniaminof. Before I went, I did a little research so that I understood who the people were a bit and I learned that were the ancestors of the Katmai refuges, those people that fled the Katmai valley during the great 1912 eruption. These people travelled by boat under a Russian captain, Perry to the current location of Perryville where they founded the village and have remained to this day. The displaced Aleut people made there new home at the base of what is considered the largest volcano on the Alaska Peninsula and Aleutian Islands…ironic. Anyway it was a real treat to get to meet these people and talk to them about hazards from Veniaminof Volcano. I held a town meeting in the school and hoped that many people would attend. I was most pleased when the oldest woman in the village attended (in addition to a large crowd) and I got to visit with her after my presentation. She was the daughter of one of the original Katmai refuges and her late husband was a small boy when the eruption occurred. She told me something that day that will stick with me forever. She shared with me that her mother always told her that Veniaminof Volcano was different, that there was no threat of ash (like there was during the Katmai eruption) but rather of water. I was shocked, amazed at the intuition of this old woman’s mother. Veniaminof Volcano is a gigantic caldera; many football fields across and totally filled with ice. What I had not shared with them that day (because we were still doing the research) was the remote possibility of catastrophic flooding by heating of the summit ice field by renewed volcanic activity. How could this woman have known of this such hazard (melting of ice field = water = flooding). These people have never seen the summit of this volcano; they had no idea that the summit caldera was filled with ice (a glacier) yet they understand the greatest hazard from future large eruptions of this volcano. Those people, that volcano will always be special to me.

We have a web camera hooked up in this village looking up at Veniaminof (there is a small cinder cone in the summit ice field that is frequently active); have a look if you are interested and if you are lucky it won’t be cloudy.

posted on Sat, 11/10/2007 - 2:54pm
kirsten's picture
kirsten says:

What is a caldera?

posted on Fri, 11/09/2007 - 11:22am
Kristi Wallace's picture
Kristi Wallace says:

I believe the word comes from the Spanish word for “cauldron” which is a good descriptive term for this volcanic feature. A caldera is a large (miles across) depression formed by collapse of the ground surface after a very large eruption (the largest, most explosive kinds of eruptions); they can look like impact craters. Basically the large amount of magma that is ejected during the eruption leaves a void space beneath the volcano so it collapses in to fill that void space and a large cauldron or depression is formed. Some calderas are more than 25 kilometers (15 miles) in diameter and several kilometers (~2 miles) deep. Calderas are among the most spectacular and active volcanic features on Earth. Earthquakes, ground cracks, uplift or subsidence of the ground, and thermal activity such as hot springs, geysers, and boiling mud pots are common at many calderas. I sort of think of caldera-forming eruptions (eruptions that form calderas) as the largest eruption that volcano will ever have and most likely it will only happen once in the life of that volcano (although I have worked on a few caldera systems that have evidence for multiple caldera eruptions-yikes). After caldera -forming eruptions occur, post-caldera activity is generally very different (less explosive) and new small volcanic cones often form inside the caldera walls but present a much smaller hazard. A couple examples of calderas in the U.S. include Yellowstone in Wyoming, Long Valley in California, Crater Lake in Oregon (this one is filled with water), and Veniaminof, Okmok, Fisher in Alaska. There are far fewer caldera volcanoes in the world than any other kind of volcano. I am particularly interested in calderas because I study volcanic ash and these volcanoes produce that largest ash deposits so in the field I see deposits from these large eruptions exposed in river cuts for example and when I do and if I know the age of the eruption, I know exactly where I am in time which is important in my line of work. These are my favorite types of volcanoes! Here is a photo of me inside the caldera of Veniaminof caldera in Alaska. The erupting cone in the background is a post-caldera vent. This caldera is filled with ice and snow and I am collecting ash from the erupting vent. http://www.avo.alaska.edu/image.php?id=3281

posted on Sat, 11/17/2007 - 1:15pm
Christina's picture
Christina says:

How do volcanoes form? How long does it take for them to form?

posted on Fri, 11/09/2007 - 6:12pm
Kristi Wallace's picture
Kristi Wallace says:

