Opinions on earthquake in ocean combat

[phallic khan]

i know the rules state no eefect in deep water, however, we know earthquakes cause tsunamis. so heres the question. do you rhink the spel could cause a tsunmi and if so how big and how long would it take to foem?

[Deadmoon]

phallic khan wrote:

i know the rules state no eefect in deep water, however, we know earthquakes cause tsunamis. so heres the question. do you rhink the spel could cause a tsunmi and if so how big and how long would it take to foem?

Tsunamis are created when large areas of the sea floor change elevation relative to each other in a process called subduction. The area of effect of the earthquake spell is highly localized, so no tsunamis.

[kyrt-ryder]

UNLESS the sea floor is within range of the spell because the caster is reeeeaaallly deep underwater.

Then the question gains some validity ;)

[Kazaan]

A tsunami doesn't really become a "big wave" until it reaches the shore. Out in deep water, it'll make a pretty sizable swell, but it won't be "crest-shaped". So even if you could reach the ocean floor with an earthquake spell, a tsunami capable of causing significant damage wouldn't be localized... it'd spread out from the epicenter until it reaches coastline. If you cast it at the coastline, well, that isn't a tsunami, it's just an earthquake on the beach.

[Deadmoon]

kyrt-ryder wrote:

UNLESS the sea floor is within range of the spell because the caster is reeeeaaallly deep underwater.

Then the question gains some validity ;)

I was assuming the spell would be cast at the sea floor. The description of the effects of the earthquake spell are not consistent with the sort of tectonic activity that creates tsunamis. Specifically, large tectonic plates push against each other building pressure. These are really large. Geologic faults are miles long. The area of effect of the spell is an 80 foot radius.

Tsunami Geology - What Causes a Tsunami?

Understanding Earthquakes and Fault Lines

[Peasant]

This is one of those cases where, as nice as an understanding of the science is, it isn't really relevant to the spell. Earthquake (the spell) achieves its effect without any regard to the physics of seismology or even physics in general. The idea of propagating effects, as flavorful as they are, is right out. Someone standing 81' from the epicenter experiences no effect at all and the nearest equivalent effect (on lakes) doesn't even create current or chop. Physics is watching this spell effect from the cheap seats.

There is also the matter of Tsunami (the spell) to consider. Even this higher level spell doesn't really simulate a proper Tsunami, which does not bode well for the secondary effects of the weaker spell. As the druids might say, magic is as nothing compared to the true power of nature.

That said, descriptions of unusual high tides on foreign shores following major arcane exchanges at sea would just be good fun. And if the target of your wrath is specifically sea floor structures in a localized area, it wouldn't be unreasonable to wipe them out with the standard effects of the spell, reskinned as a wave.

[Deadmoon]

I would not say that the a spell can never indirectly affect things outside its area of effect.

The Earthquake spell description specifies that where there are cliffs, the spell creates a landslide that travels as far horizontally as it does vertically. Suppose your cliffs are 200 feet high and you cast the spell at the top.

What would happen to your landslide as it approached the 80 foot radius limit of spell effect? Would the falling earth cease to exist? Would it stop falling, supported by the boundary of the 80 foot radius? What happens when the spell's duration is elapsed? Does the landslide "undo" itself and go back to being a cliff? Or does the cliffside tumble all the way down and remain a pile of rubble?

I would rule that the tremors last one round, the landslide caused by the tremors is permanent, and the top of the cliff is now at the bottom in the form of a pile of rubble.

Magic is weird, but I don't like it so weird that I have to entertain things like the alternatives listed above.

[Peasant]

That is an entirely reasonable spin on such effects, Deadmoon, but I might argue that magic and reason are hardly fast friends. It is at least plausible that a landslide caused by magic has nothing whatsoever to do with gravity. In that case it might miraculously stop on a dime at some impossible angle or even roll back up hill to reconstitute the cliff. Or it might do precisely as you said and satisfy our collective sense of verisimilitude. The outcome might be very different in a campaign which emphasizes powerful and wondrous magic.

Back on point a bit, I'm curious why the OP wishes to create a Tsunami in this fashion? As weapons go, you don't get a whole lot more indiscriminate than a natural disaster. Are you merely interested in the roleplay aspect of such dire consequences to a spell? Or perhaps you're hoping to engage in a bit of character assassination by implying that Bob the Wizard was responsible for the tsunami that wiped out Townville? Both could be quite fun without ever actually answering the initial question in a hard and fast fashion. Thank you for the mental exercise.

[rangerjeff]

Isn't there some sort of wave spell I'm thinking of? I'd as GM rule that the earthquake went off as a wave spell, wouldn't be all that destructive but should probably disorient everybody it hit for a round or 3. Could cause a couple boats to knock into each other and do some damage.

But tsunami? No. Unless the earthquake spell is about a million times more powerful than I understand it to be.

[phallic khan]

just thinking of inadvertant consequences to spell casting for flavor. i'd been thinking of the part in the wheel of time where the aes sedai cause a bunch of damage changing currents and winds to move their boat faster and its got me on a bit of a tangeant. thank you for the input.

[Grizzly the Archer]

Spells that have a wave or tsunami like effect, or can:

World wave
Tsunami
Conrol weather
Slipstream
Control Water

Ocean(water) domain ability- surge
Water Arcane school ability- wave

[gamer-printer]

Really if you set off an Earthquake spell while on the sea floor, even if the area isn't large enough to cause a tsunami, it will definitely cause the silt and sand to turn into a Solid Fog completely blinding everyone in the vicinity until currents/tides move it away. Probably not the effect you'd want, but certainly what would happen...

[Peasant]

phallic khan wrote:

just thinking of inadvertant consequences to spell casting for flavor. i'd been thinking of the part in the wheel of time where the aes sedai cause a bunch of damage changing currents and winds to move their boat faster and its got me on a bit of a tangeant. thank you for the input.

An excellent realm of inquiry! I had a very enjoyable campaign grow out of that sort of inadvertence. Someone used Call Lightning above a coal bed and the ensuing underground fires later made for a rather hellish cavern crawl.

[Gobo Horde]

Grizzly the Archer wrote:

Spells that have a wave or tsunami like effect, or can:

World wave
Tsunami
Conrol weather
Slipstream
Control Water

Ocean(water) domain ability- surge
Water Arcane school ability- wave

Add Raise the Deep from Aquatic sorcerer bloodline to that list.

[Grizzly the Archer]

True Gobo, but that ability is extremely limited in use and application, since it doesn't move out of the area. It's like being in a desert and raising the deep water under the sand and such up and out onto the surface. That's what that ability seems like, not actually creating a wave or something.

Still, it gets added to that list, however limited.