The correct answer is - transform.
The southwestern part of the United States is under the influence of a transform plate boundary. The small plate on which this part of the country lies is moving parallel to the much bigger North American continental plate.
With this movement, the plates move parallel to one another, creating a horizontal movement because of the horizontal pressure. Because of the movement, there's lot of adjustments happening deep into the crust, thus creating lot of earthquakes, as well as faults. Both the earthquakes and the faults are contributing to the damage on the infrastructure, most noticeably on the roads.
