Apocalyptic Events, Super Volcano's, Gravity and Humanity...

[Malanath]

I need a bit of help from the more scientifically (and mathematically) inclined.

In a Fictional World that is roughly 25% larger than Earth what would gravity be like? How would it effect the height of creatures living there? I remember reading (or watching something) about the effects of Gravity on Humanity in different climates. For example, in a world with less gravity than Earth Humans would tend to be taller, and in a world with more gravity than Earth they'd be shorter. Of course, there are some places where gravity would basically crush you into non-existence from the pressure and other places where if you'd jump you'd be thrown into Orbit around the planet (if not enough gravity).

Alright, the Fictional World is 25% larger than Earth. That means it has more gravity. Now let us say it has a moon slightly larger than our own in proportion to the size of the fictional planet (roughly 35% larger than our own moon). This means waves and volcanoes would be rather active from the gravitational force exerted by the Moon.

Let us now say that there are Super Volcano's on this planet and one of them erupts with roughly 3 times MORE force than Toba did on Earth 75,000 years ago... This would, naturally, cause death on a massive scale and be an Apocalyptic Event. The planet would be thrown into a Volcanic Winter for a period of time. Vegetation would die... Anything even REMOTELY near the site of the explosion would be just completely gone. There would be nothing left of the site but a massive crater so large it'd be clearly visible from space (maybe even the moon?).

I would think that such an explosion with so much force would cause the planet's axis to tilt AWAY from where the explosion happened. Would such a dramatic tilt cause the planet to be thrown out of orbit (sending it hurling into space, toward it's own moon, or into the sun?) Also would it be possible for the explosion to be so massive that it actually hurls dust and ash into space which would form ring-like bands around the planet?

What would happen to such a world, and what would be the likelihood of civilizations surviving (non-technically advanced with very little to no magical or godly aid), assuming that they existed on a continent roughly the size of South America?

If the fictional world was lucky and had a few thousand humans surviving, roughly how long would it take for them to replenish the population (to about 100 million humans) taking into account the Volcanic Imposed Ice Age?

 

[Malanath]

Some other things:

If such a volcano would explode with such force would it be unreasonable to believe that there would be a chain-reaction around the entire planet? Meaning, that it would most likely cause worldwide earthquakes, floods, and even other active volcanoes to erupt? Any underground races would be in serious danger both from the earthquakes and possible magma bubbling up from the planets core.

Races living above ground would face other threats which would be just as deadly. For one those that didn't die in the initial explosion would die in the aftermath. They would inhale the tons of ash and small bits of debris falling from the sky. There would be so much ash and debris falling (and it being FAR worse if the other Volcano’s on the planet went off in a chain reaction effect) that the entire planet's surface would be blanketed in ash. Inhaling ash is deadly and is what kills most people in Volcanic Eruptions. I think the magma would be a more serious threat to those living underground than those living on the surface.

There would also be acidic rain... I've read that sometimes when Volcanoes explode that it causes it to rain. The rain would be poisonous and acidic...

I have no idea what would happen to tectonic plates... they would most likely shift I would think. It might even rip entire continents apart...

 

[Turanil]

Let us now say that there are Super Volcano's on this planet and one of them erupts with roughly 3 times MORE force than Toba did on Earth 75,000 years ago...

I would think that such an explosion with so much force would cause the planet's axis to tilt AWAY from where the explosion happened. Would such a dramatic tilt cause the planet to be thrown out of orbit (sending it hurling into space, toward it's own moon, or into the sun?)

What would happen to such a world, and what would be the likelihood of civilizations surviving

I did read a book on planets, very interesting. So, remembering what I did read of it I will say:

-- A few millions of years there were volcanoes that compared to those existing today were (according to a scientist) "like a nuclear bomb compared to a firework cracker" (or maybe just dynamite compared to a firework cracker? ). In any case Earth did have volcanoes and eruption of epic disaster sizes, and proto humans still survived (with a smaller brain) and let the way down to us. Obviously our planet wasn't thrown out into space towad the moon or the sun.

-- With gravity 35% higher, all living beings would be shorter and smaller, and mountains would be less high.

 

[Malanath]

According to some of the sources I've read:

"The last known explosion of what might be considered a super volcano was Toba in Indonesia. Toba erupted with a huge explosion about 74,000 years ago. The force of the explosion was estimated to be 10,000 times more powerful than the blast that destroyed Mount St. Helens, in Washington.

Tremendous amounts of rock and ash were ejected into the air, blocking the sun for months. The temperature around the globe was thought to have plummeted as much as 21 degrees. Man was pushed to the edge of extinction, the population forced down to just a couple of thousand. Perhaps as much as 75% of plant life on the North American continent may have died out."

"Magma would be flung more than 50 kilometres into the atmosphere. Within a thousand kilometres virtually all life would be killed by falling ash, lava flows and the sheer explosive force of the eruption. Volcanic ash would cover places thousands of miles away. One thousand cubic kilometres of lava would pour out of the volcano itself, enough to coat the whole of the USA with a layer a few inches thick. ... Within minutes of the eruption tens of thousands could be dead.

