The scale typically used by most seismologists to measure the magnitude of an
earthquake is what

The richter scale is most common in the united states, but the mercalli scale is most common worldwide

Magma forms by partial melting of upper mantle and crust. partial melt means that only a fraction of the available material forms a melt, and that the remainder stays solid. the partial melt rises because of its lower density and ascends through he crust. this is so conclusive mean the answer would be magma igneous rocks or balistic magma.