A Storm’s a Brewin’

It’s Monday, November 30th, 2015, 11:30 am. Today is the day I will be learning about a topic I have anticipated since the beginning of Geologic Disasters. I will be learning all about rivers and flooding! Sitting in class I hear moans and groans about this. A lesson that seems so tedious and dull to my classmates was actually fascinating and thrilling to myself. I was finally going to learn about a topic I could personally connect with.

Rivers and floods are nothing new to me. Northern Arizona is filled with hidden dry washes that wind all throughout the towering Ponderosa forest. Every summer where I grew up, I experience flash floods, now I have learned that floods occurred during the Santorini cataclysmic eruption!

In the middle of a chaotic volcanic eruption, not only was there falling ash and pumice, but there was also heavy amounts of rain pouring down in, resulting in flash floods. The flash floods occurred due to volcanic weather. Volcanic weather is the result of rising hot ash drawing in heat and then lifts surrounding air. The air expands, cools, then causes water to condense and fall down as rain! (Figure 1) Interestingly, volcanic eruptions can create their own weather system! In the midst of an eruption, lightening, rain, and flooding occurs because of volcanic weather.

(Figure 1) More detailed description of volcanic weather that outlines the process

Evidence of volcanic weather must be found in order to assume that flooding occurred. A remote beach located on the northern tip of Santorini called Cape Mavropetra provided the necessary details needed to make the assumption that volcanic weathering did occur during the eruption. This evidence is a phenomenon called scour channels! Scour channels are a stream erosional feature (Figure 2). It proves that there had to be large amounts of flooding at the same time as the eruption. It took me quite a while to soak in this feature, an erosional feature that was nothing but foreign to me.

(Figure 2) Evidence of volcanic weather at Cape Mavropetra called scour channel


Scour channels also provide more evidence of volcanic weathering. It is clearly evident that there is a dipping motion occurring in the rock. There is well preservation of the cut bank and point bar in the scour channel (Figure 3). The cut bank is the outside of the river, it is also where erosion occurs. As opposed to the cut bank, the point bar is the inside of river. The inside of the point bar is where deposition occurs, such as sand and sediment (Figure 4).

(Figure 3) More detailed description of volcanic weather that outlines the process


(Figure 4) Outline of a point bar and cut bank in a stream

Volcanic weather is like nothing I have ever heard of. It can have a very short duration of a few hours or a large duration of up to a week. The duration of volcanic weather during the cataclysmic eruption of Santorini is estimated to have lasted from a few hours to a day! Just within a day, volcanic weather created a large flood and channel, approximately 15 meters in width!

Today, it’s Sunday, June 12th, 5:50 pm. The presence of a scour channel at cape Mavropetra provided two pieces of evidence that volcanic weather did occur. The scour channel first identifies a clear outline of a river, it also contains remarkable preservation of the cut bank and point bar. It was very hard for me to accept that volcanic weather created floods while a colossal eruption was occurring at the same time! I knew that the eruption created layers and layers of pumice and ash; however, I never gave much thought to think of the possibility of flooding.

8 thoughts on “A Storm’s a Brewin’

  1. Hi Sadie – Volcanic weather is a fascinating process. Most people aren’t aware that large Plinian eruptions can create their own weather systems. Importantly, also, the interaction of seawater at the vent would have been releasing enormous amounts of steam into the atmosphere, which then would condense on the ash and rain down onto the landscape. Often cataclysmic eruptions cause not only flash flooding near the eruption, but within the region as well.

    Just recently in Indonesia (2014), tornadoes were filmed in front of and behind pyroclastic flows rushing down the sides of Mt. Sinabung.

    I know that you were excited to write about streams and flooding for this blog post. I do feel like the middle and end of the blog loses your voice and experience. I would moderate your use of exclamation points. As a reader (trying to be a non-geologist) I don’t really get why a 15 m wide scour channel is exciting. Rather, writing about why this channel is important evidence for flash flooding during the eruption (not necessarily its width, etc.). For your next post, focus on using the facts you learn to support your story (explaining why they are important in the context of a more vivid narrative).

  2. Hi Sadie,

    It’s exciting for me as a reader to see how passionate you are about this subject. At first I was curious about how this flooding process related to Santorini, and as I kept reading I started understanding why this is such an interesting topic. I really started to understand the significance of flooding in relation to Santorini in your conclusion (second to last paragraph). I learned that in a short amount of time, a large part of the island was affected. As an outside reader, I was able to learn about this process, and how it is directly significant for Santorini. Your images of the actual rock formations made this connection even stronger, and it was insightful for me to visualize this concept as I read and learned along with your post.

    For the most part, I think you effectively explained geological concepts to an outside audience. Processing information did become a bit more difficult towards the middle of your post. I agree with Dr. Skinner that your narrative dips a bit in the middle of the post and I think this may contribute to my difficulty since the discussion was solely about geology without a personal interjection. I specifically got a bit confused when reading about scour channels (5th paragraph) because the information came rapidly. It was when I saw your drawing (Figure 4) that I was able to connect the dots and visualize what your were discussing. This is an effective use of an image.

    For your last post, try keeping your narrative a bit more consistent. You can do this even by walking your audience through your research process of this topic. What were your initial thoughts about the topic? What surprised you the most while doing your research? Inserting your own journey (even about research) can be fun for your audience who is learning this information right along with your post!

    Overall, this is a strong post. Your use of images supports readers as they learn about flooding, and your passion about the topic inspires readers to also be excited while reading. For your last post, make sure to strengthen your narrative throughout, and explain early on in your posts how your research topic specifically relates to Santorini.

    Great work!


    1. Marisa,

      Thank you for taking the time to read my post! I do agree with both you and Dr. Skinner. I did lost my voice through out the post. I will try to incorporate more of my experiences in my next post as well as your other comments.

      Thank you,
      Sadie Segovia

  3. Hi Sadie,

    Your enthusiasm for this natural phenomenon is refreshing! The post was interesting and informative while also carrying through your sense of excitement for what you were studying. I think you did well in keeping your personal experiences in the beginning and then continuing to explain the more scientific side of flooding in the rest of the post.

    I would like to point out the repetition in the third paragraph. While repetition does serve to make sure your reader gets the important points, if over used it can sound like filler. Luckily, you used just the right amount to ensure your readers understand volcanic weathering, which is a term used throughout the post.

    By adding definitions of terms and also providing diagrams, you made terms like “point bar” and “cut bank” very clear. Talking about the diagrams, it was also a good call adding pictures of the real life feature. It helps your reader envision what you’re talking about. It’s also a neat feature in blogs that’s not found in most research papers, so good job utilizing it!

    1. Nicole,

      Thank you for pointing out the repetition in the 3rd paragraph. I didn’t notice it until you brought it to my attention. I greatly appreciate you doing so! Thank you for your feedback!

      Sadie Segovia

  4. Sadie,

    I loved how you tied in what we learned on Santorini with what we learned in class which seemed like forever and a half ago! It’s so exciting to be able to apply knowledge like that.

    I enjoyed reading your blog post. The figures you decided to use were really helpful for me in refreshing my memory of point bars and cut banks.

    I’m glad you talked about volcanic weather because I agree with Lisa, it’s a very fascinating phenomenon that this earth of ours is capable of!


  5. One additional comment – volcanic weathering is not a process. Volcanic weather systems are produced when hot ash rises into the atmosphere. Then those storms produce flash flooding, thunder, lightening, acidic rain and in some cases tornadoes. Flash flooding them produces the scour channel.

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