1May, 980 18, that is, 13 hours after this photo was taken, the volcano erupted, eventually killing 57 people including these volcanologists.
Formation principle
The temperature and density inside the earth are not uniform, and mantle convection or mantle plume is formed inside the mantle. When high-temperature substances rise to the shallow layer of the earth, partial melting occurs due to the decrease of pressure. Under the action of external force, these molten substances converge in the shallow layer of the earth to form magma sacs.
When the pressure of magma sac is greater than that of stratum, magma will break through the crust along faults or weak points, leading to volcanic eruption.
Another kind of volcano is caused by plate interaction, for example, in the subduction zone or collision zone of plates, local high temperature is formed due to friction, and the dehydration of some water-bearing minerals also reduces the melting point of rocks, which will also form magma sacs, thus triggering volcanic activity.