Mostly its the tectonic plates that shift under us that causes earthquakes, how they shift changes the damage the earthquake can cause so tectonic plates unless u want the mythological one which is some earth god scratching his back
Ultramafic,as components of mafic rocks like olivine and pyroxene solidified at very high temperatures, so mafic minerals will decompose as the result of chemical weathering more rapidly than felsic minerals
Small antennas on the spacecraft can beam weak radio signals back to earth meaning it can in some way communicate