Volcanoes form when molten material (magma) from the earth’s mantle rises and erupts onto the surface. Magma rising from the mantle often collects in reservoirs called magma chambers. Eventually (but not always) enough magma accumulates and an eruption occurs. Layers and layers of lava flows form the main structure of a volcano and for volcanoes with more explosive activity, fragmental debris (shattered rocks) form additional layers to shape of a volcano. Some volcanoes form over thousands of years while others form in what seems to be a matter of days. I suppose it depends on when you start counting (is it when the magma starts to rise to the surface or is it the time it takes for a single eruption to occur and form the first layers of a volcano) to determine how long it takes to build a volcano. For perspective, we monitor our active volcanoes in Alaska and in May of 2005 our seismologists (those who study earthquakes caused by magma movement) starting noticing what they interpreted as a rise of magma under Augustine Volcano and in January of 2006, the volcano erupted. So it took about 7 months for the magma to rise from its mantle source to the surface and erupt.

posted on Sat, 11/17/2007 - 1:36pm
pyroclasticdoom's picture
pyroclasticdoom says:

How much do the gases relased from volcanic eruptions contribute to Global Warming?

posted on Fri, 11/09/2007 - 7:18pm
Kristi Wallace's picture
Kristi Wallace says:

This is a good questions and I don’t think we know entirely since this would require doing gas studies all volcanoes which is not happening so much of the data on this topic is extrapolated from well studied systems. Water vapor constitutes 70 to 95 percent of all eruption gases. The rest consists of carbon dioxide, sulfur dioxide and traces of nitrogen, hydrogen, carbon monoxide, sulfur, argon, chlorine and fluorine. The problem is complex because volcanoes can help cool the earth's surface by forming sulfuric acid aerosols that reflect the sun's rays, and also contribute to global warming by giving off carbon dioxide into the atmosphere, which contributes to the greenhouse effect. There is some evidence that volcanic eruptions can affect short-term weather patterns, and possibly trigger long-term climatic change. Carbon dioxide is abundant in volcanic gases, but not enough to significantly contribute to the greenhouse effect. From what I could find, volcanoes contribute about 110 million tons of carbon dioxide per year while man's activities contribute about 10 billion tons per year. My colleagues at the U.S. Geological Survey are studying volcanic emissions and global change through their Volcanic Emissions Project; I recommend checking out their progress on their website: http://vulcan.wr.usgs.gov/Projects/Emissions/

posted on Sat, 11/17/2007 - 2:15pm
Joseph's picture
Joseph says:

How does a volcano erupt under water?

posted on Sat, 11/10/2007 - 1:27pm
Kristi Wallace's picture
Kristi Wallace says:

Well there is really no difference between a volcano erupting underwater or on land. The over pressure of the water column is no big deal to the amount of energy inside an active volcano. Volcanoes are mainly found at plate boundaries and these places on our earth are both terrestrial and underwater and volcanic processes go on regardless. In fact, the most voluminous volcanic activity on earth occurs underwater at spreading centers where two earth plates are pulling apart and allowing magma to come to the surface quite easily. Huge chains of volcanoes form along these spreading centers. The two largest volcanic chains are along the East Pacific Rise and the Mid Atlantic Ridge. Iceland is where the Mid Atlantic Ridge comes to the surface and it entirely volcanic. I hope this helps but if you have a more specific question regarding submarine volcanism fire it my way.

posted on Sat, 11/17/2007 - 1:56pm
chickenwings's picture
chickenwings says:

How hot does it have to get for rocks to turn into liquid?

posted on Sat, 11/10/2007 - 6:06pm
Kristi Wallace's picture
Kristi Wallace says:

