is one of the most eruptive places on Earth
is a geological feast for the eyes.
For a country only as big as Ohio, this North Atlantic island boasts
a remarkable diversity of topography, including rugged mountain ranges,
massive glaciers, stark alpine deserts, waterfalls, plateaus, and
port city of Vestmannaeyjar, as a fissure on the island erupts
in the background, 1973.
Perhaps the most striking
geological feature of Iceland is its volcanoes. Pocked by more than
two hundred volcanoes, Iceland is one of the world's most volcanically
active regions, spewing a third of the earth's total lava flow over
the past five hundred years (our geological map
tells you about some of the most active areas).
Sitting Smack Dab
on a Mid-Ocean Ridge
Icelanders can thank
their island's unique location for this intense volcanic activity.
Slicing through the center of modern-day Iceland is a geological
feature called a mid-ocean ridge. This is the boundary between two
continental plates, which are the enormous slabs that make up the
earth's crust. As these plates slowly move apart -- at a rate of
about an inch each year -- fissures periodically form in the crust.
Over time, these gaps allow molten rock from underground to surface
as lava, creating Iceland's many volcanoes.
There are many places
on earth where two continental plates drift apart, but most of these
sites are deep under water. Iceland is one of the few places in
the world where such a boundary occurs above sea level, helping
to explain the island's unusually active geology.
Not only is the mid-ocean
ridge responsible for building the volcanoes on Iceland, it's also
the driving force behind the creation of the entire island. Beginning
about seventy million years ago -- long after the earth's other
continents had formed -- lava from volcanic eruptions along the
mid-ocean ridge cooled as basalt (a dark rock) to make all of Iceland's
present-day land surface.
These ancient lava flows
helped to shape the island's plateaus, mountains, and other topographical
features. Today, in fact, a historical record of lava flows is visible
in the parallel layers of basalt that line the sides of many of
Iceland's glacier-cut valleys.
An Explosive History
second day of Grimsvotn's 1998 eruption from under the Vatnajokull
Photo: Freysteinn Sigmundsson
Documented history of
Iceland's volcanic eruptions began in 874 A.D., when the Vikings
first settled the island. Since that time, the island has had about
125 volcanic eruptions -- more than any other comparably sized region
in the world. Some of these eruptions have led to famine, destroyed
homes, and generally wreaked other havoc on human settlements.
Most notably, Iceland
is the site of the largest lava flow in recorded global history.
In 1783, an eruption at a mountain called Laki tore a chain of giant
craters in the earth. Besides releasing 2.9 cubic miles of lava
and inundating 218 square miles of land, the craters also belched
a haze of toxic particles into the air, which was reported as far
away as Syria. The poisoned air devastated Iceland's livestock and
farmland, contributing to a famine that killed about a quarter of
the island's residents.
About two hundred years
later, in 1973, another destructive eruption occurred on the small
island of Heimaey, several miles from mainland Iceland. The event,
which lasted several months, destroyed about a third of the town
of Vestmannaeyjar, the nation's premier fishing center. Authorities
had to evacuate most of the town's residents, and spray seawater
on the lava flows to halt their advance into the town.
A Volcanic Asset
island of Surtsey being created in a 1963 eruption. Surtsey
is now one of the most geologically-studied features in the
Many Icelandic eruptions
have offered important scientific insights. Between 1963 and 1967,
for instance, an underwater volcano twenty miles south of Iceland
belched enough lava to form a new island, which Iceland named Surtsey.
Since it's rare for volcanoes to make permanent new islands, Surtsey
has offered an important opportunity for scientists to investigate
this geological process. Surtsey has also been an invaluable laboratory
for biologists to monitor the arrival of colonizing species to a
barren new island.
Averaging one eruption
about every five years, Iceland certainly has an intimidating --
and sometimes destructive -- geology. But this geology is, arguably,
more of an asset than a hazard. Volcanoes have sculpted Iceland's
unique and beautiful landscape, which Icelanders and tourists alike
savor. Many come to the island to see volcanic hot springs and geysers,
and possibly even witness a fiery red river of lava from an erupting
If you're planning a
vacation in Iceland, you can bask in the island's geothermal pools
and enjoy the scenery without fear. Because the island is so sparsely
populated, the overall threat volcanoes pose to people is low: The
majority of blasts have occurred far from human settlements.
If you're a scientist,
you can also find plenty of fascinating attractions. Researchers
from around the world come to Iceland to study everything from ancient
lava flows to the movement of continental plates. In fact, Iceland
is a gift to science, offering glimpses of land-based geological
processes not visible anywhere else on earth.
to know more about Iceland's volcanoes? Here's a few links:
the 1998 Grimsvotn eruption
from the University of Iceland
Man Against Volcano
an account of the devastating 1973 eruption on Haimaey. A 33-page
printable PDF file.
for volcanology in Iceland, hosting an international team of scientists