San Miguel volcano is a stratovolcano that rises to an elevation of 2132 m, having a total relief of approximately 2000 m. Its diameter at the base is approximately 13 km and its summit crater has a diameter close to 1 km . Meyer-Abich (1956) describes several changes in the shape of the crater since Spanish colonization times that are due to eruptions and internal collapses of the crater walls.
Presently the crater is observed to have concentric faults with collapse benches surrounding an internal crater of approximately 0.2 km in diameter. The interior of the crater is not visible, however a strong emanation of steam and gases that sometimes obscures the summit is observed.
When viewed from the west the summit of the volcano presents a very rugged morphology. It is also apparent, from the change in slope, that the summit has suffered collapse or it has been destroyed by a violent eruption. Later eruptions up to the present continue to fill in the old crater. From the image below it can also be observed that most deposition occurs on the southwestern side of the volcano.