Can I go about this backward because I tend to think of molten material (magma) becoming a rock instead of the other way around. Magma comes from deep within the earth (in the Mantle) so it starts out as a liquid. By the time magma erupts through a volcanic vent (now it’s called lava) it’s temperature (still liquid or molten) really depends on the composition (the elements in the molten material and water content) so lava that has not changed much (compositionally) since it left the mantle is about 1200 degrees centigrade but magmas that incorporate other materials on their way up to the surface or have considerable water content (water lowers the melting point) tend to produce lower temperature lavas, 1000 – 1100 degrees centigrade. So basically, basaltic lavas like in Hawaii tend to be hotter while dacite and rhyolite composition lavas from strato-volcanoes like Mount St. Helens (WA) or Redoubt (AK) tend to be cooler by a couple hundred degrees centigrade. So to go the other way around, that is, to melt a rock depends on the rock type. It will take more heat to melt a basaltic rock then it will to melt a rhyolitic rock (these two rock types are on opposite ends of the composition spectrum). I work with colleagues who do this type of research, melt rocks in furnaces and adjust the pressures and temperatures to see what happens, for example, what minerals form etc. Pretty cool stuff!

posted on Fri, 11/16/2007 - 7:01pm
Anonymous's picture
Anonymous says:

will mount st. helens erupt like it did in 1980 again? what about vesuvius?

posted on Tue, 11/13/2007 - 12:43pm
Kristi Wallace's picture
Kristi Wallace says:

Mount St. Helens will certainly erupt again in the future (in fact, it is in eruption status now) but we cannot say for certain if it will have another 1980-like eruption. The 1980 eruption was smaller in fact than those of several earlier eruptions of Mount St. Helens. Since May 18, 1980, Mount St. Helens has remained intermittently active, and through the early 1990 at least 21 more periods of eruptive activity had occurred although none have been as large as the 1980 eruption.

It should be noted however, that our ability to predict when an eruption might take place has greatly improved since the 1980 eruption. We often have lead times of months to day. Since 1980, all episodes (except for one very small event in 1984) have been successfully predicted several days to 3 weeks in advance. Even for accurately predicted eruptions, however, there is no way to anticipate their size or duration. Scientists are not yet able to forecast accurately the long-term future behavior of volcanoes. The best evidence for the size of future eruptions is to look at its past eruptive history. The most recent and best known of the pre-1980 eruptive periods began with a major explosive eruption in 1800 A.D. For the next 57 years, this event was followed by intermittent relatively small explosive eruptions, lava flows, and the extrusion of a lava dome. Assuming that Mount St. Helens behaves as it did in the 19th century, the present activity could continue intermittently for years, possibly decades. Such activity could include the outpouring of lava flows (not observed to date), as well as renewed dome growth and small-to-moderate explosive events. The chance of another catastrophic landslide and blast comparable to that of May 18, 1980, is exceedingly low. The past history of the volcano suggests, however, that one or more explosive eruptions with heavy ash fall comparable to that of the May 18, 1980, eruption might occur before Mount St. Helens returns to a dormant state. This history of intermittent activity is one of the most important reasons why my colleagues at the Cascades Volcano Observatory continue to monitor the volcano.

posted on Mon, 11/26/2007 - 1:18am
Anonymous's picture
Anonymous says:

Can you go inside a volcano? Have you ever done that?

posted on Tue, 11/20/2007 - 1:51pm
Kristi Wallace's picture
Kristi Wallace says:

By “inside a volcano” I assume you are referring to going inside a volcanic crater, if so then, YES you can go inside a crater so long as it is not active when you visit. Many dormant volcanoes have well-formed craters that are safe to walk inside but it is always a good idea to check with the volcano observatory responsible to studying a volcano before you go. Lots of people for example, visit Crater Lake in Oregon which is a lake filled volcanic crater that is no longer active. YES, I have been inside a few volcanic craters, some, I have only stood at the rim. For the most part however, we don’t hang out inside volcanic craters because the volcanoes we are interested in are active and that would not be safe, mostly because of exposure to toxic gases.

posted on Mon, 11/26/2007 - 1:32am
Anonymous's picture
Anonymous says:

What's a cinder cone volcano? They have a picture here of one that formed in someone's field in Mexico.

posted on Tue, 11/20/2007 - 1:52pm
Kristi Wallace's picture
Kristi Wallace says:

Oh yes, I think you are referring to Paricutin, a cinder cone that grew out of a corn field in Mexico in 1943. This is probably the most famous cinder cone because of the cool story associated with its origin.

