3 ms·

Where are you getting the 2.5m figure from? The article you linked doesn't give a figure as far as I can see, but it says sediments have been found 4m above _c

by Merad 4y ago

Where are you getting the 2.5m figure from? The article you linked doesn't give a figure as far as I can see, but it says sediments have been found 4m above _current_ tide levels and that water went 29km inland in Scotland. Both of those figures seem to be at odds with a relatively small 2.5m tsunami (for comparison, the Fukashima earthquake produced a 15m tsunami).

eesmith 4y ago
https://www.sciencedirect.com/science/article/pii/S1463500314001164?via%3Dihub https://www.sciencedirect.com/science/article/pii/S146350031... (reference [13] from Wikipedia) comments: > The north-eastern coast of the UK experienced waves between 3–6 m, much like the eastern coast of Scotland ... Wave heights are predicted to be around 1 m on the UK coast and up to 5 m on the northern coast of Doggerland. The maximum elevation of Doggerland here is less than 10 m, with large areas of less than 5 m. It is therefore possible that much of Doggerland would have been flooded by such a wave. In reading now about the factors involved in this work, one issue is the amount of post-glacial rebound. While I've found that Scotland has rebounded a lot, I can't figure out how much that has been since 8,000 years ago. If I read figure 1 of http://people.rses.anu.edu.au/lambeck_k/pdf/152.pdf http://people.rses.anu.edu.au/lambeck_k/pdf/152.pdf correctly, the Bridge of Earn, Firth of Fourth was 4 meters lower, relative to sea level rise back then. I also know that geography can cause tsunamis to have local effects which are much stronger than average, as when a narrowing bay channels the wave upward. But I have no clue how that relates to the deposits seen in Scotland. Edit: and figure 3 seems to say Dogger Bank was 6 meters higher (relative to sea level) than now, again, due to post-glacial rebound effects.
bandibus 4y ago
I got the 25 metre figure from a paper on the Storegga collapse - and I'll return and cite this when I'm back at where my notes are. It's the upper limit of the cited proposed model of what happened. It looks like Britannica is referencing the same model here (although I'm not claiming Britannica is a rock-solid source for the facts): "Some models of the Storegga slides estimate that tsunami waves exceeded 20–25 metres (65–80 feet) in height along the coast of the Shetland Islands, 10–12 metres (33–39 feet) along the Norwegian coast, and 5 metres (16 feet) along the coast of eastern Scotland." https://www.britannica.com/topic/Storegga-slides https://www.britannica.com/topic/Storegga-slides
- eesmith 4y ago
  https://www.sciencedirect.com/science/article/pii/S1463500314001164?via%3Dihub https://www.sciencedirect.com/science/article/pii/S146350031... comments > The resulting tsunami had run-up heights of around 10–20 m on the Norwegian coast, over 12 m in Shetland, 3–6 m on the Scottish mainland coast. ... > We compare results from our multiscale model to previous results using constant-resolution models and show that accounting for changes in bathymetry since 8.15 ka, neglected in previous numerical studies of the Storegga slide-tsunami, improves the agreement between the model and inferred run-up heights in specific locations, especially in the Shetlands, where maximum run-up height increased from 8 m (modern bathymetry) to 13 m (palaeobathymetry). The Time Team episode (mentioned elsewhere here) says the wave at Doggerland was up to 10 meters. https://youtu.be/XTvOcm5dgDI?t=1835 https://youtu.be/XTvOcm5dgDI?t=1835 . The most recent publication I found on the topic is https://www.frontiersin.org/articles/10.3389/feart.2021.767460/full https://www.frontiersin.org/articles/10.3389/feart.2021.7674... : > The Storegga tsunami has previously been theorized as having brought about a swift and catastrophic end to Doggerland, the submerged palaeolandscape of the southern North Sea (Weninger et al., 2008). However, a more nuanced understanding is beginning to emerge in the wake of numerical modelling of the wave’s dispersal (Hill et al., 2014; Hill et al., 2017), and the discovery of the first confirmed evidence of the tsunami from a submarine context, “core ELF001A” from the “Southern River” submerged river valley, recovered by the Europe’s Lost Frontiers team (Gaffney et al., 2020). Clearly the Storegga tsunami hit some of the coastlines of the southern North Sea with considerable force, but the severity of this impact was probably variable (Walker et al., 2020). It cites "run-up heights in excess of 25 m recorded in parts of Scotland and Norway".
  - bandibus 4y ago
    Thanks for that. Yep - I think the widely (wildly) varying numbers are due to there being various models currently being explored. The paper I referred to was recent but not "2020" recent. I'd also trust Gaffney's team's findings as the Lost Frontiers team are at the cutting edge of all this.

