Mount Shasta or Úytaahkoo, the “White Mountain”

Fig 1. Sunrise at Mount Shasta with the satellite cone Shastina to the left  (Wikimedia Commons).

Fig 1. Sunrise at Mount Shasta with the satellite cone Shastina to the left (Wikimedia Commons).

Volcanic activity in North America is surprisingly infrequent. In spite of there being no less than 255 volcanoes or volcanic features such as maars or volcanic fields listed for California (20), Oregon (65), Washington (21) and British Columbia (149), situated on or adjacent to the Cascades Range and above the subduction zone where the last dregs of the Farallon Plate is disappearing beneath the main continent and the Juan de Fuca plate knocking on the door, there have only been some 20 eruptions or periods of eruptive activity over the past 1,000 years. This is a surprisingly low number for the Ring of Fire and if we compare with Alaska, Japan, the Philippines or Indonesia, we can only surmise that the entire Cascadian Arc with its associated volcanic fields is in a quiescent phase.

Located at the southern end of the Cascade Range in Siskiyou County, California, the 4,322 metres high (14,179 ft) Mount Shasta is ranked as the second highest peak of the Cascade Range after Mount Rainier. It rises 2,994 metres (9,822 ft) above the surrounding landscape and has an estimated volume in excess of 350 km3 (85 cubic miles) which makes it the largest of all Cascade volcanoes, ahead of the similarly sized Mount Adams and the imposing Mount Rainier which towers above Seattle. It is mainly composed of silicic andesite to dacite.

Figure 2. Shasta, Shastina and in the foreground, Black Butte, tiny in comparison in spite of rising more than 600 m above the surrounding landscape itself. (

Figure 2. Shasta, Shastina and in the foreground, Black Butte, tiny in comparison in spite of rising more than 600 m above the surrounding landscape itself. (

Mount Shasta is composed of four overlapping cones, five if you count the destroyed cone of ancestral Shasta, which together form the main peak Shasta and the satellite cone Shastina. At 3,760 metres (12,330 ft), Shastina would rank fourth of the Cascade peaks if it were recognised as a separate mountain. Nearby is a 9,500 year old dacite lava dome associated with Mount Shasta, Black Butte. In it’s own right, it could be considered to be a large mountain as it rises more than 600 metres above the plain to the NNW of Shasta, even if it is dwarfed into insignificance by Shasta and Shastina in the background.

Fig 3. Mount Shasta often experiences strange weather phenomena. Here, Shasta is hidden by clouds whereas the cone of Shastina is clearly visible. Visible also in the foreground is the remains of the absolutely massive debris avalanche dated to between 300 and 380 kA that resulted from the collapse and total destruction of the ancestral cone. (

Fig 3. Mount Shasta often experiences strange weather phenomena. Here, Shasta is hidden by clouds whereas the cone of Shastina is clearly visible. Visible also in the foreground is the remains of the absolutely massive debris avalanche dated to between 300 and 380 kA that resulted from the collapse and total destruction of the ancestral cone. (

Before we move on to have a look of the geological history of Shasta, it is worth noticing that because of the meteorological conditions, quite often a difference of 60C or more between the valley to the north and the mountain peak, Mount Shasta is often accompanied by strange cloud formations. Is it surprising then, located in California as she is, that she is a favourite with UFO-ologists with claims such as the one that there is a portal located on Mount Shasta from which alien spacecraft appear periodically…

Fig 4. The landscape left by the gigantic flank collapse and subsequent debris avalanche dated to between 300 and 380 kA. The peaks of Shasta and Shastina tower above the landscape and to the right Black Butte right at the foothills of Shasta is clearly visible. (John Scurlock,

Fig 4. The landscape left by the gigantic flank collapse and subsequent debris avalanche dated to between 300 and 380 kA. The peaks of Shasta and Shastina tower above the landscape and to the right Black Butte right at the foothills of Shasta is clearly visible. (John Scurlock,

Even if there is evidence of much earlier volcanism in the area, activity at Mount Shasta is thought to have begun about 590,000 years ago and is divided into four distinct periods. The first cycle, which lasted about a quarter of a million years, saw the building of the ancestral cone from mainly andesitic lavas and ended with its destruction somewhere between 300 and 380 thousand years ago. The cone of ancestral Shasta was almost completely destroyed by a sector collapse of truly epic proportions. The total volume of the collapsed sector is estimated at 45 km3 and covers an area of about 675 square kilometres with a maximum extent of 49 kilometres to the north. Some of the “boulders” carried down by the avalanche still protrude more than 100 metres in height above the avalanche deposit floor… As a comparison, the debris avalanche from the 1980 sector collapse of Mount St Helens had a total volume of about 2.5 km3 and reached 23 km down a river valley. There is no evidence of contemporary volcanic activity, thus the cause of the avalanche remains unknown.

Fig 5. Shasta’s peaks: SR – Sargents Ridge 250kA, MH – Misery Hill 130 kA, Sh – Shastina 9.5 kA. The current summit, the Hotlum cone is younger than Shastina. (

Fig 5. Shasta’s peaks: SR – Sargents Ridge 250kA, MH – Misery Hill 130 kA, Sh – Shastina 9.5 kA. The current summit, the Hotlum cone is younger than Shastina. (

After the sector collapse that destroyed ancestral Shasta, there seems to have been a hiatus of between 50 to 130 thousand years after which the oldest of the four cones that make up modern Shasta, the Sargents Ridge cone, began to grow less than a quarter of a million years ago. What remains today of this cone that has undergone two periods of glaciation is visble on the south side of the mountain. What today is the main edifice of Shasta, the Misery Hill cone began to grow about 130, 000 years ago and has suffered one period of glaciation. The final two cones are both Holocene. The truly massive satellite cone Shastina was formed over a period of merely 300 years between 9,700 and 9,400 years ago while the present summit, the Hotlum cone is younger even if it may overlap Shastina in age. A small craterlike depression in the summit dome contains several small groups of fumaroles and an acidic hot spring. The extrusion of these domes was accompanied by pyroclastic flows which extended more than 10 kilometers south and 5 kilometers north of the domes.