The long-term effects would be even more devastating. The thousands of cubic kilometres of ash that would shoot into the atmosphere could block out light from the sun, making global temperatures fall dramatically. .... Effects world wide would cause massive food shortages."

Alright, multiply that by about three or five. What would be the result?

 

[kigmatzomat]

Here's some things to consider:

size does not directly control gravity. Gravity is a function of the planet's total mass and distance to the center of the planet. You can have huge fluctuations in planetary size without impacting the force of gravity at the surface. Similarly, planets of a fixed size can have widely varying gravities. In other words, you can fairly easily adjust the planet's size from 1/2 - 3x the size of Earth with no impact on gravity. Or, you can have an earth-sized object with 2/3 - 10x Earth gravity.

Volcanic explosions are in line with the planet's core, so they could adjust the planet's orbit but not it's tilt or rotational speed. Adjusting tilt or rotation would require a force that does not line up with the planet's core.

Regardless, adjusting planetary tilt/orbit would require absolutely staggering amounts of force. Truly cosmic amounts of force The earth is an object massing 5.9742 × 10^24 kilograms so to get any measurable change in the planet's orbit you would need something on the order of 1 x 10^10 tons of plutonium or about 2.5 x 10^5 tons of antimatter. Detonations this big would destroy the planet, blow off the atmosphere, and boil the continental crusts.

 

[WayneLigon]

As was said above, mass not size affects gravity. A planet the same size as Earth but with less gravity has lesser mass. There will be fewer metals. or the metallic core will be smaller. A planet smaller than Earth but with a much greater abundance of metals would have a higher gravity (and probably be very unaccomodating to humans because of all the heavy metals in the biosphere).

By 'other places' I assume you mean other planets; gravity does not vary significantly across a planet surface. There is no planet where the gravity is so low you'd be thrown into space by your actions; such a planet would have no atmosphere because there isn't enough gravity to hold it there. Also, it wouldn't be a planet-sized body; more like an asteroid.

I would think it would be very unlikely that any planetary force could create rings; enough dust and ash would have to be expelled to reach escape velocity (about 25,000 miles an hour for Earth; it will be more for your theoretical higher gravity planet), and those particles would still have to make it up through the atmosphere.

Also, the volcano would have to expel several gigatons of matter, all of it making it into space, to form visible rings. Something like the mass of the Moon.

Tremendous volcanos and such do cause very tiny fluctuations in our orbit but nothing that matters, and have nothing to do with the axial tilt. As was said before, the Earth was much more geologically active in the past and that didn't change our orbit all that much.

Now, having said that, what you might want to look into for your fictional world is the wonderful world of pseudoscience! There is a notion called a Great Pole Shift that posits that the planet crust can slip on the magma it floats on and shift around. Thus, tropical continents could suddenly find themselves in the arctic, etc.

 

[Ultrazen]

Alright, multiply that by about three or five. What would be the result?

As an educated guess, not much difference.

At those levels of power, orders of magnitude are usually what is relevant. Multiplication by 3 isn't very significant. Multiply by 10, maybe; 100, probably.

My understanding is that Mt. St. Helens erupted with a roughly 350 Megaton blast. Toba was something like 3,000 times that, so somewhere around 1,000,000 Megatons. Multiply by three or even five. Everything is still on the order of millions of megatons, and you get catastrophic global population declines for all cases.

As far as how long it took human population to reach 100,000,000 after toba... well... about 74,000 years....

Also, even with a larger moon, tidal forces are not necessarily stronger. Those forces depend both on the mass of the moon and how far away it is from the earth.

Um, could somebody make this an rpg-related thread?

 

[Tonguez]

Um, could somebody make this an rpg-related thread?

He already did

If the fictional world was lucky and had a few thousand humans surviving, roughly how long would it take for them to replenish the population (to about 100 million humans) taking into account the Volcanic Imposed Ice Age?

I'm not gonna go into the pseudo-science of super volcanoes throwing planets out of orbit etc etc but rather explore the re population problem.

We know that humans can adapt to some extreme conditions and provided it was far enough from the epicenter you might even get areas where enough vegetation and animals survie to support a viable population.

in New Zealand it has been estimated (based on DNA studies) that the fursat settlers comprised 20 women (unknown number of men) and that by 1830 (1800 years latter) the population was about 100,000. During this time their was at least 2 volcanic events which caused environmental devestation - so extrpolate from that

actually I am gonna comment on the science

I live in a volcanic region and despite predictions of acid rain etc arising from volcanic events the last 'major' ash eruption here occured in 1996 (it was tiny by historic standards but still threw up a cloud of ash). Anyway the ash actually increased soil fertility and helped to increase the clarity (cleanliness) of waterways (lakes and rivers) by binding suspended ssilt and sinking to the bottom. Thats nothing about the super volcano - but it is worth noting that volcanoes actually do have environmental benefits which might help the survivors

 

[Nyeshet]

By a factor of only x3 or x5? Not much difference at all. North America alone has suffered worse than that several times in the last few million years.

