Mexico is a country defined by a dynamic and complex geological setting. The nation is situated where several major tectonic plates converge, resulting in frequent seismic activity and a high concentration of volcanic structures. This intense interaction has created a vast and diverse volcanic topography, ranging from small cinder cones to towering stratovolcanoes. Understanding the true number of volcanoes requires considering the scientific criteria used to classify these mountains.
Defining the Volcanic Landscape: The Official Count and Classification
The precise number of volcanoes in Mexico is not static, depending heavily on how they are defined and classified. Geologists categorize structures as active, dormant, or extinct. An active volcano has typically erupted within the last 10,000 years, meaning a future eruption is possible. An extinct volcano is not expected to erupt again, often because its magma supply has been cut off.
The Global Volcanism Program, which tracks volcanoes active within the last 10,000 years, lists 35 Holocene volcanoes for Mexico. However, national monitoring agencies use a broader count that includes all potentially active centers. The Mexican National Center for Disaster Prevention (CENAPRED) recognizes at least 46 to 48 active or potentially active volcanic centers. This figure includes major composite volcanoes and extensive monogenetic volcanic fields, which contain hundreds of smaller, short-lived vents but are counted as a single active center.
The Trans-Mexican Volcanic Belt: Geological Context
Mexico hosts a large number of volcanoes due to the presence of the Trans-Mexican Volcanic Belt (TMVB). This vast geological feature runs nearly 1,000 kilometers across central-southern Mexico, from the Pacific Ocean to the Gulf of Mexico. Unusually for a subduction-related chain, the TMVB is not parallel to the coastline and encompasses approximately 160,000 square kilometers.
The TMVB results from the complex interaction of the North American, Cocos, and Rivera tectonic plates. The oceanic Cocos and Rivera plates are forced beneath the continental North American plate in a process called subduction, occurring along the Middle American Trench. As the oceanic plate descends, heat and pressure release fluids into the overlying mantle wedge. These fluids lower the melting point of the mantle rock, generating magma that rises through the crust, forming the volcanic belt.
The oblique angle of subduction caused the TMVB’s unusual east-west orientation. The belt is characterized by diverse structures, including towering stratovolcanoes, calderas, and extensive fields of small cinder cones.
Mexico’s Highest-Risk Active Volcanoes
While the TMVB contains dozens of volcanic centers, a few stand out due to their high activity levels and their proximity to densely populated areas. The three most significant high-risk volcanoes are Popocatépetl, Volcán de Colima, and Pico de Orizaba. These volcanoes are monitored by CENAPRED, the national authority responsible for tracking volcanic hazards.
Popocatépetl
Popocatépetl, meaning “smoking mountain,” is the most hazardous volcano in Mexico. It is located only about 70 kilometers southeast of Mexico City, and an estimated 25 million people reside within a 100-kilometer radius of its crater. Since 1994, the volcano has been in a period of heightened activity. This activity is characterized by frequent gas-and-ash emissions, steam plumes, and periodic minor explosions, necessitating a permanent, high-level monitoring system.
Volcán de Colima
In the western part of the TMVB, the Volcán de Colima, often referred to as the Fuego (Fire) Volcano, is the most consistently active in the country. It has a history of around 50 significant eruptions over the last 430 years. Its frequent dome growth and collapse cycles produce dangerous pyroclastic density currents, which pose a direct threat to nearby towns and villages. The most recent documented activity occurred in 2019.
Pico de Orizaba
The third high-risk volcano is Pico de Orizaba, or Citlaltépetl, which is the highest mountain in Mexico. Although its last major eruption was in 1846, it is still considered potentially active due to its immense size and the large population at its base. The volcano currently exhibits small active fumaroles near its summit crater. Its steep slopes present a risk of lahars, or destructive mudflows, during the rainy season.