Fig 6. “Mount Shastina”. As is clearly visible from this picture, Shastina is a highly impressive volcano in its own right. Notable is that it grew in an incredibly short period of time, 300 years, just under 10,000 years ago. (

Fig 6. “Mount Shastina”. As is clearly visible from this picture, Shastina is a highly impressive volcano in its own right. Notable is that it grew in an incredibly short period of time, 300 years, just under 10,000 years ago. (

Shastina is a stratovolcano composed of silicic andesite flows and dacite plugs and has a topographic prominence of over 137 metres (450 ft) as measured from the saddle that connects it with Shasta. This easily exceeds the typical mountaineering standard (91 metres or 300 ft) for a peak to qualify as an independent summit, yet for some peculiar reason, this is not applied. As Shastina towers at 2432 metres (7979 ft) above the surrounding landscape, I personally feel that Shastina is hard done by. In comparison, Vesuvius is no more than a 1,281 metres high midget of a volcano.

Fig 7. The impressive dacite lava dome complex Black Butte as seen from Interstate 5. Anyone fancy a ride? (

Fig 7. The impressive dacite lava dome complex Black Butte as seen from Interstate 5. Anyone fancy a ride? (

The final major feature of the Shasta complex is the parasitic dacite cone complex that makes up the 600 metres high Black Butte, 13 km northwest of Shasta. It was formed right at the end of the period of activity that created Shastina and the Hotlum Cone some 9½ thousand years ago.

Over the last 10,000 years, Shasta has erupted on average once every 800 years. The most recent eruption at the Hotlum cone, the present summit of Shasta proper, may have occurred as late as 1786 A.D. The eruptions appear to have been small, something that cannot be said for the eruptive period of c. 9,500 years ago – andesitic lava flows, dacitic lava dome extrusions accompanied by large pyroclastic flows that reached up to 20 km from the volcano and formed the massive Shastina, the current summit complex and Black Butte.


Suggested further reading:

Shasta geology –

Shasta volcanic hazards –

Black Butte –


207 thoughts on “Mount Shasta or Úytaahkoo, the “White Mountain”

  1. Shasta has a lot of similarities with Popocatepetl, although it doesn’t seem quite as active as Popo has been recently. Black Butte is quite stunning – Californians really do live in an incredibly beautiful state, between the Sierra Nevada, Napa, Yosemite, Tahoe, the California coastline, and other places such as Shasta.

    If I had a guess, I would say that the lull in volcanic activity in the cascade arc is probably related to the slow subduction rate. The cascade subduction zone I believe is one of the slowest in the world, which would mean that there is less “fresh” oceanic crust dipping into the zone that causes melt. Less crust subducting means less magma, which could explain why the cascades seem less active than other major volcanic arcs around the world. It’s also a much smaller arc than what you see in Japan, Indonesia, or the Andes.

    Also, does that eruption rate account for the Aleutian arc? The Aleutians have been highly active over the last 10,000 years, and are probably comparable to any of the large volcanic arcs around the world. I would think many eruptions in the Aleutians in the past 10,000 years are relatively unknown due to the difficult of studying them and the remoteness of the region.

    My final comment, is that since writing the post on Popocatepetl, I’ve had a growing interest in massive flank collapses at Volcanoes. Flank collapses like the massive collapse events at Shasta and Popocatepetl seem like they would be no less devastating than a caldera forming eruption, and the area affected in such events is truly massive (and far reaching). We’ve also never seen a large-scale flank collapse in historical times, with the only collapse events being limited to St. Helens and Shiveluch, which were miniscule in comparison to the collapse events seen at volcanoes that are extremely large.

    • The cascadian arc is of a different type in comparison with the Aleutian arc. The cascadian is mainly moving alongside the US continent, something that can be seen at for instance the San Andreas fault.
      The Aleutian on the other hand is a true subducting arc, and then we have the Alaskan bend that is causin rather interesting phenomenon on it’s own.
      The Aleutian arc is definitly one of the most active on the planet.

        • It is just my own silly word for the “bendy” area where the fault shifts direction from following the US western coastline and bend into a westerly direction out over the Aleutian Arc. Kind of the Arch-Arc of the US.
          Look at google earth for Alaska and you will see the Bend. Around it you have Churchill in one end and Katmai about the other end of the bend.

          There is a long and complicated scientific word for it, but I have forgotten it. Que someone with better memory! 🙂

    • This could be said for any volcano realistically. If we’re going off historical probability (which isn’t that reliable) Shasta probaby won’t erupt for another 400 or so years, assuming the 1700’s eruption wasn’t just a phreatic detonation.

          • Lassen Peak isn’t really a volcano, at least it’s not the central volcano. It’s a dacite volcanic plug or dome, one of the largest in the world. And yes, Lassen, or rather the central volcano, is a good candidate for an eruption within the next thousand or ten thousand years. 😉

            • Wouldn’t that qualify it as a volcano, or at least a volcanic complex then?

              Lassen is quite a strange volcano / volcanic area. I know Erik Klemetti has done a lot of research on it – I’d be interested in learning more about it’s eruptive history and such. It strikes me as the type of volcano that could form a huge eruption given due time (although that’s just a guess).

        • The siskeyous website explains that Shasta did not erupt and that it was a misinterpretated fire. These probably was an eruption in that time, it just was not observed.

          • Where? From the website:”Growth of the summit dome was followed, perhaps no more than 200 years ago, by explosions that blasted out its central part and produced an eruption cloud that spread gray lithic tephra widely across the northern flank of the mountain”.

  2. From the Sisikyous website:

    “Black Butte, a complex of hornblende dacite domes that stands next to Interstate 5 between Mount Shasta City and Weed, formed during a late phase of the Shastina episode. It grew in four distinct pulses from a crater that had opened about 12 kilometers west of Shastina (Figure 22). A detailed study of dacites from Black Butte (Katz, 1997) suggests that all of the domes were fed from the same reservoir, and that the ascent of each batch of magma continued without pause for at least 8 days once it had begun. RADIOCARBON DATING indicates that the entire Shastina eruptive episode lasted no more than a few hundred years “

    • Like I said in the article, the Hotlum Cone, Shastina and Black Butte were emplaced more or less simultaneously in probably under 300 years. Wouldn’t you want to see that rather than a nasty flank collapse!

