A Little Ash Never Killed Nobody

Warning signs: we see them every day, from hazard signs on the roads, to symptoms in sickness. Some warning signs are only found in certain areas, for example mass wasting signs are usually only next to steep slopes. When getting sick, most people will experience symptoms before a full blown fever. It just so happened that the day we learned about warning signs, I was beginning to have warning signs of a cold myself (talk about one with the classroom). The warning sign that caught my eye though, was a thin layer of ash in between non-Minoan ash and Minoan pumice when our class visited Caldera Beach.

Known as Phase 0, Santorini had a small (less than one km high) sub-plinian eruption consisting of ash before the main eruption of the volcanic vent. Phase 0 was produced by a subaerial, phreatomagmatic explosion. For any  non-geologist, a phreatomagmatic explosion is an explosion produced by steam. This steam is formed when water is flash heated by magma, lava or hot rocks. Even though the explosion was subaerial, there is evidence the eruption was wet due to the low percentage of vesicles, along with the presence of angular clasts and smaller ash pieces (Friedrich). This thin layer of ash can only be seen on certain sections of the island because of the prevailing wind moving south during the beginning of the eruption (Fig. 1). Phase 0, therefore, encompasses sites such as Akroteri, Caldera Beach, and Vlychada Beach. The thickness of the ash also varies depending on location; The ruins of Akroteri held roughly eight cm of brown ash in its walls (Fig. 2).  Caldera Beach had a thin, less than five cm layer in between non-Minoan ash and phase one pumice fall. Lastly, on the far southeast boundary of Phase 0, we saw Vlychada with only three cm of ash. As we saw in the field, Phase 0 thins around the edges of the deposit as well as farther away from the erupting vent.

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Fig.1 Note the large yellow circle, this is a rough outline of where the vent from the Minoan Caldera was located. The red triangle symbolizes Phase 0 ash fall. The purple pin indicates Akroteri, the blue pin illustrates Caldera Beach and the green pin represents Vlychada. Note the distance from the vent to Akroteri is roughly 6 km.
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Fig. 2 Note the orange, elongated oval in between Phase 1 and Akroteri, this is Phase 0. Also note Phase 0 is barely visible to the common eye.

Though each volcano is unique in their own way, many volcanoes that produce plinian eruptions will have a throat clearing period or a Phase 0. Mt. Vesuvius in Italy, known for the destruction of Pompeii, erupted a thin layer of ash, roughly seven hours before the main eruption in 79AD (Cioni et al 2000). A more recent example includes Mt. Pinutubo of the Philippines which erupted in 1991. Along with many other precursors, there was a small, ash filled steam eruption before the main eruption (Pappas). Though every volcano is unique, both eruptions demonstrate that precursors are common for volcanoes (For more on warning signs of eruptions, see Defcon 0 by Katie  Crowley).

Now, you may be asking at this point, why was Phase 0 special if other volcanoes can also produce phreatomagmatic explosions? Well, Phase 0, along with a few other warning signs, pushed the Minoan people to leave Akroteri. It warned them to pack up their belongings and rid themselves of the dangers on the island (pretty amazing right?). Evidence of their departure included: bed frames being stacked and pushed against walls, pots being placed all in one room and lack of footprints in the ruins of Akroteri (Fig.3). It wasn’t Phase 0 that was unique, it was how the people of Akroteri interpreted the ash fall and saved themselves that made phase 0 special.

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Fig. 3 Note the broken pots stored to the side in the room.

At this point you’re probably thinking, what do warning signs have to do with us, why is it important to the modern generation? I was born and raised in the Pacific Northwest of the United States. Many people, including Oregonians, are unaware of th massive earthquake and tsunami that will soon hit our shores. Off the coast of Oregon is a subduction zone where the Juan de Fuca plate is merging under the North American plate (Fig. 4). Eventually, the two plates will snap back within the next 50 years, producing a potential 8.0 and above magnitude earthquake (Goldfinger). Not only could this earthquake create a 40 foot high tsunami, destroying the coastline I grew up around , but it could result in volcanic activity along the Cascades. These three aspects combined could cause millions of thousands of dollars in damage in the Portland City area and along the coast. If that’s not scary, I don’t know what is. Therefore, I look for warning signs everyday so that when the earthquake does occur, I am prepared (hopefully I’ll be in a park and not at the beach). My livelihood, among with many others, is threatened by the well overdue earthquake and tsunami haunting the Pacific Northwest.

