仁王般若經疏 1.71

1.71

是時世界其地六種者，第四神力動地。何故動地？欲動眾生有所得心，令悟無所得般若也。六動者，東涌西沒、西涌東沒、南涌北沒、北涌南沒、邊涌中沒、中涌邊沒。又解：如《地經》說動、涌、震、起、擊、吼為六也。

"At that time, the ground of the world [quaked] in six ways": the fourth supernormal power, shaking the earth. Why did he shake the earth? He wished to shake the mind of grasping (prāptitva) in sentient beings, causing them to awaken to the prajñā of non-grasping (aprāptitva). The "six quakings" are: welling up in the east and sinking in the west; welling up in the west and sinking in the east; welling up in the south and sinking in the north; welling up in the north and sinking in the south; welling up at the edges and sinking in the middle; welling up in the middle and sinking at the edges. Another explanation is: as the Di jing explains, moving, welling, trembling, rising, striking, and roaring constitute the six.