        • I would. A flank collapse can be non-volcanic, and that happened at Shasta. Its magma chamber has evolved for quite a while, and it has erupted only small volumes of magma throughout its history. CalVo lists this tidbit.

          “The Mount Shasta magmatic system has evolved more or less continuously for at least 590,000 years, but the ancestral cone was virtually destroyed by an enormous volcanic sector collapse and landslide around 300,000 years ago.” The words before the comma are very important. Even more interesting is this:

          “It has been suggested that because it is a long-lived volcanic center and has erupted only relatively small volumes of magma for several thousand years, Mount Shasta is the most likely Cascade Range volcano to produce an explosive eruption of very large volume. Such an event could produce tephra deposits as extensive and as thick as the Mazama ash and pyroclastic flows that could reach more than 50 km (30 mi) from the vent. The annual probability for such a large event may be no greater than 10-5, but it is finite.”

  3. Earlier today Lurking mentioned that Toulose VAAC is doing a lot of Grimsvötn eruption simulations. And previously London VAAC did a lot of Hekla (haven’t checked what they love right now though).
    At the same time in Iceland they like Katla, Grimsvötn and Askja.
    Here is their latest Katla run.

    Please note, this is just a practice run done so that if anything happen people would know where it would go. No eruption is ongoing at all, especially not at Thingmúli.
    Image and video hosting by TinyPic

      • Yepp, I call that pattern for a Laki run, since it is the path the Laki ash took.
        It is also roughly how the Eyjafjallajökull ash went in the beginning.

        • Its not a joke.

          Both Hekla 1104 and Oraefajokull 1362 had VEI5 eruptions very near the VEI6 threshold, around 10 km3. At least from what I heard from Icelandic sources at Skaftafell national park.

          Such a plume would easily go 30km high. Grimsvotn went 23km in first couple of years.

          • Nope not a joke at all. They want to be sure to have it covered even if Hekla went beyond what it has done lately. One should remember that Hekla have done larger eruptions than the 1104.
            And Grimsvötn 2011 proved once and for all that the Meme that a volcano need a long repose to erupt big is patently false in Iceland when it did it’s largest eruption after a period of very frequent eruptions.

            I am though not in any way saying that I think a Hekla VEI-6 is likely.

      • Ho! 30 km plume initially but reduced to 10 km a few hours later (6 – 10 hrs?). VEI 5, maybe bordering on VEI 6 then. Some simulation, thanks Tyler!

        • London VAAC like large simulations. Somewhere I have a VEI-6 3 hour long eruption at 45 km they did for Hekla. Either they where bored, or someone had nightmares.

  4. thanks Henrik that was a great post. I’ve been bounced and beaten around by Cascade mountain waves more than
    i want to think about. A number of years ago someone attempted a Sailplane altltiude record out of Montague.
    they got to FL450 above shasta and had an O2 failure did get back but had one wild ride as they went back though
    the Lenticular and then the roll cloud.
    Also Intrerstate 5 in that area is no fun in the winter-mountain country lots of snow…

    • Did you ever fly close by Shasta T.G? I’m curious as to how it looks from above but not Space Shuttle high, if you see what I mean.

      • Many times- when I was based in Medford, Or I worked a fire near McCloud, never got above the 3000 meter line on that one but flew close to Shastina and over Black Butte. I’d like to know how they were close in origins, whether or
        or not they erupted at the same time according to theroy… Shastina’s got quite a crater at the top…
        Montague had a reload base for fire ops..One of the local Calfire guys was known as “Bigfoot” given the local
        lore (Lemurians,aliens and Sasquatch, ) I always wondered about him. Could single hand a reload hose and pick up
        a bag of retardant mix at the same time… what are are Lemurians-?: Some (highly suspect) geology and anthropology here. But if you spend time in Northern Ca. Southern Oregon Lemurians are a small industry around Shasta….

        Kind of like ” Nessie” in Loch Ness…

        • Thanks! It does look that way from the photos which is why Shastina is the best candidate as the origin of those huge pyroclastics mentioned in connection with the active period ~10 kA.

  5. Is Mount Shasta also capable of producing V.E.I. 6 eruptions? Any idea how big its magma chamber is? I see in any volcano related to subduction a potential V.E.I. 6 beast.

  6. Great post. Enjoyed reading it.

    OT: But we had a family emergency yesterday. My dad fell while getting onto our roof from the ladder. It was about an 8 foot drop onto our deck. He’s in the hospital right now and he broke about 5 of his ribs. And i was there holding the ladder for him when it happened, so I’m kinda traumatized by this whole thing. They thought he had some internal bleeding, but that wasn’t the case. I’ll keep you guys up to date.

    • Ouch, breaking ribs hurt a lot. Worst part is sleeping, and after a few days you normally start to cough… and that hurts like you wouldn’t believe.
      Don’t worry to much Tyler, crap like that happens, although it is not fun.

    • Oh, Tyler, your poor dad. Broken ribs are so painful. Wishing a speedy recovery to Dad and sending a hug for you.

    • Scared the ever loving shit out of you I imagine.

      When I lost my dad it tore me up mentally for a few years. By the time I got my head back on straight I had almost completed my first tour in the military. I wound up there because it was the quickest way to make something of myself. Something my dad would have been proud of.

      Best wishes for you and your dad, and here’s to a speedy recovery.

      Here I am 20+ years later, and I just ‘got out of prison’ for the 3rd time in two days. I don’t like going there, there are criminals all over the place, but it pays well. The bane of doing field service work… sometimes you wind up in a prison. 😀

        • That panic attack feeling is when you have the intense motivation to do something, but you don’t know what… or you can’t act on it in a way that you feel you need to.

