Tsunami-1

Johnny1A.2 · 06-18-2019, 10:07 PM

This time line superficially appears to have diverged from Homeline's path on July 19 1940. However, Homeline geologists argue that the actual divergence point would have to have been centuries earlier, with the effect becoming manifest on 19 July 1940. Either way...

1940 - Mauna Loa, the largest (in volume) volcano on the Big Island of Hawaii, began erupting in April, just as it did on Homeline. However, unlike Homeline (and our world), the dormant neighboring volcano, Mauna Kea, also began to display a certain amount of limited eruptive activity, in the form of cinder cone eruptions. The joint activity continued throughout April, May, and into June, and at this point Kilauea began to erupt as well. The cinder cone eruptions around the peak of Mauna Kea were not particularly problematic, but the lava effusions from Mauna Loa and Kilauea were another matter, becoming serious threats to life and property in some areas.

By this point, the Hawaii Territory was in a state of emergency and panic was beginning to set in in some quarters. Assistance was marshalled to help with locals and ships were prepared against the possibility of evacuations. War tensions, at least locally, receded somewhat in the face of the geological issues.

On 19 July 1940, however, events outran all preparations. Massive earthquakes originating under Mauna Kea appeared to trigger answering tremors under both Mauna Loa and Kilauea...and a large slab of the Big Island slid into the ocean.

The devastation in the Hawaiian Islands proper was near total. Immense tsunamis raced outward across the Pacific, bringing devastation to the western coastal regions of North and South America and throughout much of the eastern coasts of Asia. Australia was affected heavily, and much of the Dutch East Indies were devastated as well.

The world was stunned both by the unexpected geological calamity and by the devastation the immense waves generated. Among the effects were the near-total destruction of much of both Japan and America's Pacific naval power. The American Pacific Fleet had been advance-stationed at Pearl Harbor two months before the Event, and most of it was destroyed. Not that it would have made much difference had it remained in San Diego, because San Diego was also devastated. Along with the loss of ships, even more damaging in some ways was the loss of critical shore support facilities.

(Indeed, those ships out in the open sea were scarcely affected.)

The Pearl Harbor attack was wiped from history, and indeed the damage from the Event was sufficient that the Japanese 'Co Prosperity Sphere' fell apart over the course of 1940 and 1941. Japanese naval power had taken a shattering blow, and damage to the home islands was sufficiently devastating there was sufficient public disillusionment that the grip of the military government in Tokyo became too shaky to dare risk war with even a damaged USA. In early 1942, the Japanese military government fell, and Japan fell into a state of semi-chaos for several months.

The occupied territories reacted in varying ways, most of them were themselves heavily damaged, in some areas Japanese occupying forces were ousted, in some they hung on, in some they were forced into semi-alliance with their subject populations. Asian politics was scrambled beyond recognition and would remain so for decades.

The USA, likewise, was reeling. Though the damage was less, as a percentage of the whole, than for Japan, the west coast was in semi-ruins. Insurance companies went broke, stocks plummeted, and the Great Depression, which had been gradually lifting, returned in force. FDR found himself hamstrung, both politically and economically, in his efforts to quietly aid the British, and the emerging Anglo-American alliance basically fell apart.

Facing Germany without significant American aid, and with her empire damaged by the Event as well, and increasingly strangled by submarine warfare, Britain was forced into a cease-fire with Germany by the end of 1942.

To be continued...

AlexanderHowl · 06-18-2019, 10:47 PM

La Palmas is actually a much more likely (and much more dangerous) tsunami threat. The figures that I have seen have been 50 meter tsunamis hitting the East Coast when La Palma finally goes. The Big Island is a shield volcano, by the way, so it really cannot generate the landslides required for such tsunamis.

The La Palma scenario in 1940 would remove the USA from being part of WW II. Boston, Providence, New York City, Miami, etc. would be wiped off the face of the Earth, and the tsunami would hit seven hours after the eruption. It is likely that it would outrace any warning and, even if it did not, the authorities could not evacuate the Atlantic coast cities in just seven hours. With 1/4 of its GDP erased and a good 1/8 of its population dead or displaced, the USA would have been on its knees.

The Japanese could have easily taken the Philippines, Indonesia, and Australia without worrying about the US Navy because every ship would have been sent to the East Coast to help with the recovery. The USSR and the UK would not have had US assistance, meaning that Germany would have had a much easier time of it. The UK would have likely sued for peace by 1942 while the USSR may have been driven back to the Urals by the Germans by 1942.

Rysith · 06-18-2019, 11:09 PM

Quote:

Originally Posted by AlexanderHowl

The Japanese could have easily taken the Philippines, Indonesia, and Australia without worrying about the US Navy because every ship would have been sent to the East Coast to help with the recovery. The USSR and the UK would not have had US assistance, meaning that Germany would have had a much easier time of it. The UK would have likely sued for peace by 1942 while the USSR may have been driven back to the Urals by the Germans by 1942.

