Highstorm thought

[strmblsd he/him]

Ok so should because of how a highstorm is cause massive waves at a coast? Such massive winds and stuff should cause tsunami size waves if I am correct.

I wanna hear other thoughts on this too because I am probably wrong but it makes sense that there would be tsunami size waves at a coast right?

[Treamayne]

2 hours ago, strmblsd said:

Ok so should because of how a highstorm is cause massive waves at a coast? Such massive winds and stuff should cause tsunami size waves if I am correct.

I wanna hear other thoughts on this too because I am probably wrong but it makes sense that there would be tsunami size waves at a coast right?

Not really (depending on your "definition" of Tsunami). Tsunami are normally caused by oceanic earthquakes or ocean-bottom volcanic eruption. When I was in Okinawa (2001-2004) most Cat 4-5 Typhoons (Pacific Ocean hurricane) may cause 15ish ft swells (so the beaches used off-shore breakers to crash the swells before they could make landfall). However, most people who have not lived in a region prone to these environmental disasters tend to have the Hollywood idea of how a tsunami (50+ foot swells) looks; and that is not nearly as common as people think. Additionally, the water depth has a huge impact on storm swells. For example, a shallow bay cannot support a large storm swell, because wave height cannot be greater than average water depth (that's when waves "break" is when the trough hits the water depth, spilling the wave top over because it can no longer travel further at that height). That's why a Tsunami is more common in island nations (Hawaii, Japan) as the ocean depth tends to drop quickly, even close to shore. 

More info: Joint Typhoon Weather Center - Tsunami METOC FAQ Tsunami, Seichs, and Meteotsunami

That said, a true large Tsunami is horrifically devastating. We worked in the aftermath of the 2004 Tsunami (Indian Ocean) - and though US news covereage was eclipsed by Katrina, this was far worse (Satelite before and after example):

Spoiler

For days the military did nothing but fly in rations, dry ice, and medical supplies and fly out full of body bags (to prevent disease). 

Hope that helps.

Edited September 11, 2024 by Treamayne
SPAG

[+Lewis Nethur He/Him]

9 hours ago, strmblsd said:

Ok so should because of how a highstorm is cause massive waves at a coast? Such massive winds and stuff should cause tsunami size waves if I am correct.

I wanna hear other thoughts on this too because I am probably wrong but it makes sense that there would be tsunami size waves at a coast right?

No no, I believe you're basically on the right track on this point, only a little misguided. Highstorms are not really physically similar to any IRL Earth weather event is the crux of the problem. They travel insanely fast, blow absurdly hard, and always follow the same one directional path. If memory serves, the leading edge of the storms, the Stormwall, is described in-book as many hundreds of feet tall and almost supersonic. That's so ridiculously worse than a tsunami that it just strains credulity to compare the two phenomena, IE: a stormwall 1,000 miles inland from the coast over bare rock behaves so much more radically violent, extreme, fast, tall, deadly, and incomprehensibly vast than the absolute worst possible coastal tsunami event on Earth that, while they technically obey the same underlying physical principles, it almost seems like they legitimately do not and a lot lot lot of math and hand-waving had to go into their creation upfront to make them work at all. (Recall: Roshar is a completely artificial world architected by Adonalsium and 100% of the human population is comprised of refugees, immigrants, and their descendants who all settled their after Honor and Cultivation had already started playing with it without the other Shards)

[alder24]

12 hours ago, strmblsd said:

Ok so should because of how a highstorm is cause massive waves at a coast? Such massive winds and stuff should cause tsunami size waves if I am correct.

I wanna hear other thoughts on this too because I am probably wrong but it makes sense that there would be tsunami size waves at a coast right?

Maybe not a tsunami, but it should cause coastal flooding. Highstorms are a low pressure environment and they would raise the water level because of that. That water would then travel inland as far as it can. This is called a storm surge. Hurricane Katrina in 2005 produced a storm surge around 8.5 meters high, while the highest ever recorded was 13.4 meters created by cyclone Mahina in 1899.

Yes, it would be comparable to a tsunami at least by height and it would cause massive damage to low lying coastal settlements. However this is Roshar we're talking about, they battled storms for 7000 years, I'm sure they are well aware of this phenomena and build their cities higher to prevent flooding (for example this image of Kharbranth, which was once included in SoS -  just look how high the cliffs are and how tall are walls in the port).