A cinder cone is a steep, conical hill of volcanic fragments that accumulate around and downwind from a vent. The rock fragments, often called cinders or scoria, are glassy and contain numerous gas bubbles "frozen" into place as magma exploded into the air and then cooled quickly. Cinder cones range in size from tens to hundreds of meters tall.
Cinder cones usually erupt lava flows, either through a breach on one side of the crater or from a vent located on a flank. Lava rarely erupt from the top (except as a fountain) because the loose, non cemented cinders are too weak to support the pressure exerted by molten rock as it rises toward the surface through the central vent. Cinder cones are commonly found on the flanks of shield volcanoes, strato-volcanoes, and calderas. For example, geologists have identified nearly 100 cinder cones on the flanks of Mauna Kea, a shield volcano located on the Island of Hawaii (these cones are also referred to as scoria cones and cinder and spatter cones).

posted on Mon, 11/26/2007 - 1:39am
Anonymous's picture
Anonymous says:

Did the eruption of Santorini and the city there start the legend of Atlantis?

posted on Tue, 11/20/2007 - 1:54pm
Kristi Wallace's picture
Kristi Wallace says:

Whatever and wherever Atlantis was, if such a place really once existed, we probably will never know for sure. However, there are a number of clues to be found in Plato's story that make many people believe that the destructive Minoan eruption on Santorini is the most likely candidate for being the historic fact behind the story. Of course as a volcanologist, I favor this explanation. In graduate school I had a professor that was just as much a philosopher as a geologist and in his teachings he combined human culture and volcanic events so to be honest, I visualize the lost city of Atlantis sinking as a result of a natural processes of caldera formation but really I have not done a lot of thinking on the topic. I thank you for sparking my interest again!

posted on Mon, 11/26/2007 - 2:26am
Daniel S.'s picture
Daniel S. says:

How can you tell a dormant volcano from an extinct one? And how do you predict eruptions?

posted on Wed, 11/21/2007 - 12:47pm
Kristi Wallace's picture
Kristi Wallace says:

We will start with some accepted definitions:

1) Dormant Volcano: The term is used to describe a volcano which is presently inactive but which may erupt again. An active volcano might be erupting or dormant. An active volcano is a volcano that has had at least one eruption during the past 10,000 years.

2) Extinct Volcano: A volcano that is not presently erupting and is not likely to do so for a very long time in the future. An extinct volcano has not had an eruption for at least 10,000 years and is not expected to erupt again in a comparable time scale of the future.

So in order to tell the difference, we must first know something about the eruptive history of a volcano. The shape of the volcano may also help to distinguish between dormant and extinct volcanoes because old eroded volcanoes are tell tale signs that eruptive activity has not occurred for a very long time and that erosion is the major force acting to shape the volcano (rather than eruptions).

Predicting Eruptions:
Regarding prediction of eruptions, we have come a very long ways in this science. As magma moves beneath a volcano prior to an eruption, it often generates earthquakes, causes the surface of the volcano to swell, and causes the amount of gases emitted by the volcano to increase. By monitoring these changes, we are often able to anticipate eruptive activity and issue warnings of possible hazards. While not all of these changes are observed before every eruption, combining observations of each of these precursors often allows scientists to forecast eruptions.

Often the first indication of an impending eruption is an increase in earthquake activity. Generally, a network of six to eight seismometers are positioned around a volcano. Readings from each seismometer are used to determine the locations, sizes, numbers, and types of earthquakes. In the weeks or days prior to an eruption the number, size and type of earthquakes that occur beneath the volcano will often increase. In many cases, the earthquakes will move to progressively shallower depths beneath the volcanic vent.

As magma moves to shallower depths it can cause the surface of the volcano to swell. Scientists monitor the deformation of the ground surface using a variety of surveying techniques and instruments.

As magma nears the ground's surface it releases several types of gas. These include water (steam), carbon dioxide, and sulfur dioxide. Significantly increased gas emissions from a volcano may indicate that it is about to erupt.

posted on Mon, 11/26/2007 - 2:14am