LR89

I'm learning about earthquakes in one of my classes and am unsure about what type of interactions at plate boundaries can cause them. Can earthquakes occur at a continental-continental convergent plate boundary? Or is mountain formation the only result when the continental plates collide?

Why does laminar flow occur at low velocities and turbulent flow occur at high velocities? I'm trying to understand it in terms of flow over a cylinder and adverse pressure gradients but I can't understand why an object moving at a higher velocity would experience a greater adverse pressure gradient than one moving at a slower velocity. Thank you!