I just googled Super Volcano to see if I could find a few good articles I once read about such. One of the more 'end of the world' type articles out there is almost word for world similar to the first post: http://armageddononline.tripod.com/volcano.htm

Here's a more realistic view of the Yellowstone situation: http://www.unmuseum.org/supervol.htm

A few more realistic* articles
*(Okay, I'll admit the Discovery one is a little sensationalistic.)

http://dsc.discovery.com/convergence/supervolcano/supervolcano.html
http://www.solcomhouse.com/yellowstone.htm
http://www.livescience.com/forcesofnature/050308_super_volcano.html

Here's a nice image dealing with the major Yellowstone and Valles Caldera eruptions
http://www.livescience.com/images/050308_nm_volcano_yellowstone_02.jpg

Of course, if you want a true 'end of the world' type eruption, I suggest you look to the Siberian Traps. The result of that super-volcanic eruption (the greatest known in the last half billion years) was the Permian-Triassic extinction event: 90% of all marine life and 70% of all land life dead within - at most - less than 60k years (perhaps even as little as 8k years), and it took about 50k to 100k years for the world to begin true recovery (in terms of spread of plantlife, etc) . It is the single greatest extinction event known to human kind.

Of course, the continuous output of lava lasted for millions of years. It was only the start and the worst of it around the extinction period. Note also that there is evidence of a massive (ie: 200km wide) crator that seems to date to the extinction event. Many current scientists seem to agree that the extinction was the result of a double-whammy: massive volcanism combined with a major meteor/comet strike within a few centuries or millinia of each other.

Problem with this: no adventurers survive to deal with the problem. Or perhaps the adventurers are the only survivors. Only those brave and daring enough to seek a sheltering area and start anew in terrible conditions are likely to survive, perhaps.

http://www.absoluteastronomy.com/encyclopedia/P/Pe/Permian-Triassic_extinction_event1.htm

 

[Malanath]

Thanks for your replies guys. It's been a great help, especially the replies about how gravity works. The world I am creating is loosely based around Norse Mythology and the ensuing event that they called Ragnarok. It is basically a "this is what happened afterward" type post-apocalyptic world about 3,000 to 5,000 years later.

I wanted things to seem some what believable so I looked to hugely destructive events in nature that could (in theory to the non-educated) produce 'end of the world' type effects. I came upon the Super Volcano and began reading up on it, and it seemed to be the best fit for destruction on a global scale.

In regards to the planet's rings and comparative to the moon being blasted into space.... I believe I read some theories that have the moon coming from the Earth in it's very early days. (Like when the solar system was still young and the planets were still under constant bombardment from huge asteroids and other debris.) So I know it's possible, in some theories at least, to get that much stuff into space from an Earth like planet... although I seriously doubt there would be any survivors on the planet if it were caused by an asteroid or comet...

Anyway here is how the fictional world of Midgard and its Moon called Hecate look:
Midgard is roughly 25% larger than Earth with a slightly more severe axial tilt. The axial tilt is a few degrees different than Earth's around 25 or 26 degrees, comparative to the Earth's 23 degrees. It causes more pronounced seasons around the world. Midgard has roughly 48 Million square miles of surface land comparative to the 38 Million square miles of surface land on Earth. Gravity is about the same.

Hecate is roughly the size of Titan with an atmosphere and with gravity only slightly less than Earth's. The difference would be noticeable at first but you'd quickly adjust. The atmosphere is more thick and allows the moon to retain more heat. The Moon has roughly 10 Million square miles of surface land divided between two small continents; the rest is an ocean, which circles the entire moon.

Hecate is further away from Midgard than our Moon to Earth but they exert roughly the same amount of gravitational force as the Moon does to the Earth, and Earth to the Moon. Hecate does not revolve around Midgard and does not rotate, causing one side of it's surface to be bathed in light constantly while the other to be constantly bathed in darkness. There is one continent on each side roughly 5 million square miles each. The oceans are not as deep as they are on Earth but are suitably deep enough to create a hydrosphere.

Around 3,000 to 5,000 years ago there was a large eruption at the prophesied battle of Ragnarok that nearly wiped out all life on Midgard. The eruption was so large and powerful that it set off a series of events that caused worldwide Earthquakes so powerful that fault lines caused some continents to have huge chunks break off. Tsunami's ravaged most coastal areas eliminating all life. Multiple Volcanoes and several Super Volcano's erupted with such force that it expelled enough ash and dust through the atmosphere to create a small thin ring around the planet. The ash and dust that did not leave the atmosphere blanketed much of the planets surface (only a dusting in some areas), and blocked out the light from the sun so much that nearly 90% of all plant life on the planet went extinct and an Ice Age of epic proportions ensued. Global temperatures plummeted by nearly 30 to 40 degrees, and most life forms that managed to survive the Ragnarok were killed as a result of the Ice Age. As most of the planet turned into a giant ice ball traveling between the continents was made easier.

The setting will take place in the Western Hemisphere roughly 3,500 years after the event. The Western Hemisphere has two continents and an island chain made up of many small islands which together have about 14 Million square miles of land. Current climate is comparable to the climate found in and around North America. Current Human Population in this area is roughly between 100 Million to 200 Million.