Santa María Volcano
Santa María Volcano is an active stratovolcano that is located in Guatemala and is part of the Sierra Madre, a string of volcanoes that stretches across the western side of Guatemala.
The volcanoes in this string were formed by subduction activity, when the Cocos Plate moved under the Caribbean Plate. An eruption in 1902 produced a crater that now holds a lava dome known as Santiaguito, which was created during another eruption in 1922. These domes hold active vents and in 1929, part of the Santiaguito dome collapsed, producing pyroclastic flows that killed up to five thousand people. Typically, these types of domes do not produce violent eruptions, with most activity consisting of ash plumes and small pyroclastic flows.
It is thought that Santa María Volcano began its active phase around 30,000 years ago. During its early years, the volcano produced many small eruptions that built up its first cone. This changed suddenly, when the volcano displayed long periods of dormancy and stronger eruptions between those periods. The first historically recorded eruption occurred in 1902, after a dormancy period of at least five hundred years. This eruption was one of the largest in the twentieth century and was labeled as “Colossal.” Ash from the eruption was found as far away as California and was not detectable due to a lack of previous eruptions.
Today, much of the activity that is produced from Santa María Volcano originates from Santiaguito. The largest threats from the volcano come in the form of lahars, which form during the rainy season, moving loose debris from the slopes to the areas below and around it. These mudslides often affect roadways and river systems. Lava flow is not a major concern to cities near the volcano, as it moves slowly down its slopes, but faster and more dangerous lava flows can occur. If the entire volcano were to collapse, an area of thirty-nine square miles could be affected, but this danger is not thought to pose an immediate threat.
Image Caption: Santiaguito volcano, seen from the summit of Santamaria. Credit: Worldtraveller/Wikipedia (CC BY-SA 3.0)