          Several years later, I was visiting my Mom at my Granddad’s house. (R.I.P.) and the weather grew nasty. Listening to the weather alerts and doing distance and orientation calcs in my head from the spotting reports, I became aware of a funnel cloud nine miles south and nine miles west of where I was at. Around here, the dominant direction of travel for tornadoes is NE. Since I was at a bearing of 45° from the tornado I became quite alarmed. I went out to the front porch where the lightening was so intense that you could have read a newspaper from the light. The sky was that lit up. Except… there was one spot to the SW where there was almost no lightning. A big dark hole in the flashes of light… and it was getting bigger. I ran back in side and threw the couches up against the wall and ordered… not asked, ORDERED my mom and wife behind them and threw blankets and pillows over them. Then I thought about the age of the house and the tube and post wiring in the attic. I didn’t know if all those old circuits had been bypassed and replaced, or if any of them were still hot, so I threw the main breakers and took cover with my mom and wife. The 150 year old pecan tree went bye bye, and the swing on the front porch came in through the front window…. then half the roof went away. I wasn’t sure how it was going to turn out when the floor started jumping up and down, but it passed and things quieted down. My aunt, who had ownership of the house had insurance, and that covered the repairs. To my amazement, the debris from the roof missed my truck and landed next to it. That’s about all that I can remember from that evening… but had I not kept my head, panic could have killed me.

          With a medical situation, we don’t always know what the best course of action is… and we don’t know how bad an injury is. We freak out. It’s what we are wired to do. The way you deal with it is to gain as much knowledge as you can, and think it through ahead of time. I never considered the propane tank behind the house to be much of a hazard… had the tornado gotten ahold of it, it would have ripped it from the piping and thrown it clear.

          Just an FYI…. not trying to be morbid or anything. If something happens to your dad, you may wind up in probate court in order to settle his estate. If he is married, it all falls upon his wife by default. One thing to pay attention to, in that event, is the tax roll. Don’t let the county jerk you around and not send the tax bill to the correct address. If it falls in arrears, they will auction off the debt and then the company that buys it up can add a crapload of interest and other charges in order to forgive the debt. If it gets high enough , they will file with the court for ownership and have the property free and clear with no renumeration to you. Essentially, legally stealing the house. I got screwed over like that because I was deployed and was unable (and unaware) of what was going on. I bit and paid off the inflated charges plus what the company had bid for the property, but the county never corrected the mailing addresses. Managed to loose a nice chunk of money and the property in the process.

          Yet another reason for me to not return to the literal shit-hole of Jackson Mississippi. I really hope that 81 million year old volcano wakes up.

          • Public Servants are in reality Public Masters and Public Thieves. The US Constitution allows ordinary people to own and carry guns just for such a contingency.

          • Which is why they do not wish for us to be armed.

            In any scam, it’s just a matter of time before the mark realizes that they have been taken advantage of. The last thing those criminals want is for the victims of their crimes to come to that realization while still retaining the ability to take corrective action.

      • You wind up some more interesting places than prison sometimes.

        I used to be Dell’s senior field guy in the UK.

        I worked on servers built in to safes at police Special Branch locations, and was inside GCHQ a couple of times… yes it involved destroying hard drives!

        • I heard that they recently wanted to destroy some files but did not really understand the concept behind the Google-cloud… And why they could not go to both Finland and the US and whack harddrives at their hearts content. I do not understand why you UKians stand for it. I know you have guns for Grouse-hunting. 😉

        • I have a couple of sites that have placed their server and communications racks inside of ex-bank safes. The one in Crestview has one of the more beautiful high end Panduit cable management set ups around. The only one that beats that is in Panama City. They gave the whole farm it’s own office. There is one small desk in the corner near the door that they stuck one of their clerks at. Noisy as hell, but at least she has a small window and can look out on the floor at the other clerks and customers.

          But.. government is government. Stupidity reigns supreme. Another county has one of the nodes for their SAN located in a facility one mile from the beach, 3 feet above sea level.

  7. And here are something for the SPAM munching Dragons to lift their spirits.
    Something that is sorely needed after 2 days of spam-attacks non stop from a Chinese spam-bot net…

  8. Many years in the past I had the “pleasure” of having C Rats for a extended period,the kitchens on the Forestal CVA59 had a major electrical failure so the meals ended up being C Rats from the korean war this was in the early 70’s a tin of spam and other things tinned for long term storage. I ended up hating spam for many years eventually we figured out that C Rats were in fact canned rats. Now the field meal is called a MRE translated it is Mostly Rat Excrement, better than tinned rats but not real food

    • We don’t have a point or “like” system here, but I give this three thumbs up.

      … actually, we do have a point system for the weekend riddles. I have only gotten one official point… for identifying a magma before the question was asked. Go figure.

  9. Before I do anything else, a big thank you to all the people who liked the article! It was fun writing it. Now, quite a few people have asked “what” can she do? Outside the article, I can give you my personal and amateur view.

    First of all comes the risk of a sector collapse. As with many other Cascade volcanoes, Shasta is rich in volcanic gases of the rock-transforming kind (sulphur compounds). Given enough time, a couple of hundred thousand years or so, they can transform enough of the mountain core from rock to clay. With such a large edifice, the pressure on the weight-bearing layers is enormous and should they fail, the debris avalanche will be correspondingly massive. It has happened at Shasta before. It has happened to several nearby volcanoes as well. It should be regarded as a real risk, but as Misery Hill cone (which forms the bulk of Shasta’s edifice) “only” is about 130,000 years old, such a collapse could be well in the future.

    Secondly. As the most recent major eruptive period ~10 kA was mainly effusive, it is unlikely that the magmas in her magmatic system are so rich in volcanic gasses that a major explosive eruption is likely, even if 10,000 years is plenty to fill up her magma reservoirs.

    Thirdly. Why this fascination with 50 km3 sector collapse debris avalanches or Mazama-type very large edifice-destroying eruptions? Personally, to observe the birth of a huge volcano such as Shastina or lava domes as large as Black Butte within possibly the space of a few centuries for Shastina and possibly as little as a few years for Black Butte (to judge by other, similar features close by), is far more intriguing.

