This is a common phenomenon that can happen anyplace in Skyrim. If you Google 'earthquake Skyrim' you will find numerous threads about it on the internet. As far as I'm able to tell, the cause of these mysterious earthquakes remains unknown.
I only get earthquakes from one specific spot though. Near the one dwarven ruin that starts the atherium quest. I don't recall getting them anywhere else.
However I'm thinking this was a random event. I did a little more digging and noticed there's a spawn location just on the opposite side of the hot springs in that third screenshot. So something spawned there. Now I just gotta figure out what it was.
What level are you? If you are high enough, some dragons have shout attacks. Also dragon landing has earthquake effect. Maybe a dragon was fighting a giant or a bear or a pack of wolves. The dragon at Bonestrewn Crest likes to fly around west of there and likes to fight other locals.
Level 25 to 27, but there is currently no dragon there. I killed it about three in-game days ago. It also wouldn't explain the ghostly remains I found.
The earthquakes near Arkngthamz are normal. It's all part of what's happening inside.
Is your character Arch-mage? There's a recurring quest - Aftershock - with Magical Anomalies spawning almost anywhere. Throw in a wandering dragon, and even after you kill the one at Bonestrewn Crest, it gets visitors, and you could find the dragon did the work for you.