Question

What causes earthquakes?

exposed magma at a divergent boundary

trapped magma at convergent boundaries

friction at transform plate boundaries

buckling rocks at a convergent boundary

Answer 1

Short answer: The main causes on your list are friction at transform plate boundaries and buckling (compression and faulting) at convergent boundaries.

More detail on each option:
- exposed magma at a divergent boundary — not typically a primary cause of tectonic earthquakes. Magma movement or diking at spreading ridges can produce earthquakes (volcanic/tectonic events), but “exposed magma” itself isn’t the usual mechanism.
- trapped magma at convergent boundaries — magma movement or pressure changes can trigger volcanic earthquakes, but most large earthquakes at convergent zones are from fault slip (subduction-related thrusting), not from “trapped magma.”
- friction at transform plate boundaries — yes. Plates sliding past one another lock and then suddenly slip, releasing energy as earthquakes (classic example: San Andreas Fault).
- buckling rocks at a convergent boundary — yes. Compression causes folding and thrust faulting (rock failure), producing earthquakes (e.g., megathrust earthquakes in subduction zones).

So pick: friction at transform boundaries and buckling rocks at convergent boundaries.