If your black friend is unavailable, an 18 year old blond girl with a loose blouse and a deer-in-the-headlights look on her face will do in a pinch. Make sure she knows how to look from side to side while simultaneously saying “Hello? Is anybody there?”.
It would be easier to make a guess if we knew a little more about the topology and geology of your lot. What I suspect in this case is maybe a construction-materials building pit that lies in a drainage path. Water has been flowing under it and undermining it, and now it’s starting to collapse. We’ve had some unfortunate folks in our neighborhood who have found these beneath their foundations :eek: and had to do an ungodly amount of structural stuff to keep their houses from leaning to the side.
I am curious if the hole is damp, if it has changed sizes, how old the house is and if you’ve tried filling it with dirt. The hole, that it. 
It’s not damp, and hasn’t gotten any bigger. The swirled depression in front of it is progressing to a hole of it’s own- it’s definitely sinking. The house is an old adobe and cinderblock built in the 40’s, I think. I have not tried filling it with dirt- because 1)I don’t have any 2)I’ve have my hands full cleaning up my patio (beside the hole) because, when it rains like it’s been doing lately, there’s a giant layer of dirt and gravel that is deposited onto it every time and 3)it’s freaking hot out there. I suppose I could fill the hole with the dirt from my patio if necessary. But really that’s where maintenance comes in- the whole hole thing needs to be fixed by them. There are advantages to renting, and this be one of them.
I’m guessing Cosmic Relief is right- we’ll see.
Beam down a team of Red Shirts to check it out…
Actually, have you tired probiong it with a suitable scientific instrument, like a stick? Is it hollow underneath or firm?
Does it freeze hard in your area (Please forgive my Canadian ignorance)? We get things that look like that called “ice wells” that are a result of a small amount of underground water freezeing, loosening compacted soil as it expands, and then collapsing once the ice melts…
Just a guess…(if it freezes in your area during winter)
FML
This looks very similar to sinkholes which form over underground voids. As Cosmic Relief says, sometimes buried construction debris causes this - when some of the buried things rot away (wood, cardboard, paper), a void is left and the ‘crust’ above it sinks in.
Another cause of underground voids is when groundwater follows along something hard underneath the ground - such as a tree root, underground cable, or underground pipe (as 3acres mentioned). As the groundwater moves through the soil, it carries some soil with it. This can create a void over time.
In other cases there is an underground pipeline with a hole or crack in it, which is allowing groundwater to seep into the pipe. Again, as the water moves through the ground, it takes soil with it, and a void is created.
The fissures I’ve seen are due to the ground cracking because of drought conditions. The moisture is dried out of the soil and it cracks open - like a muffin or cake cooked too long in the oven.
Let us know what your landlord says. I hope he/she doesn’t try to tell you it’s “nothing to worry about”.
That shouldn’t be an issue it the house was built in the 1940’s, should it?
Would it not be wet in either of those cases?
I got nothin’.
Maybe so. I was speaking of voids in general - that sometimes they’re caused by buried debris. Perhaps in this case something which takes 40 years to decay? 
Not necessarily. Groundwater can be intermittent, just like above-ground streams.
Actually, I like your suggestion to fill it with dirt. If it’s something severe, it will come back. Filling with sand or dirt might tell the tale.
Aww dammit! Pastels, swatches, big hair, leg warmars and Ronald Reagan all over again!
Tarantulas want only one thing during the monsoon and you will have to provide it sooner or later. They always win. Denying them is hopeless and maddeningly brutal.
They want your teenagers.
It is obvously a Bigfoot foot print. Get some plaster of Paris stat!
Answer: According to Willy the maintenance man, who speaks limited English to go with my limited Spanish, the hole is an old septic tank site. He says there used to be a concrete slab under the dirt, but he doesn’t know what happened to it. Two years ago he filled it in, and now it’s caved in again. He filled it today, I will keep an eye on it, and no tarantula or Cthulu sightings to date.
Thanks for playing!
What about a poo monster? Can’t be too careful with poo monsters. There used to be a concrete slab, and now it’s vanished? :dubious:
I know! But you have to take what Willy says with a grain of salt- he’s old. That was probably another house he was thinking of, or something. I also came home to find that my landlord has, without notice to me, installed another shed in my backyard, taken down most of the wood privacy fence, and is now planning on cutting my backyard in half, putting up a chain-link fence, and using the back half of the yard for his storage shed. I am not too happy about this. I wasn’t using the whole backyard, as it is huge, so that’s okay I guess, but chain link doesn’t even give me any privacy from my very close neighbors! Grrr! Guess I can’t walk around naked in the backyard even if I wanted to, now! A little notice would’ve been nice!
Willy lies. His “limited English” is due to his fluent knowledge of ancient Arabic, and it has driven out all concepts of freedom and independence in his mind. He has truly studied his Necronomicon, and is heralding the coming of the Elder Gods.
He is the Maintenance Man of the Apocalypse.
So, “filling it” was suggested by Moi.
Do I win a cookie, an old fence or Willie on my answering machine?
Oh come on. Everyone knows that the Necronomicon was buried in a small golden casket at the laying of the foundation of an adobe house somewhere in Arizona some sixty years ago. :rolleyes:
You win the movie Van Helsing. Or a surly teenaged boy. Your choice!
I was concerned that if I filled it, and there was a leak or something bad happening in there, it would make it harder to diagnose and something worse would happen.
Plus, you know, it’s hot.
It’s probably a portal to Hell. Make sure you tell Satan when he needs to have that DVD back to the video store
No, can’t be- my front door is the portal to hell. There wouldn’t be two portals to hell in such close vicinity to each other, would there?