How big is the Pacific Ring of Fire?
The Ring
of Fire dominates the Pacific Ocean. It's a string of at least 450
active and dormant volcanoes that form a semi-circle, or horse shoe,
around the Philippine Sea plate, the Pacific Plate, Juan de Fuca and
Cocos plates, and the Nazca Plate. There is a lot of seismic activity in
the area.
About 90 percent of all earthquakes strike within the
Ring of Fire. This means people's lives are under almost constant threat
in Indonesia, the Philippines, Malaysia, Japan, Australia and New
Zealand, Papua New Guinea, and other island nations like the Solomon
Islands, Fiji, and many more in Melanesia, Micronesia and Polynesia, all
the way east to the western seaboard of the North and South Americas.
Although levels of threat differ depending on local factors like your
proximity to the quake's epicenter, whether it's out to sea or on land -
and standards of housing.
Why so many volcanoes in the Ring of Fire?
The
tectonic plates move non-stop over a layer of partly solid and partly
molten rock. This is called the Earth's mantle. When the plates collide
or move apart, for instance, the Earth moves, literally. Mountains, like
the Andes in South America and the Rockies in North America, as well as
volcanoes have formed through the collision of tectonic plates.
Many
volcanoes in the Ring of Fire were created through a process of
subduction. And most of the planet's subduction zones happen to be
located in the Ring of Fire.
What is subduction?
Subduction happens when
tectonic plates shift, and one plate is shoved under another. This
movement of the ocean floor produces a "mineral transmutation," which
leads to the melting and solidification of magma - that is, the
formation of volcanoes. Basically, when a "downgoing" oceanic plate is
shoved into a hotter mantle plate, it heats up, volatile elements mix,
and this produces the magma. The magma then rises up through the
overlying plate and spurts out at the surface.
If, however, the overlying plate is ocean, it can produce a chain of
volcanic islands like the Marianas. This is also where we see the
Earth's deepest trenches and deepest Earthquakes.
When and where were the worst earthquakes in the Ring of Fire?
The
worst earthquake in the Ring of Fire - and, with it, the world - struck
Chile on May 22, 1960. It was a 9.5-magnitude quake. That's according
to the US Geological Survey's list of the "Largest Earthquakes in the
World Since 1900."
It's closely followed by the Great Alaska
Earthquake of 1964 (magnitude 9.2), the Northern Sumatra earthquake -
also known as the Indian Ocean Tsunami - on December 26, 2004 (magnitude
9.1), and one off the East Coast of Honshu, Japan, on March 11, 2011
(magnitude 9.0), which led to a tsunami and ultimately the nuclear
disaster at Fukushima.
