Un estratovolcán es un tipo de volcán cónico y de gran altura, compuesto por múltiples capas de lava endurecida, piroclastos alternantes (surgidos por una alternancia de épocas de actividad explosiva y de corrientes de lava fluida) y cenizas volcánicas. Estos volcanes están caracterizados por un perfil escarpado y erupciones periódicas y explosivas. La lava que fluye desde su interior es altamente viscosa y se enfría y endurece antes de que pueda llegar lejos. La fuente de magma de estas montañas está clasificada como ácida o alta en sílice, con presencia de riolita, dacita y andesita. Muchos estratovolcanes exceden los 2500 metros de altitud. Aunque a veces se denominan ‘volcanes compuestos’, los vulcanólogos prefieren utilizar el término «estratovolcán» para establecer una distinción, debido a que todos los volcanes, sean del tamaño que sean, presentan una estructura (de capas) compuesta, esto es, se desarrollan sobre los materiales de sucesivas erupciones.

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A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic explosive eruptions and effusive eruptions, although some have collapsed craters called calderas. The lava flowing from stratovolcanoes typically cools and hardens before spreading far due to high viscosity. The magma forming this lava is often felsic, having high-to-intermediate levels of silica (as in rhyolite, dacite, or andesite), with lesser amounts of less-viscous mafic magma. Extensive felsic lava flows are uncommon, but have travelled as far as 15 km (9.3 mi). Stratovolcanoes are sometimes called "composite volcanoes" because of their composite layered structure built up from sequential outpourings of eruptive materials. They are among the most common types of volcanoes, in contrast to the less common shield volcanoes. Two famous stratovolcanoes are Krakatoa, best known for its catastrophic eruption in 1883 and Vesuvius, famous for its destruction of the towns Pompeii and Herculaneum in 79 CE. Both eruptions claimed thousands of lives. In modern times, Mount Saint Helens and Mount Pinatubo have erupted catastrophically. Existence of stratovolcanoes has not been proved on other terrestrial bodies of the solar system with one exception. Their existence was suggested for some isolated massifs on Mars, e.g., Zephyria Tholus.

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