    • I agree – Black Butte is really quite interesting. I think the primary edifice must have been pretty plugged up if magma was being forced out where Black Butte and Shastina formed.

  10. About to attack Coffee # 3….. No ruminations. No time with the wedding just hours away. The comments about panic attacks rung a bell here although at this late stage nothing will surprise me and there’s not a lot now that can be done. I just hope the weather stays dry and settled.
    Tyler best wishes for a speedy recovery for your poor Dad. Just try not to make him laugh too much when he gets home. Laughing with broken ribs brings tears to the eyes.
    Henrik Thanks for this article. What beautiful mountains and fascinating histories.
    It’s a really good read and stunning pictures.
    Right…..Time for the off again …… I shall be relieved when it’s Sunday Morning!

    • Yepp I agree… I have tried the broken ribs concept.
      Do not make him laugh Tyler, be boring as hell. That is the nicest thing you can do, trust me. I can vividly remember the pain of just a small little giggle.

  11. A very nice article Henrick, and one that scratches an itch I’ve had for a while now.

    One thing that always struck me when browsing the late lamented old GVP site was just how much vulcanism in North America was characterised as “holocene, but more than 1000 years old”. Literally dozens of features with evidence of eruptive activity in the period since the last Ice Age, but in the last few hundred years there has been SFA activity of note in the lower 48 other than Lassen & St Helens.

    It appears that to me that, Alaska excepted, North America really is going through a low in volcanic activity. Whether this is a real effect or just observational bias / poor dating I cannot say.

    A thought – perhaps there was a period of enhanced activity ending a thousand or years ago either due to loss of ice loading after the Ice Age, or the final demise of the subducting Farallon plate.

    Just some (very) amateur musings, and probably wrong on several levels.

    • I’m of the same opinion as you are – volcanism in the USA tends to run in batches or periods where many volcanic centers are active “simultaneously” (within the same period of one or more millennia). I look forward to returning to this discussion with you after my next two articles have been published as there is a lot of data there that points in this direction.

      • Its actually a similar situation here in Australia, although driven by intraplate hotspot vulcanism rather than subduction. There’s volcanic features up & down the East Coast, and evidence of eruptions within the last 12000 years both in Far North Queensland and in South Western Victoria & South Eastern SA. There are even Aboriginal “dreaming” legends that HAVE to be volcanic eruptions, e.g. what appears to be a description of the formation of the Lake Eacham Maar on the Atherton Tableland some 12000 years ago.

        But since European settlement – nothing. Not even a fumarole. A few faint quakes beneath Mt Gambier, and a couple of sulphur rich hot springs near Undara, QLD, and that’s it. But everywhere you look there’s old flows, cinder cones, eroded plugs, pointing to a huge amount of volcanic activity in the last 20 million years.

        Hmm … maybe I should collate my sources and do an article or two on recent Australian vulcanism.

        • Me too!
          I know Jack the Smurf about Aussie volcanism.

          Regarding the volcanism in the US, I am rather fond of the concept of isostatic relief being the culprit. Same thing has happened all over the northern hemisphere, even in Iceland, wherever one looks the largest eruptions where from 10K years ago up to about 3K years. Ice is the only culprit that is common for all of the places.

            • I have quite a list of culprits.
              Only in Iceland, all plus 10 cubicers:
              Skjaldbreidur, Thjorsahraun, Hengill, Theistareykjarbunga, Prestahnukur, Krafla, Dyngjufjöll, Kistufell, Odhadhahraun, Brennisteinsfjöll, Fremirinamar, Katla, Vatnafjöll (several) plus about five more shields. And that is far from a complete list.
              Imagine fifty bigger than Laki going off in Iceland within 1000 years and you have a good portion of the sulphates there. Now add the North American Volcanoes, the New Zeeland, the Antarcitc ones… Ah, forgot Europe and Laacher See, and the southern South American ones… All near polar volcanoes on the planet went for a size record during that millenia. The entire planet must have stunk to high heavens.

            • As you probably know, what I’m referencing is this graphic from Lurking’s rumaniarian series.

              You definitely have to think it’s related to de-glaciation. 50 laki’s going off within 1000 years? Where from in Iceland? That’s pretty crazy sounding, but that definitely seems like it would be enough to cause those massive spikes that dwarf most other spikes in the last 6000 years.

            • I don’t think it was any antarctic volcano. In Canada, Iceland and the cascades, the glaciers were completely removed in some cases and in others they shrunk badly in both size and thickness. That allowed decompression to occur, and large amounts of magma were produced in a relatively quick amount of time. In Antarctica, the ice sheets retreated, but the volcanoes of the west Antarctica rift stayed quiet as usual during said time. Why? There was no large-scale removal of ice. Early Holocene activity happened only at Takahe and Berlin. Only Takahe had some eruptions later. If the ice was removed, more activity would likely occur.

            • I listed the volcanoes.
              During a span of one millenium all of the largest Icelandic eruptions happened. Thjorsahraun, Theistareykjarbunga, Skjaldbreidur, Odhadhahraun and Dungjufjöll had eruption that each was at least 3 times larger then Laki.
              As I said, the planet must have stunk a lot during that millenium. I wonder if that odiferous condition did not influence a lot of religions really… Imagine that the world in wave after wave quite literally stunk as Hell’s Gates where opened up.

            • Somewhere in the back of my head Erebus beccons. I think that she had a large one around then. But, I am not at all sure. Anyhow, Ice lifted both in New Zeeland and in the southern South America at the same time.

              You are most likely right in that the risk of increased volcanic activity will increase as glaciation diminishes over Antarctica.

            • When you analyse the historic record of Iceland – let’s say something simple like the ash layers in the soil sections of my backyard – you see a notorious presence of large eruptions in the millenia following the end of the ice age.
              As ice melts and pressure relieves, then eruption occur freely and to large extents. This early Holocene activity affected mostly volcanic fissures just where the ice has melted, not elsewhere.

              So, now, as ice melting is gaining speed again in Iceland, (and together with an expected hotspot maxima in soon), one should expect large eruptions just where glaciers have been retreating more heavily.