by Merad 4y ago

eesmith 4y ago

https://www.sciencedirect.com/science/article/pii/S1463500314001164?via%3Dihub https://www.sciencedirect.com/science/article/pii/S146350031... (reference [13] from Wikipedia) comments: > The north-eastern coast of the UK experienced waves between 3–6 m, much like the eastern coast of Scotland ... Wave heights are predicted to be around 1 m on the UK coast and up to 5 m on the northern coast of Doggerland. The maximum elevation of Doggerland here is less than 10 m, with large areas of less than 5 m. It is therefore possible that much of Doggerland would have been flooded by such a wave. In reading now about the factors involved in this work, one issue is the amount of post-glacial rebound. While I've found that Scotland has rebounded a lot, I can't figure out how much that has been since 8,000 years ago. If I read figure 1 of http://people.rses.anu.edu.au/lambeck_k/pdf/152.pdf http://people.rses.anu.edu.au/lambeck_k/pdf/152.pdf correctly, the Bridge of Earn, Firth of Fourth was 4 meters lower, relative to sea level rise back then. I also know that geography can cause tsunamis to have local effects which are much stronger than average, as when a narrowing bay channels the wave upward. But I have no clue how that relates to the deposits seen in Scotland. Edit: and figure 3 seems to say Dogger Bank was 6 meters higher (relative to sea level) than now, again, due to post-glacial rebound effects.

bandibus 4y ago

I got the 25 metre figure from a paper on the Storegga collapse - and I'll return and cite this when I'm back at where my notes are. It's the upper limit of the cited proposed model of what happened. It looks like Britannica is referencing the same model here (although I'm not claiming Britannica is a rock-solid source for the facts): "Some models of the Storegga slides estimate that tsunami waves exceeded 20–25 metres (65–80 feet) in height along the coast of the Shetland Islands, 10–12 metres (33–39 feet) along the Norwegian coast, and 5 metres (16 feet) along the coast of eastern Scotland." https://www.britannica.com/topic/Storegga-slides https://www.britannica.com/topic/Storegga-slides

eesmith 4y ago
https://www.sciencedirect.com/science/article/pii/S1463500314001164?via%3Dihub https://www.sciencedirect.com/science/article/pii/S146350031... comments > The resulting tsunami had run-up heights of around 10–20 m on the Norwegian coast, over 12 m in Shetland, 3–6 m on the Scottish mainland coast. ... > We compare results from our multiscale model to previous results using constant-resolution models and show that accounting for changes in bathymetry since 8.15 ka, neglected in previous numerical studies of the Storegga slide-tsunami, improves the agreement between the model and inferred run-up heights in specific locations, especially in the Shetlands, where maximum run-up height increased from 8 m (modern bathymetry) to 13 m (palaeobathymetry). The Time Team episode (mentioned elsewhere here) says the wave at Doggerland was up to 10 meters. https://youtu.be/XTvOcm5dgDI?t=1835 https://youtu.be/XTvOcm5dgDI?t=1835 . The most recent publication I found on the topic is https://www.frontiersin.org/articles/10.3389/feart.2021.767460/full https://www.frontiersin.org/articles/10.3389/feart.2021.7674... : > The Storegga tsunami has previously been theorized as having brought about a swift and catastrophic end to Doggerland, the submerged palaeolandscape of the southern North Sea (Weninger et al., 2008). However, a more nuanced understanding is beginning to emerge in the wake of numerical modelling of the wave’s dispersal (Hill et al., 2014; Hill et al., 2017), and the discovery of the first confirmed evidence of the tsunami from a submarine context, “core ELF001A” from the “Southern River” submerged river valley, recovered by the Europe’s Lost Frontiers team (Gaffney et al., 2020). Clearly the Storegga tsunami hit some of the coastlines of the southern North Sea with considerable force, but the severity of this impact was probably variable (Walker et al., 2020). It cites "run-up heights in excess of 25 m recorded in parts of Scotland and Norway".
- bandibus 4y ago
  Thanks for that. Yep - I think the widely (wildly) varying numbers are due to there being various models currently being explored. The paper I referred to was recent but not "2020" recent. I'd also trust Gaffney's team's findings as the Lost Frontiers team are at the cutting edge of all this.