Simply put, what forces of nature would cause a volcano to erupt on a seasonal basis? Say it does not do anything 9/12 months, but it becomes very active for three months and often erupts. I would like it to be a visible eruption (No Phreatomagmatic eruptions, please).

Any form of eruption is acceptable, but explosive eruption is preferred. I have several moons that can act as a catalyst, providing tidal forces that cause the said volcano to erupt a la the Jovian moon Io.

I am still learning to post properly, so forgive me for any errors. Please point them out as they appear.


4 Answers 4


You said it already: tidal forces caused by an eccentric orbit, which brings the moon closer to the planet only for 1/4 of the orbital period, causing therefore deformation in the crust and increased volcanic activity all around.

  • $\begingroup$ Well, yes, but I wish to find ALL the potentials I can use, not just one. Expand my knowledge. $\endgroup$
    – Rory 02
    Commented Mar 31 at 5:08
  • 1
    $\begingroup$ @Rory02 There is pretty much no other reason. $\endgroup$
    – Monty Wild
    Commented Mar 31 at 6:06
  • $\begingroup$ Well then. That settles that. I accidentally found the answer. Thank you! $\endgroup$
    – Rory 02
    Commented Mar 31 at 6:33
  • $\begingroup$ @Rory02 in addition, we normally do not brainstorm here. We work on a best answer principle. Asking a question can of course lead to new insights or other ideas, but asking a question for just new ideas is frowned upon. $\endgroup$
    – Trioxidane
    Commented Mar 31 at 20:22

It is believed that some volcanoes on Earth have seasonal variation in their activity (though there are many other factors too). As I understand it, the driving force for this is differences in tropical/monsoon rainfall; heavy rain increases the loading on the rock and acts (with some time delay?) as a lubricant and source of steam for the magma. (The processes involved are complex, and are definitely outside my expertise!)

Given that seasonal variation exists in reality (albeit at a statistical level), accentuating it in your constructed world is fine. Assume there is a mechanism by which it can be explained, and try to avoid going into the details.

  • $\begingroup$ I thought I had to explain everything. Huh. Can I really just go ahead and not talk about all the details? $\endgroup$
    – Rory 02
    Commented Apr 1 at 11:35
  • $\begingroup$ Yes, you always have the option of not talking about it, or at least being superficial. Your audience will enjoy internal consistency, but that doesn't mean you spell it out in every detail. Also consider that your characters might not understand it either, or might have to lean it over time. (Maybe even getting it wrong at first.) Or maybe they just take it for granted. -- still, it's good if you take time to understand how it should work and what the consequences are, as it can enhance the story if used right. $\endgroup$
    – Brianorca
    Commented Apr 2 at 18:40

Cold / Ice

Perhaps the volcano is active throughout the year, but the freezing season blocks the exit of the volcano by condensation and ice of some form (need not be water, could be anything depending on chemistry of the planet).

The blockage actually causes greater risk, by increasing the pressure build up. Basically creating a ticking bomb.

So during these times, it erupts, catastrophically, at indeterminate times without warning.

During the summer months, the lava flows and gasses exude. But it's a streamlined flow. Fizzing, and purring, vigorously and magnificently, but not exploding.


Your timings match. Say this planet has 6 summer months and six DARK winter. After the freezing and ice blanketing starts in the middle of the year, it will take some time for the pressure to build up. So you have some eerily quiet few winter months culminating in kabooms. Then, when the summer sun sets in again, it's all thawed, and there's not many explosions.

  • $\begingroup$ Neat. So, theoretically, if I had a planet like Neptune where it is on its side rolling about, this scenario would fit quite well? $\endgroup$
    – Rory 02
    Commented Apr 1 at 11:34
  • $\begingroup$ Note that subglacial eruptions look quite different from what most people expect from a volcano. Ice quickly absorbs the heat from lava and eruptions are likely to manifest as meltwater and debris floods instead of a lava outflow. $\endgroup$ Commented Apr 2 at 9:03

Do the eruptions need to be causally related to the seasons, or can they just coincide?

The simplest answer is that it takes around a year for enough pressure build-up in the volcano to cause eruption. This has no relation to the seasons at all, its simply due to the volume and diameter of the magma tubes below.

It just so happens that the volcano starts puttering around the time winter ends, and the final eruption is around the first day of summer, but those two things are not really meaningfully related.


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