              I think: Langjokull (one of fastest retreating ice caps in Iceland), Katla and Eyjafjallajokull (this one already did it), Tindfjallajokull, Snaefellsjokull (another quickly disappearing glacier) and possibly Oraefajokull, Kverkfjoll, Esjufjoll and Hamarinn, all located at the edge of the ice caps.

              For instance, at the ice at Oraefajokull, the ice cap decreases around 1-2 meters in thickness and altitude, per each year. It sounds a bit but not much compared to the existing 300 meters of thickness.

              But that gives more 150-300 years of existence for that ice cap, and actually for most of Vatnajokull (which has a similar thickness), if the current rate prevails.

              Just imagine the volcanic BIG party at Iceland in the years following 2200, if the melting continues!

            • I don’t think Erebus pulled anything big. The biggest currently dated eruption in Antarctica was a VEI-4 in the Hudson mountains. That was 2000 years ago.

            • Problem is that dating and research is still a bit… scarce (putting it mildly). On the other hand, I would not like to be the one climbing them carrying equipment.

            • Overall, I think an increase in activity will happen in Antarctica if the ice melts. In Iceland, there is some remnants of larger glaciers at higher elevations, but there is not a huge amount of ice left to melt, at least not enough to produce similar eruptions to the last ice age.

            • Or the fact that there is nothing left to date in the first place. There needs to be organic material for radiocarbon dating, like wood or plants. Does that grow in Antarctica? No. But there is barely any research. That is where the GVP comes in handy.

          • {snicker} “Smurf”

            That is a term that has achieved a definition separate from when the word was first coined. It’s a verb and a noun.

            To smurf, is to adopt a false identity to sway opinion in a discussion forum. Similar to “sock puppet”, but a sock puppet is the alternate log in done by someone with an opinion in order to support their own position.

        • As far as i recall from geology classes far too long ago, (and it was a long time ago and my memory is not great). Australia formed from west to east, some of the oldest rocks in the world can be found on the western side of Australia. The east coast was definately influced by subduction somehwere around the ordocivian onwards.

          In more recent times, perhaps as little as 20,000 years ago, a possible hot spot moved under neath victoria, North of and to the west of present day Melbourne, and is now somewhere of the coast, its relatively inactive, however there are large amounts of flood basalts on the western side of Melbourne extending into the country side, and the western plains is dotted with cinder cones. I think there might some older occurnaces/evidence of this hotspot further north into NSW around Dubbo

          • Hotspots that are overrun by cratons have a tendency to become silent. It is not that they become inactive, it is just that they can’t punch through the hard old thick gnarly rock of a craton.
            Just look at the worlds largest hotspot, the African Plume. All it can muster through the Tanzanian Craton is Ol’Donyo Lengai, the volcano with the worlds coolest lava (510C). Okay, I admit, a volcano that pretty much erupts CO2 in rock form makes me want to do a split and play lip banjo out of joy… 😉
            Point being, it takes a mighty torch to cut through a craton.

            • I wouldn’t necessarily call Ol’ Donyo entirely benign. That same area produced a few huge calderas from explosive eruptions, including the Ngorongoro crater, which is now one of Africa’s most famous wildlife preserves, and looks like a stunningly beautiful area. Not that Donyo will do that, but that area has more potential than I think it lets on.

            • One thing I’ve been curious about however – is that an actual hotspot below the Tanzanian craton, or is it a product of the rifting that’s trying to tear eastern Africa off the rest of the continent? I know that the rift traveled south, hit the craton, and split off towards the west (rift valley lakes), and slightly to the east (where current Kilamanjaro sits). Considering that Ol Donyo is directly south of the rift, wouldn’t it make more sense that the rifting created a crack in the craton, but couldn’t entirely split through it due to the strength of the craton?

              Also, how do you define rifts like the great rift valley in africa in terms of hotspot volcanism? It isn’t really a single “hotspot” in the same way the mid atlantic ridge isn’t a hotspot.

            • What was first the egg or the hen?

              In this case there is no real rift. Africa has been dragged over a plume/hotspot that is so large and powerfull that it behaves like no other plume on earth has done since The Deccan Traps, Siberian Traps and Alpha Ridge. This, is a continent buster that missed Pangea and got Africa as a consolation prize.
              Or in the immortal words of a certain BBC professor of geology, “A Wee Superplume”.

              It started it’s activity at the Afar Region, then torched a rift into existance as Africa moved up over it, picking up power as it went. Today it is so large and powerfull that it has left a bow-wake of magma after it, and it is so wide that the sides of it is still splitting loose the Tanzanian craton at the sides from the rest of Africa(accidentally creating the worlds largest known caldera Ngorongoro in the process).
              Only question is if is so powerful that it will finnish of the Tanzanian craton. It might actually do that. And that would be something spectacular. Ol’Donyo Lengai is just the start of that process, there will be more to come down the long years. And at the other end of the craton? Well, there you can most likely expect a LIP to pop up.

            • Cratons need a large plume to rip up. Look at the Colorado plateau. It wasn’t even scratched by the Basin and range extension. Weaker crust to the west of it was sundered and torn apart because of the hot mantle. It held up. In central Nevada, another episode of rifting would break the crust open.

              Think “Rio Grande Rift”

            • Ngorongoro is spectacular, but I’m pretty sure Toba, Yellowstone, and a few others are quite a bit larger. I Just saw the wikipedia article on it (which states it as the largest in the world) and that’s no doubt false. Just hop onto google earth and do the measurament if your’e curious.

            • Ngorongoro:
              350 square kilometres
              1 130 square kilometres
              ca 2200 square kilometres

              So, calderasize wise yes, it is not the largest. But, Ngorongoro did it in one blast, the original mountain was higher, and the crater is deeper. Both Yellowstone and Toba have done 3 blasts. And it state the largest single blast. So, I guess it is a question of favourite flavour. My opinion is, they are horking huge. 🙂

    • Of much greater interest is that we’ve had four quakes, albeit small, in the Dead Zone west of Vatnajökull. That is unusual.

