What caused this damage to the train tracks?

I wonder what would cause damage like this?

Who felt the Earth Quake?  I missed it completely!  When living in California I felt a lot of them.  Before they would happen the animals in the neighborhood would go crazy including my dog.  My dogs gave me no warning today.  I wonder... do they always give warning?  I wonder does it have to be a certain magnitude?  I wonder........

To keep up with Earth Quakes in Oklahoma -
http://earthquaketrack.com/p/united-states/oklahoma/recent

I wonder what causes an Earth Quake?  I wonder I wonder I Wonder.