For water, an earthquake (actor -um-, umi- & inst) to cause a section of a mountain, bank, cliff face, stone wall (theme i-) to slide, as described above.
gumday; umegday; egday; magday
Actor is often a third person pronoun -na, presumably signalling an unknown referent.
Ihamadyun muntapeng ti ag'aga ya enegdayna.
Construct the stone wall carefully because (otherwise) it will cause it to quickly slide.
Also common is a passive form without an actor.
Damūna han negday ad ugga hi payaw Langngeh.
That which was caused to slide yesterday in Langngeh's pond field is wide.
mi-: megday; -um-: gumday; umi-: umegday; i-: egday