But that's not what the goal of this world is - it seems like the goal is to end up with an aborted WWII and a series of uneasy peaces an instability around the world in it's wake. The UK and Germany are unlikely to be friendly despite the cease-fire, the United States and Japan are unlikely to be friendly in the Pacific despite their lack of open hostilities, and the German invasion of the USSR is probably even more bloody than it was in our timeline, and is probably ongoing.

In short, a much more interesting world to get up to two-fisted adventure shenanigans in than a world in which the major conflicts have been largely settled.

Michele · 06-19-2019, 02:54 AM

Quote:

Originally Posted by Rysith

But that's not what the goal of this world is - it seems like the goal is to end up with an aborted WWII and a series of uneasy peaces an instability around the world in it's wake.

...

In short, a much more interesting world to get up to two-fisted adventure shenanigans in than a world in which the major conflicts have been largely settled.

True, true... It's just, I don't know, I somehow always feel dissatisfied with this kind of act-of-God divergences. A personal preference.
That said, I have no objections to the timeline; based on the initial assumption, it's realistic.

dcarson · 06-19-2019, 03:03 AM

I remember reading about Hawaii and landslide created tsunamis. A bit of googling found

Quote:

Hawaii has its own history of mega-tsunamis, most recently about 100,000 years ago. “One block of rock that slid off Oahu is the size of Manhattan,” wrote Becky Oskin in Live Science.

https://www.theatlantic.com/science/...sunami/411970/

So possible.

adm · 06-19-2019, 06:21 AM

Quote:

Originally Posted by Johnny1A.2

... the west coast was in semi-ruins. Insurance companies went broke, stocks plummeted, and the Great Depression, which had been gradually lifting, returned in force....

Pre-World War Two, this would be a somewhat minor set back for most of the West Coast, most of the industrial build was after Pearl Harbor, and was both a move to shield industry from possible NAZI attacks, and to move production closer to the Pacific front.

The tendency for the west coast to have sea side cliffs will limit inundation, and will largely limit the damage to harbors and ports, the biggest hit would likely be the loss of Southern California oil with damage to the Long Beach port facilities.

malloyd · 06-19-2019, 08:36 AM

Quote:

Originally Posted by adm

The tendency for the west coast to have sea side cliffs will limit inundation, and will largely limit the damage to harbors and ports, the biggest hit would likely be the loss of Southern California oil with damage to the Long Beach port facilities.

Thought the good harbors tend to be in the places with shallow bottoms, and hence more vulnerable to tsunamis. Deep water shores tend to abrupt transitions that don't have much in the way of a ridge further out for a breakwater.

But no, I wouldn't expect the damage to be really bad for the US. Most megatsunami scenarios tend to be pretty exaggerated, except for a really local event, or an asteroid impact that's going to present a lot worse problems than a wave, damage is not going to stretch more than a dozen miles inland. Yes humans like coasts, so that's a major disaster, but there aren't many nations where losing everything within a dozen miles of half your coastline is going to be crippling.

Actually I don't even think it makes sense for it to worsen the depression. The reverse if anything - depressions after all result from people not working, and a major disaster means a lot of demand to rebuild or replace stuff.

I'll concede the east coast of Japan is in bad shape, but I'm not so convinced the naval losses are that horrible. Tsunamis aren't all that fast, and this is an era that does have lightspeed communications, so even nothing comes in from Hawaii, once the wave starts hitting the first Japanese possession with a radio they know something is happening, and you don't need to get ships too far off shore to protect them. Nor do you need to get the key government officials that far inland to keep them alive. Launching a major new war is probably off the table for a decade or two, but I expect they have enough of a government and navy left the Empire isn't going to outright collapse. One issue to consider for the impact in mainland Asia is that the Japanese focus there is mostly in Korea and Manchuria, and those areas are shadowed from the wave by the Japanese islands themselves and are presumably even more critical to Japan now.

The Colonel · 06-19-2019, 10:46 AM

Unless I'm missing something, most of the places occupied by Japan in 1940 were in China weren't they? Granted the Tsunamis cited would scour the Pacific Islands of life and probably do a lot of damage to Tokyo... but still not sure that they'd achieve the results expected of them.

adm · 06-19-2019, 10:56 AM

Quote:

Originally Posted by malloyd

Thought the good harbors tend to be in the places with shallow bottoms, and hence more vulnerable to tsunamis. Deep water shores tend to abrupt transitions that don't have much in the way of a ridge further out for a breakwater.....

Good harbors on the west coast of the United States really aren't that common, LA has a semi-protected notch on the coast, with a man made mole to shelter it from waves. San Diego is a bit better. "Real" harbors are pretty much limited to Puget Sound, and San Francisco Bay.

capnq · 06-19-2019, 05:39 PM

Quote:

Originally Posted by AlexanderHowl

La Palmas is actually a much more likely (and much more dangerous) tsunami threat.

Sounds like you've discovered Tsunami-2.

