This event comes with major uncertainties. There is only limited record. In Wiegel and ASCE (1980), an eye witness report from Northern Luzon is provided: "... trees were overthrown by the terrific force of the waves of the sea, which invaded the land for a distance of a league, and in that area the land could not be seen".

This description highlights a major tsunami event inundating a large area. The NGDC database lists 5 more reports on this event describing major structural damage and destruction to several settlements (including several monestaries.

There are repeated reports of subsided mountains and hills.

Considering the effects described for the provinces of Illocos Norte and Cagayan, a new epicenter was proposed North of both provinces along the Luzon Trench. There is some chance, that the tsunami was caused by a landslide.