Buddha sitting in Bhumisparsha-mudra posture (calling the earth to be his witness).
Bhumisparsha means 'touching the earth'. It is more commonly known as the 'earth witness' mudra. This mudra, formed with all five fingers of the right hand extended to touch the ground, symbolizes the Buddha's enlightenment under the bodhi tree, when he summoned the earth goddess, Sthavara, to bear witness to his attainment of enlightenment.