06-18-2019, 10:07 PM	#1
Johnny1A.2 Join Date: Feb 2007	Tsunami-1 This time line superficially appears to have diverged from Homeline's path on July 19 1940. However, Homeline geologists argue that the actual divergence point would have to have been centuries earlier, with the effect becoming manifest on 19 July 1940. Either way... 1940 - Mauna Loa, the largest (in volume) volcano on the Big Island of Hawaii, began erupting in April, just as it did on Homeline. However, unlike Homeline (and our world), the dormant neighboring volcano, Mauna Kea, also began to display a certain amount of limited eruptive activity, in the form of cinder cone eruptions. The joint activity continued throughout April, May, and into June, and at this point Kilauea began to erupt as well. The cinder cone eruptions around the peak of Mauna Kea were not particularly problematic, but the lava effusions from Mauna Loa and Kilauea were another matter, becoming serious threats to life and property in some areas. By this point, the Hawaii Territory was in a state of emergency and panic was beginning to set in in some quarters. Assistance was marshalled to help with locals and ships were prepared against the possibility of evacuations. War tensions, at least locally, receded somewhat in the face of the geological issues. On 19 July 1940, however, events outran all preparations. Massive earthquakes originating under Mauna Kea appeared to trigger answering tremors under both Mauna Loa and Kilauea...and a large slab of the Big Island slid into the ocean. The devastation in the Hawaiian Islands proper was near total. Immense tsunamis raced outward across the Pacific, bringing devastation to the western coastal regions of North and South America and throughout much of the eastern coasts of Asia. Australia was affected heavily, and much of the Dutch East Indies were devastated as well. The world was stunned both by the unexpected geological calamity and by the devastation the immense waves generated. Among the effects were the near-total destruction of much of both Japan and America's Pacific naval power. The American Pacific Fleet had been advance-stationed at Pearl Harbor two months before the Event, and most of it was destroyed. Not that it would have made much difference had it remained in San Diego, because San Diego was also devastated. Along with the loss of ships, even more damaging in some ways was the loss of critical shore support facilities. (Indeed, those ships out in the open sea were scarcely affected.) The Pearl Harbor attack was wiped from history, and indeed the damage from the Event was sufficient that the Japanese 'Co Prosperity Sphere' fell apart over the course of 1940 and 1941. Japanese naval power had taken a shattering blow, and damage to the home islands was sufficiently devastating there was sufficient public disillusionment that the grip of the military government in Tokyo became too shaky to dare risk war with even a damaged USA. In early 1942, the Japanese military government fell, and Japan fell into a state of semi-chaos for several months. The occupied territories reacted in varying ways, most of them were themselves heavily damaged, in some areas Japanese occupying forces were ousted, in some they hung on, in some they were forced into semi-alliance with their subject populations. Asian politics was scrambled beyond recognition and would remain so for decades. The USA, likewise, was reeling. Though the damage was less, as a percentage of the whole, than for Japan, the west coast was in semi-ruins. Insurance companies went broke, stocks plummeted, and the Great Depression, which had been gradually lifting, returned in force. FDR found himself hamstrung, both politically and economically, in his efforts to quietly aid the British, and the emerging Anglo-American alliance basically fell apart. Facing Germany without significant American aid, and with her empire damaged by the Event as well, and increasingly strangled by submarine warfare, Britain was forced into a cease-fire with Germany by the end of 1942. To be continued... __________________ HMS Overflow-For conversations off topic here.

06-18-2019, 10:47 PM	#2
AlexanderHowl Join Date: Feb 2016	Re: Tsunami-1 La Palmas is actually a much more likely (and much more dangerous) tsunami threat. The figures that I have seen have been 50 meter tsunamis hitting the East Coast when La Palma finally goes. The Big Island is a shield volcano, by the way, so it really cannot generate the landslides required for such tsunamis. The La Palma scenario in 1940 would remove the USA from being part of WW II. Boston, Providence, New York City, Miami, etc. would be wiped off the face of the Earth, and the tsunami would hit seven hours after the eruption. It is likely that it would outrace any warning and, even if it did not, the authorities could not evacuate the Atlantic coast cities in just seven hours. With 1/4 of its GDP erased and a good 1/8 of its population dead or displaced, the USA would have been on its knees. The Japanese could have easily taken the Philippines, Indonesia, and Australia without worrying about the US Navy because every ship would have been sent to the East Coast to help with the recovery. The USSR and the UK would not have had US assistance, meaning that Germany would have had a much easier time of it. The UK would have likely sued for peace by 1942 while the USSR may have been driven back to the Urals by the Germans by 1942.

06-19-2019, 10:46 AM	#8
The Colonel Join Date: Jul 2006	Re: Tsunami-1 Unless I'm missing something, most of the places occupied by Japan in 1940 were in China weren't they? Granted the Tsunamis cited would scour the Pacific Islands of life and probably do a lot of damage to Tokyo... but still not sure that they'd achieve the results expected of them.