Dwarf Fortress Bug Tracker - Dwarf Fortress
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0001339Dwarf FortressCave-inspublic2010-04-19 11:372014-08-26 12:35
normalminorhave not tried
0001339: Plants grow in "Muddy Open Space", resulting in occasional cavern collapses
Dunno if it is a bug or feature...
every couple of months in my current fortress I have cavern collapses in the cavern layers 1-3 deep underground (~level 10-20).
Asmy dwarves sealed offall entrances as soon as they broke through the caverns (more than 1.5 years ago) and never dug into the cavern levels afterwards I assume it has nothing to do with the digging and building of my dwarves.
(unless of course it is a feature and the cavern collapses happen because of static instabilities, caused by shifting pressure from above, due to my mining and building)
I had it 1-2 times in around 6 fortress foundings, so I assume it is a little bit random.
Maybe related to "cavern collapse upon embark"
cave-in, collapse
related to 0007533resolved Toady One Phantom "Something has collapsed on the surface" reports, related to tree growth/chopping 
has duplicate 0002471resolved Footkerchief Fungiwood grows in midair 
has duplicate 0002594resolved Footkerchief Small cave ins when I load 
has duplicate 0000590resolved Footkerchief Cavern Collapse on load 
related to 0000127new  Muddy open space in magma pipe 
related to 0001503new  Water fall into lava creates endless 'cavein' messages 
Issue History
2010-04-19 11:37ProteusNew Issue
2010-04-19 11:42FootkerchiefNote Added: 0004256
2010-04-19 15:30ProteusNote Added: 0004271
2010-04-19 15:33ProteusNote Edited: 0004271bug_revision_view_page.php?bugnote_id=0004271#r1429
2010-04-22 05:10ProteusNote Added: 0004574
2010-04-22 10:30FootkerchiefIssue Monitored: Footkerchief
2010-04-22 10:32FootkerchiefNote Added: 0004616
2010-04-22 10:32FootkerchiefRelationship addedchild of 0000051
2010-04-22 10:33FootkerchiefNote Edited: 0004616bug_revision_view_page.php?bugnote_id=0004616#r1577
2010-04-22 13:55ProteusIssue Monitored: Proteus
2010-04-22 13:55ProteusIssue End Monitor: Proteus
2010-04-22 14:45ProteusNote Added: 0004635
2010-04-22 14:47ProteusNote Edited: 0004635bug_revision_view_page.php?bugnote_id=0004635#r1581
2010-04-22 14:52ProteusNote Edited: 0004635bug_revision_view_page.php?bugnote_id=0004635#r1582
2010-04-22 14:58smjjamesNote Added: 0004636
2010-04-22 15:12KennelTag Attached: cave-in
2010-04-22 15:12KennelTag Attached: collapse
2010-04-22 15:14ProteusNote Added: 0004638
2010-04-22 15:16smjjamesNote Added: 0004639
2010-04-29 13:18FootkerchiefCategoryDwarf Mode -- Environment => Cave-ins
2010-05-21 21:59o_OWTFaceNote Added: 0007159
2010-05-21 22:01o_OWTFaceNote Edited: 0007159bug_revision_view_page.php?bugnote_id=0007159#r2674
2010-05-28 23:33immibisNote Added: 0007462
2010-05-29 00:17FootkerchiefNote Added: 0007463
2010-05-29 00:18FootkerchiefRelationship addedrelated to 0000127
2010-06-20 09:25FootkerchiefRelationship deletedchild of 0000051
2010-06-20 09:25FootkerchiefRelationship replacedchild of 0000127
2010-06-25 13:27FootkerchiefSummaryRepeated cavern collapses every couple of months without dwarven interference => Plants grow in "Muddy Open Space", resulting in occasional cavern collapses
2010-06-25 13:28FootkerchiefRelationship addedhas duplicate 0002471
2010-07-14 11:40FootkerchiefRelationship addedhas duplicate 0002594
2010-08-18 16:36Logical2uRelationship addedrelated to 0001503
2012-02-22 08:23FootkerchiefRelationship replacedrelated to 0000127
2012-03-06 07:59FootkerchiefRelationship addedhas duplicate 0000590
2014-08-26 12:35FootkerchiefRelationship addedrelated to 0007533

2010-04-19 11:42   
It's not static instabilities. The likely culprit is magma and water mixing, causing floating chunks of obsidian that instantly collapse.

