Geoscience Reference
In-Depth Information
Spreading
cloud of
smoke
and ash
Layers of
lava and
pyroclastic
material
Pyroclastic
flow
Ash fall
Magma chamber
(b)
(a)
Figure 13.35 Composite volcanoes.
(a) Composite volcanoes consist of layers of lava and pyroclastic material that pile up around one or more
conduits to subterranean magma chambers. (b) Mount Fuji in Japan, reverently called
Fuji-san
by the Japanese people, is a composite volcano.
shown in Figure 13.11. A well-known tectonic feature associated
with a number of volcanic arcs is the
Pacific Ring of Fire
, which
follows most of the outline of the Pacific plate (Figure 13.36).
Using New Zealand as an arbitrary starting point, the Pacific
Ring of Fire extends northwestward to the eastern coast of Asia,
and north across the Aleutian Islands of Alaska. From there, it
continues south along the western coast of North and South Amer-
ica. This region contains about 75% of the world's volcanoes,
including Mount Ruapehu in New Zealand, Mount Pinatubo in the
Philippines, Mount Fuji in Japan (Figure 13.35b), Kliuchevskoi
Volcano on Russia's Kamchatka Peninsula, Augustine Volcano in
Alaska (Figure 13.33a), Mount Garabaldi in Canada, and Cotapaxi
in Chile, just to name a few. Most of these volcanoes are compos-
ite structures and have formed because subduction is occurring at
many places along the Pacific plate. Given the tectonic stresses that
occur in these areas, the plate boundary is known for earthquakes.
Pacific Ring of Fire
The chain of volcanoes that occurs along
the edge of the Pacific lithospheric plate.
Augustine
volcano
North
American plate
Kliuchevskoi
Eurasian plate
Mt. Garabaldi
Mt. St. Helens
Pacific
Ring of Fire
Mt. Fuji
Mt. Capulin
Mauna Loa
Hawaiian
Hotspot
Mt. Pinatubo
Cotapaxi
Cocos
plate
Indian
plate
Pacific
plate
South
American
plate
Krakatoa
Nazca
plate
Australian
plate
Figure 13.36 The Pacific Ring of
Fire.
Subduction along the Pacific
plate and subsidiary plates (such as
the Nazca and Cocos plates) has
produced many prominent compos-
ite volcanoes. The locations of a few
of them are shown here.
Mt. Ruapehu
Azul
Antarctic
plate
