Many of the gigantic volcanoes are conical in shape (e.g., Mount Fuji), while others form steep lava domes (e.g., Mounts Dai and Unzen).
Gigantic volcanoes can form more easily on Mars, because unlike Earth, whose crust is made up of many separate plates constantly in flux, the Red Planet has a thick, rigid outer shell made of a single plate.
It's about 4 o'clock on a Thursday, and a caftan-bedecked Karlie Kloss is perched on the edge of a gigantic, fuming volcano crater, her bare legs and feet dangling into the hazy void.
Aso, Kyushu, Japan 5,223 1,592 864 The gigantic caldera of this volcano is occupied by many peaks, including Naka-dake, one of Japan's most active volcanoes.
Although there are no known active volcanoes, the gigantic Mons Olympus was active until 100,000 years ago - very recent in geological terms.
Even scarier are the mega-tsunamis formed by gigantic landslides at ocean island volcanoes.
Anyone in Seattle, Washington, who looks southeast on a clear day, will catch sight of the gigantic, looming Mount Rainier, a dormant glacier-covered volcano.
But too much volcanic activity can also be bad: Jupiter's moon Io is jostled so much by the gravitational pull, or tidal force, of its gigantic parent and neighboring moons that its volcanoes erupt almost continuously--enough to coat the moon's surface with fresh lava about every million years.
Katmai, Alaska, U.S. 6,716 2,047 1912 The summit of this volcano collapsed in 1912 following the gigantic explosion of nearby Novarupta Volcano--the largest eruption recorded in the 20th century.