Does it reproduce if you regenerate the world and embark on the same location? If so, it would be helpful if you posted the parameters you used to generate the world, and a screenshot of the exact embark location.
2010-04-19 15:30   
(edited on: 2010-04-19 15:33)
O.K., I will do it, although it might probably take till wednesday (it takes around 5 hrs to generate the world, so I have to do it when I don´t need him for this time).

As for your assumption...
what I can definitely say at the moment is,
that at least in one of the cave-ins water was involved (it happened at the location of an underground lake in the northern caverns)
and in another case magma (happening at the great magma lake in the south of the map [and leading to the discovery of adamantine])
(not sure about the other collapses...either not visible, of happening without magma and/or water to be seen)

2010-04-22 05:10   
I regenerated the world with thesame seed (and attributes)
and went to found a fortress at the same location,
but wasn´t able to recreate the recurring caveins.

The party got an initial cavein upon arrival at the location,
but till they died from acid rain at the end of summer they didn´t get any additional cavern collapses.
A 2nd party that went to reclaim the fortress also got a cavern collapse at arrival, but even after a year they didn´t experience another cavern coillapse
(at this time my original fortress already had experienced 1-2 additional cavern collapses.

I assume that maybe the first cavern collapses upon arrival had to do with it, maybe it happened at another location in the original fortress than at any of the other fortresses, therefore freeing a flow of magma (or water) that was blocked in the other fortresses.

A srange thing that I experienced upon reclaiming (and kmaybe another bug) is, that in the reclaimed fortress all mud in the caverns had vanished. There was not a single tile of muddy cavern floor to be found anymore (where the original fortress had lots of muddy floors in the cavern), only naked stone.
2010-04-22 10:32   
(edited on: 2010-04-22 10:33)
Hmm... well, if you got a reproducible collapse at arrival, the world gen parameters + embark location screenshot could still be useful for tracking down 0000051.

The mud disappearing on reclaim is another known bug, 0000133.

2010-04-22 14:45   
(edited on: 2010-04-22 14:52)
O.K., here we are:
http://www.youshare.com/Guest/a73100/DisplaySimple [^]

The first rar file contains the location of the fortress (eastern rim of the region) as well as the txt-file with all world parameters. including seed (i changed a few parameters from default like end year (which is 1200) and max cave size ... might be impotant for you to know)

I also made a backup of the original fortress (so that I could continue with playing with it again, after completing all the test runs).
I have uploaded it as well as the 2nd rar-file (regon1.rar)

It may be a bit big (73 MB), but it contains the recurring caveins I spoke about (upon playing it again from this savefile I encountered 2 additional ones till mid spring of the next year)

2010-04-22 14:58   
Have you tried to dig towards the source of the recurring caveins? There is a zoom to event function on the announcements screen which will help with that. I posted on a report similar to this (one of the stickies) that I had one in a fort when I embarked and homed in on the spot by digging downwards and it wasn't real long before I found the cause.

I realize some spots may be inaccessable due to magma or water, but you can always dump a cow or something down there. :)
2010-04-22 15:14   
They happen at several different places,
the past ones mostly in caves that were visible(without a visible cause however)
the 2 ones I spoke about (which I got shortly after reloading the save I posted) however in the undiscovered regions of the caverns.

I never got to discover a cause to them from what I saw...
some happened above normal cavern floor, some above water (there is a lot of water in the caverns) and 2 above the magma pool (with the last cavein above the magma pool leading to the discovery of adamantine)
2010-04-22 15:16   
Sounds like DF reveal would be of HUGE help here, despite the fact that it is known to break stuff.
2010-05-21 21:59   
(edited on: 2010-05-21 22:01)
I may have figured it out. "Muddy Open Space" appears and when a plant starts growing in it, the whole thing collapses. What exactly allows empty space to be muddied isn't clear, but flying creatures and erosion are good guesses. If it matters, I modified my worldgen cavern generation significantly.

I can upload a save to DFFD and point this out, if anyone wants.

2010-05-28 23:33   
It would be a very good idea to upload a save, yes.
2010-05-29 00:17   
I may have figured it out. "Muddy Open Space" appears and when a plant starts growing in it, the whole thing collapses.

Oh, interesting. That suggests a link to 0000127.