      • How come this happens every time we talk about really large Icelandic eruptions?
        Seriously, I am soon gonna suspect that Irpsit is doing horrible things to Veidivötn every time he is hikeing 😉

        • Like planting remotely controlled IEDs in abandoned drill holes 5.4 km deep? He is indeed a man of unexpected resources! :mrgreen:

            • Its part of my evil plot to trigger an eruption for the first time ever, and it is going to be – yes you are right Carl – in Veidivotn.
              Hehehehe 🙂

              Now, those 3 quakes are probably only 1 or 2. The area is recently having more occasional quakes. Like Carl I have a guess that Veidivotn will have another eruption sometime this century. And it will be large of course.

              And now we seem to have evidence that at 5km depth, the crust there is not so plastic as thought. I remember geolurking work, where bedrock temperature over the entire dead zone should be quite high. Only when some strain is large things would actually snap and result in an earthquake. Like it happened now.

              by the way last time I was in Skrokalda I saw the SIL and the sign of “private road – not entering this road”. Obviously for the sake of geological respect, I respected the label and did not want to check the SIL. Although it was a rather easy thing to do. Just walk some 500 meters from the mainroad up the mountain. But I didn’t, and road now is mostly closed so any action you see is probably real one.

  12. Geographically speaking, I love the location of Shasta and Black Butte Volcanoes. Being the railroad buff that I am The Former Southern Pacific Shasta Subdivision runs right past both of them. Steam Locomotives replenished their tenders with water before heading North to Portland, Oregon or heading south towards Sacramento, California.

    Yes there does seem to be a bit of geothermal activity going on at Torfajokull as well as at Eyjafjallayokull after a very long quiet spell.

    • Uhoh…
      I just got psychic, I prophesize a long discussion on trains coming… 🙂
      (1, 2, 3… Mike Ross will now enter the Building)

      • Iceland only had two trains, neither was for passengers. Yepp. Waiting for one? No trains now in Iceland. It will not be for considerable time.
        Train named “Pioner” were used to haul rock from quarry uphill, to construction of Reykjavik Harbour two piers. They were steam powered, just like Geysir. Those survive, but few or any of the “cars”.

        • but few or any of the “cars”.

          They’ve propably been fitted with large block V-8s and beefed up suspension to be used in Icelandic off-road events…

          The fun way to collect tephra samples… picking it out of your hair.

          … I wonder how this looks on a SIL… It’s got to be similar to Gino and his Caterpillar.

          • dunno dude, big block or small block. Ein´t that much power in originals. One of them “pits” shown actually is only 2 km from a SIL, but it does not show on them days when there are competitions. Loaded eighteen-wheelers make more real tremour. These 4×4 are lightweight.
            Why “4 x 4” (three speeds forward, one backing – on all 4 wheels?)
            For me these are “Beefed-up All Drives” (BAD!)

            • 4 tires, 4 wheel drive.

              They use 4 x 2 for two wheel drive vehicles, but I would prefer “2 x 4”, that way you could be talking about a piece of lumber. I’ve seen dualies (4 tires on the rear axle) labeled as 4×4, but shouldn’t they really be 4×6?

              Side note. A friend that I used know had two brothers and all were avid hunters up on the Big Black river in Mississippi. His brothers would routinely get stuck with their 4x4s… he rarely got stuck. I think this is because in a 4×2, you are more picky about the path you take.

    • One of the steepest grades in the Continetal US too. I think Central Oregon and Pacific may still have trackage
      rights though there but haven’t kept up with them since I left Southern Oregon. I missed a chance at a cab ride with
      my old neighbor years ago, who was a retired SP engineer still working for CO&P at the time. He started as a
      Steam fireman and was one of the last Cab Forward guys on SP before the things were retired…
      What is a “cab forward/” well it was an answer to a vexing problem-that of travel through snow sheds and tunnels with
      little or no ventilation:

      Here there be Dragons…

      • One other thing the “Cab Ride” was in a EMD GP-38. If I had an offer of a ride in the cab of a big Steam Engine or
        a ride on a Space Shuttle I’d have to think about it…

  13. Today… I went to Destin. The hard way. Why? Because there is no easy way to Destin. At mile marker 31, I hopped off the interstate since there is a convenience store there that I frequent from time to time. I originally started frequenting it because when I was in the neighboring Shell station one time, I overheard the manager talking to a friend of his in a disparaging manner about the place next door. Dunno if he realizes that his acerbic demeanor cost him a customer or not. Personally, I don’t really give a shit one way or the other.

    Anyway, I went to the soda fountain to get a coke, and it was labeled as “out.” The clerk I usually see asked if he could help since I had turned to go get a bottled version of the same beverage. I mentioned the “out” sign. He and the other staff there traded a few comments back and forth about who had labeled it as such, and he went back and put in a new syrup case, bringing the machine back on line. As I filled my cup, it sputtered a bit and then frothed to the top as the CO2 came bubbling up. The clerk apologized for that and I noted “As long as it’s not encased in silica, we’re okay”

    Take a wild guess what was on my mind

    Anyway, this morning, as I was letting the rat dogs out to do their thing, I ran across a waveform.

    Here be “poppers”

    We’ve seen these before. Carl has from time to time noted that some quakes are “wet,” signifying a drawn out harmonic component to the shape of the quakes.

    A closer look at one of the “poppers” from above.

    There ya go. It has a drawn out envelope.

    Hint… this is not from a volcano. This is the waveform of me tapping an empty beer can with a stick. That harmonic component is the can resonating after getting tapped. Similar to this, as the pressure in a “chamber” cracks the walls, that excited the entire structure and causes it to “ring.”

    So, the next time you see a real waveform on a seismo that show “poppers,” you’ll have an idea of what is going on.


    NOTE: “Poppers” is not a geologic term. It’s just something that I came up with to describe the waveforms during Redoubts last festive event. Tornillos are similar, but they last much longer. Following the concept of a resonating chamber, flowing fluid/gas doing the same thing creates harmonic tremor.