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Fig. 4 Above illustartes the Juan de Fuca Plate subducting under the North American Plate on the Cascadia Subduction Zone near Oregon and Washinton.

For me, when I learned about Phase 0, I was in utter shock. Not only at the fact that the Minoan people had vanished but at the fact that today, volcanologists use highly technical equipment to determine when a volcano will erupt whereas the people of Akroteri based their decision on the thin, barely visible, layer of ash. Phase 0 was not only important for the survival of the Minoans but it is also essential to archeologist who study the lifestyle of the Minoans. The thin layer of ash, that most tourists overlook, demonstrates the advance and intelligent culture of the Minoans. Understanding the geological aspect of where you live is extremely important. Even if you don’t live next to a plate boundary or volcanoes, warning signs in geology are vital to survival, the people of Akroteri knew that, do you?

Sources:

Cioni, R., L Gurioli, A Sbrana, and G Vougioukalakis . “Precursors to the Plinian Eruptions of Thera (Late Bronze Age) and Vesuvius (AD 79): Date from Archaeological Areas .” (2000): 722. Print.

Friedrich, Walter L. Santorini . Denmark : Aarhus University Press, 2009. Print.[2]

Goldfinger, Chris . “Odds are 1-in-3 that a huge quake will hit Northwest in next 50 years.” Oregon State University , 24 June 2010. Web. 12 June 2015. <http://oregonstate.edu/ua/ ncs/archives/2010/may/odds-huge-quake-Northwest-next-50-years>.

Pappas , Stephanie. “Pinatubo: Why the Biggest Volcanic Eruption Wasn’t the Deadliest.” LiveScience. 15 June 2011. Web. 12 June 2015. <http://www.livescience.com/14603- pinatubo-eruption-20-anniversary.html>

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8 thoughts on “A Little Ash Never Killed Nobody”

  1. Rachel,

    At the beginning of this post when you are talking about warning signs of a volcano is like the signs of a cold/sickness, I started laughing because everyone here is sick, and they didn’t use the ‘warning signs’ like the Minoans did. You were saying that the warning phase was common in other volcanoes like Pinutubo and Vesuvias. It made me curious of what the common deposit cycle is for most volcanoes… Like is there always pumice before pic flows? Or is it only situational… Anyways good publish

    1. Hi Rachel,

      I’m planning a trip to the Northwest in the next couple of weeks, and now I’ll keep vigilant for any signs along the coast. Actually, did you happen to read about that family who was vacationing in Thailand in 2013? The family was on the beach when they saw the water retreating and the fish flopping on the sand. It was their youngest daughter who said “Let’s get out of here and move to higher land. I saw this on NOVA…” so they did, and they lived. Goodness. Your connection with Santorini and your home-region of the Northwest shows that you are making connections beyond your homework. Very interesting.

      Your post kept me wondering what do you think encouraged the population to move, quickly. Clearly the decision was a community decision and it seemed it was highly organized according to Katie’s and your post. Do you think that like you, maybe they knew a bit about their environment and what may happen? Maybe they had geologists, pre-professor Skinner’s who knew what the signs would lead to? Maybe there was a 5th caldera no longer visible for us to see? Maybe… I always learn from first-hand speculators. Your speculations are encouraged and with your professor, text, and classmates near by, I’m sure that you will provide an insight that the rest cannot possibly imagine.

      I’m glad that you collaborated with Katie. Together you provide a bit to think about…

      1. The people at Akroteri were a highly advance civilization which can be seen from the archeological artifacts found in the ruins. Many anthropologist believe the people of Akroteri understood their environment because they lived there for so long. It is also interrupted that they had seen Smaller eruptions before the major one that warned them there was going to be some damage done to the island. The entire city is not fully excavated yet which means there is a chance the people could have possibly been in a room that is still not excavated. But, there is evidence of items being packed away as if the people were leaving the island. One thing you have to remember though is that everything is still up for interpretation. Many archeologist believe they were smart enough though to leave the island before the volcano had fully erupted from other evidence of departure.
        For your trip, if you’re visit Oregon be sure to check out Portland, it is probably one of my favorite cities in the U.S. and I have been to over half the major cities in the U.S. (my dad loves road trips). Some places that are cool to visit include: Voodoo donuts and Salt & Straw of Portland as well as Pikes Place and the Gum Wall of Seattle! Definitely worth the visit, you meet some of the weirdest people. Thank you for you comments and I hope you have a great time on your travels. Cheers!

