In the interest of narrowing questions down, I am splitting these out into particular elements and element combinations.
So, in summary, Ley Lines have just become active again on Modern Earth, and are wreaking natural and unnatural havoc on the world.
This question will focus on the two remaining types of ley lines: Earth and Air, and their interactions with the world around them, as well as interaction between them. Ley lines are not restricted to a particular area, but exist across the entire world. Some places have denser concentrations than others. (Interactions with Fire are covered here, Water is covered here, and Wood is here).
What are catastrophes that could be caused by very high volumes of Earth and Air magic going rampant, and clashing with other elemental magics also going rampant? Again, this can be of any scope, as long as it does not result in a mass extinction event. And I'm quite okay with every combo not always producing the same results.