I am traveling the roads south of Markarth and I keep feeling what seems to be earthquakes, or more appropriately "Nirnquakes". At first I thought it was another dragon, so I looked around but there was nothing. So I thought nothing of it and kept on moving, but then it happened again...and again...and again. I am so intrigued by this, what is it? I've never really spent too much time searching around the southern end of the reach, but I think I am going to because it just struck me that this is one of the nicest, most mysterious parts of Skyrim. I've spent at the bare minimum 500hrs in Skyrim and this is the first time I've felt a Nirnquake. Has anybody else ever experienced these "Nirnquakes".

(If it is tied to a quest or something, please don't spoil it for me.)

Yes that area is prone to earthquakes. That one may be tied to a quest in Dawnguard now that I think of it.

Yes.

Seek and ye shall find...

If you have good subwoofers, you will occasionally hear/feel http://en.wikipedia.org/wiki/Bloop low frequencly rumbling as you roam around the Skyrim exterior.

There was also this one time where there was this loud-ass rumbling followed by violent screen shaking that just happened randomly while I was exploring The Reach. In my 400 hours of gameplay, this has only ever happened once. Not sure what it was.

Since the real-world term doesn't capitalize the E in Earth I'd assume that "earthquake" can also be used for fictional settings.

Wow, this is good to know.

It's actually Forsworn Rockslide traps. I know cause i heard what i thought was an earthquake and ran to the nearest Forsworn camp and saw a bunch of rocks on the ground and them shooting the [censored] outta the Companions.