The formation of Santa María occurred approximately 30,000 years BP, constructing the present cone to a volume of 20 km3 (4.8 cu mi).

Santa María began discharging steam in the afternoon, before rumbling noises were heard within its vicinity at 17:00.

As the evening progressed, a white sand-like substance began showering and blanketing the area, discoloring the landscape with its whitish color.

[3] Large lithics began to rain down the volcano's southern flanks at 01:00 of 25 October, signifying that the eruption had entered its plinian stage.

The eruption continued to shake windows in Cobán until mid-day and its residents detected a sulfrous smell.

The captain of the S.S. Newport used her sextant to measure the height of the eruption column and placed his estimation at 27–29 km (17–18 mi).

A section of the volcano's flank was destroyed, exposing steep cliffs and revealing layers of lava flows and ash deposits extending 1,200 m (3,900 ft) high.

Large pieces of rocks were observed falling and accumulating at the bottom of the scarp in a 150 m (490 ft) debris cone.

[6] Portions of coffee plantations in Xolhuitz, Costa Cuca, Chuva, Progreso and Tumbador were devastated and unrestored.

The stench of animal corpses rotting beneath volcanic debris was intense according to Gustav Eisen who reported the forest conditions in 1903.

Cattle also died in large numbers; some perished during the eruption or in the subsequent days from consuming ash-contaminated water and grass.

Insects were among the fauna that recovered quicker; Eisen found butterflies, beetles, mosquitoes and flies in abundance.

[9] In Suiza, a building heavily occupied by those escaping the eruption collapsed under the accumulated ash, killing 18.

The 26 October issue of Diario de Centro América was heavily focused on the festival while it made no mention of the eruption.

There were no official actions in attempting to calculate the number of fatalities and aid only reached the affected departments in December.

[7] While the eruption continued, the regional authorities of Quetzaltenango became responsible for handling the crisis, as attention of the national government was focused on Fiestas Minervalias.

Furthermore, the official government informed Quetzaltenango authorities that no funds were available for recovery, as were absorbed by the response missions following the April earthquake.

[10] Quetzaltenango regional authorities announced that the West zone agricultural harvest was destroyed, and forecasted a famine due to food shortages.

[11] On top of food shortages, the lack of water and power supply due to ash added to the turmoil of residents.

In late November, Quetzaltenango officials allocated 15,000 pesos for cleaning works another 5,000 to repair its aqueducts.