  2. Hi Rachel,
    You chose a great title for your second blog. It provides a nice entry-way into exploring Phase 0. I am wondering how your introductory comment can lead to Phase 0 more clearly for your readers who are not members of the group in Santorini. It would help if you described the warning signs on getting sick, explaining it in a similar way to how you would explain Phase 0. What is the ash part when you have warning signs for getting sick? Does everybody have it (Ray said no)? Does every volcanic eruption have a phase 0?

    I would also be interested in knowing what the destruction of Vesuvius and Pompeii was? Did the people not make it out? Were the bodies found? That would then show that the Minoan people were different since there were no bodies found and there were clear signs that they knew the eruption was coming. What made them different? Did they learn from other eruptions? Or was the eruption different?

    It was great to see you make connections to the Northwest of the U.S. It’s one of your strongest paragraphs and give me much to think about.

    Good luck with your final blog entry. It’ll be great to see where you are taking us with it.

    1. I would say ash, in comparison to a cold, is like a tickle in the throat or a stuffy nose. It is the sign you get right before heavy coughing and a fever. More than half the group ended up getting sick a couple days after were learned about warning signs which is why I mention it because I found it quiet funny.
      I mention in the third paragraph that not all volcanoes get a phase 0 but many volcanoes do have warning signs which can include but are not limited to: earthquakes, changes in gases and deformation which will all be discussed in this weeks blogposts (all the more the reason to continuing reading the blog). Pompeii is a little different compared to Santorini because they are two different types of volcanoes. Pompeii is a composite cone compared to Santorini which is a caldera and calderas have the strongest explosions (think of Yellowstone erupting compared to the eruption of Mt. St. Helens, Yellowstone being Santorini). This doesn’t mean though there was no warning signs at Pompeii. It is interpreted that the people of Pompeii left the area after a heavy layer of ash fell on the city but then returned later that day to collect personal items. They just happened to be in the wrong place at the wrong time though because when they returned the big explosion occurred. There were no actual bodies found at Pompeii because they decomposed but through mold casting, they were able to salvage where the bodies would have been. Both civilizations understood their landscape, the people of Akroteri though we’re just a little bit more lucky when it came to timing though! Thank you for your comments and be sure to read next week to learn more about warning signs of volcanoes!

  3. Rachel – This post would benefit from organizing it into smaller paragraphs. When writing for the web, remember to organize your thoughts into short paragraphs (3-4 sentences). Also, when you talk about phase 0 being a warning, it is important to remind the reader that it is ‘interpreted’ as a warning based on many different lines of evidence (which you state). I too am glad to see how you wove in your own fears about the Pacific Northwest. Its something I hear you talk a lot about, and knowledge I think is important for everyone to know.

    At the end, please list your references on separate lines so they are not all jumbled.

    So what is up next?

    1. Yes, sorry when I tried to page break my sources it wouldn’t let me which is why it got are jumbled up at the bottom. Also I was unsure how to separate the paragraphs because I felt as though all the information needed to be together in a single paragraph or else the flow would not work. For the next post though I will work on making smaller paragraphs easier for the readers because I know some readers do get bored with longer paragraphs. I was happy I was able to write about the Pacific Northwest because I feel as though a lot of people do not understand the dynamics going on there and it would be a major disaster if it did happen. I also think if people really wanted a disaster movie they should stop exaggerating the San Andres Fault and make a movie that is actually realistic about the Oregon coast. Anyway, thank you for the feed back and I have an idea about my next post which I think would be beneficial to the readers.

    2. Okay I went back through again and realized some of the paragraphs did not split where they were suppose to and I fixed the sources so now the paragraphs are smaller and what they were suppose to be when I originally typed it out. They are still long but they are better than before.

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