noun
precursor phenomenon; premonitory sign; advance warning
Refers to observable events or signs that precede and indicate a larger event, often used in scientific, technical, or formal contexts such as earthquake prediction or disaster warnings.
地震の前兆現象として、井戸の水位が変化することがある。
As a precursor phenomenon of earthquakes, the water level in wells sometimes changes.
このデータは火山噴火の前兆現象を示している。
This data indicates precursor phenomena of a volcanic eruption.