Earthquakes or tremors precede eruptions.
Seismic activity (earthquakes and tremors) always occurs as volcanoes awaken and prepare to erupt and are a very important link to eruptions. Some volcanoes normally have continuing low-level seismic activity, but an increase may signal a greater likelihood of an eruption. The types of earthquakes that occur and where they start and end are also key signs.
Wikipedia, Prediction of volcanic activity, 2018
Earthquakes and tremors always precede volcanic eruptions. However 1400 years ago this was portrayed in the Quran.
[Quran 99.1-2] If the earth is shaken with its quake. If the earth brings out its loads.
Earth brings out its loads by volcanic eruptions. In the Quran earthquakes precede volcanic eruptions.
How could an illiterate man who lived 1400 years ago have known that earthquakes precede volcanic eruptions?