 

2 hours ago, hwiles said:

If memory serves, the leading edge of the storms, the Stormwall, is described in-book as many hundreds of feet tall and almost supersonic.

Not supersonic. 370 mph or 600 km/h, which is half of the speed of sound. It's ridiculously fast. Twice as fast as the most severe storms on Earth. From Wikipedia:

Quote

The most intense storm in the Eastern Pacific Ocean by both sustained winds and central pressure was Hurricane Patricia. Its sustained winds of 345 km/h (215 mph) are also the highest on record globally.

 

[Quantus he/him]

28 minutes ago, alder24 said:

Maybe not a tsunami, but it should cause coastal flooding. Highstorms are a low pressure environment and they would raise the water level because of that. That water would then travel inland as far as it can. This is called a storm surge. Hurricane Katrina in 2005 produced a storm surge around 8.5 meters high, while the highest ever recorded was 13.4 meters created by cyclone Mahina in 1899.

Yes, it would be comparable to a tsunami at least by height and it would cause massive damage to low lying coastal settlements. However this is Roshar we're talking about, they battled storms for 7000 years, I'm sure they are well aware of this phenomena and build their cities higher to prevent flooding (for example this image of Kharbranth, which was once included in SoS -  just look how high the cliffs are and how tall are walls in the port).

 

Not supersonic. 370 mph or 600 km/h, which is half of the speed of sound. It's ridiculously fast. Twice as fast as the most severe storms on Earth. From Wikipedia:

 

I suspect crem buildup at the coasts would accumulate right at the tidal water marks and create natural berms against a lot of that storm surge (and settlements certainly could grow them intentionally).  A big part of what makes Hurricane Storm surge so damaging is that it comes rarely and unexpectedly, but a storm that comes every few days would be able to find a better balance with the coastal environment (with a little magic Crem help).  

To say nothing for the inexplicable fact that the coastal shape itself is maintained magically and against the normal natural pressures of wind and sea that would carve it harshly and in that single direction.  There's a bigger process standing in the way of major/sustained flooding, or anything that would actually change the shape of the coastline.   

[Duxredux he/him]

Oh cool, that course I took on natural disasters is relevant again.

Storm surge and how hurricanes operate are close to, but not exactly as people are describing them. First off, storm surge occurs specifically when a storm is transitioning from water to land, not the reverse. While moving across the water, the winds of the storm blow the water towards the land pushing it further inland until the storm itself arrives. Yes, the low pressure of the storm does create some lift in the water, but it is minor compared to the hours of wind pushing water towards landfall. It's this sustained pushing that relatively slowly forces water onto the coastline and is known as storm surge, and yes it will cause somewhat larger than normal waves, but not tsunamis. Hurricane storm surge is predictable - it happens pretty much every time, and depending on technology people will have days to prepare for the impact of the storm - they are extremely visible and seasonal.

In contrast, tsunamis are caused by sudden large scale displacement of water, such as an underwater earthquakes or volcanic eruptions as Treamayne stated, but also landslides. The jolt of displaced water travels extremely quickly laterally through the ocean and may be entirely unnoticed by ships as the water may only move vertically in deep water a few feet, but that displacement suddenly runs out of horizontal room when it hits coastlines and is translated to vertical water displacement - the tsunami wave. Tsunamis travel much, much faster than hurricanes, faster than Highstorms, and may require earthquake monitoring devices to detect. Response time is hours or minutes, depending on the location of the epicenter.

On Roshar, the principle of always build facing away from the Highstorm will still apply, but will largely extend to the coastline - which is pretty much a no brainer. Building a stormbreak along a beach would be super expensive and difficult to sufficiently stabilize. It's why many major Rosharan cities like Kharbranth or Thaylen City will preferentially build on the west coast. The Highstorm won't create a storm surge for western coasts, if anything it will create an abnormally low tide as winds push the water away from the shore. This is one of the reasons why the Everstorm made such a huge mess of Thaylen City - it was never designed to withstand the storm surge absent from the Highstorm and got pummeled more than inland cities that simply had buildings facing the wrong way. 

Edited September 11, 2024 by Duxredux