    • Just brilliant! What would it look like if you:

      a) Struck a ½ full beer can?
      b) Shook a full but unopened beer can vigorously?
      c) Once the full can had quietened down but before the released gas had been re-adsorbed, you struck it?
      d) Opened the can without shaking or striking it immediately after the conclusion of experiment c?
      e) Repeated the full experiment with a large, plastic soda or coke bottle?

    • Hi Lurking

      quite cool.
      There is no P wave I think.
      did you try to fourier transform it to get the energy spectrum . ?
      There is also an harmonic component in the tail I think and the amplitude us going up a little in the end.

      • P wave may be close to the S wave as, I am guessing, whatever GeoLurking was using to detect the wave was close to the source. But could be wrong.

        • Can’t get much closer to the sound source…. the microphone was in the beer can, just inside the throat.

          Also, these were not ordinary beer cans. They are essentially the shape of a spun bottle and have a screw cap. This means that they are fully symmetrical.

          As for the waveforms, they were rendered using CoolEdit Pro. The spectral image is also from the program… I’m not sure of the transform that is uses, but it was set for Gaussian mode.

  14. On Topic (from the Wikipedia article)

    The summit was achieved (or nearly achieved) by John Muir, Josiah Whitney, Clarence King, and John Wesley Powell. In 1877, Muir wrote a dramatic popular article about an experience in which he survived an overnight blizzard on Mount Shasta by lying in the hot sulfur springs found near the summit.


    • This begs the question “How acidic is that sulphuric spring and could anyone really spend a night in one without any ill effects”? I read that too as I was gathering material for the article, but to me it seemed a fanciful embellishment, a sort of “The Adventures of Captain Kettle” story. I’m not saying it can’t be true, just that it seems too good to be true.

      • That depends a heck of a lot. I have been in sulphuric hot springs, one time in Tunisia I spent hours floating in one as I consumed cold beers. I guess it depends a lot, from almost instantly starting to melt to getting a Spa quality soft skin peel that would cure almost any skin condition the party might have suffered from, including lice and scurvy.

  15. Off Topic.

    Schrödinger’s cat: a cat, a flask of poison, and a radioactive source are placed in a sealed box. If an internal monitor detects radioactivity (i.e. a single atom decaying), the flask is shattered, releasing the poison that kills the cat. The Copenhagen interpretation of quantum mechanics implies that after a while, the cat is simultaneously alive and dead. Yet, when one looks in the box, one sees the cat either alive or dead, not both alive and dead. This poses the question of when exactly quantum superposition ends and reality collapses into one possibility or the other.

    Something that Schrödinger failed to take into account was Murphy’s Law. Under Murphy’s law, the most troublesome result is what you will get when you look into the box.

    If the cat has a propensity to claw the face of the first person that it sees when it has been trapped in a box… that that is when you will get (a live and very pissed off cat). On the other hand, if Schrödinger would have to deal with a distraught wailing little girl who discovers her pet cat is dead, that is what he will get.

    Younger kids don’t take the death of a pet very well. One evening some of my fellow gamers met up on TeamSpeak to go out and conqueror the game universe and we were met with one of our party who had to keep checking the grill. Curious, we inquired what he was cooking. It turned out that the was not cooking at all. He was trying to cremate a hamster. It was his little girls pet. His wife had found it dead, and had called him while at work. She was worried that the girls would get home from school before he got off of work. He told her not to throw it away, since she might look in the trash bin while using it later. He also told her not to blurry it, since the dog and/or cat may dig it up. For the time being, he told her to wrap a piece of foil around it and put it into the freezer until he got home. So, she did. The plan was for the hamster to have “gotten away” to parts unknown.

    So.. here we are at 8 pm with him getting up to check the grill to see how far along the cremation had gotten along. Laughing hysterically… I had to explain to him that the grill was not going to get hot enough to turn the bones into ash. He let the process go along until the hamster was quite done… nothing more than a crispy morsel of ex hamster. I think that we advised him to pulverize it with a hammer if he wanted to reduce the size any further. But the final solution was to bin the hamster remains somewhere near work.

  16. Important notice:

    The eagle-eyed may have noticed that the Wiki article on Mount Shasta says that the Misery Hill cone formed as recently as 15,000 to 20,000 years ago. Please note that there is no citation in the Wiki article. Furthermore, the CVO states that Misery Hill cone formed “less than 130,000 years ago”. In this article, I have accepted the California Volcano Observatory figure as the correct one.

  17. @grumpybear

    Regarding Aussie volcanism, have you read Intraplate Volcanism in Eastern Australia and New Zealand? If you haven’t I recommend that you do, its an amazing compilation.

      • Hi Schteve, yes it its 🙂

        Actually, I have had a little chat with Wally Johnson via e-mail, real top guy, sent me through some things in the post 🙂

    • Yup! But the real show is going on on the SW flank. Check out the Bezymianni webcams.
      From all the illuminated steam I would say the lava flow has readily exceeded the flank. Look at all the steam piled up on Kamen´s flank!
      Image and video hosting by TinyPic
      Kvert: “Strong explosion occurred at the pass between Klyuchevskoy volcano and Kamen volcano at 08:20-08:30 UTC on October 11, 2013. Ash plume rose up to 6-7 km a.s.l. end extended to the east of the volcano. Probably a new flank eruption began at the pass between these volcanoes.”

      GVP on Kamen: “The steep-sided Kamen stratovolcano lies at the center of a N-S-trending chain of volcanoes, flanked by Bezymianny and Kliuchevskoi. The sharp-peaked, 4585-m-high Kamen is Kamchatka’s second highest volcano, topped only by its neighbor Kliuchevskoi. Kamen formed during the late Pleistocene, but activity continued into the Holocene (Melekestsev et al., 1990). A major slope failure about 1200-1300 years ago removed much of the eastern side of the volcano, producing a massive 4-6 cu km debris avalanche that traveled more than 30 km to the SE.”

      • wow, this is ramping up. Interesting how the new vent (if one has formed) hasn’t reduced pressure feeding the top vent as there is still pretty high fountaining going on there.

Leave a Reply

Please log in using one of these methods to post your comment: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s