It's Raining Fish and Spiders (33 page)

Upon receipt of tsunami watches and warnings, coastal National Weather Service (NWS) offices activate the Emergency Alert System (EAS) via NOAA Weather Radio. All broadcasters (TV, AM/FM radio, and cable TV) receive the tsunami EAS message, as well as anyone who has a weather radio receiver (this includes healthcare facilities, schools, businesses, and homes). NOAA Weather Radio also activates the All-Hazard Alert Broadcast (AHAB) units located in remote coastal areas, alerting people in isolated locations.

Where Do the Watches and Warnings Come From?

Two tsunami warning centers look for earthquakes and any indications that a tsunami might have been generated. If they pick up evidence of a tsunami, they issue watches and warnings for their assigned areas.

The West Coast/Alaska Tsunami Warning Center in Palmer, Alaska, covers California, Oregon, Washingon, Alaska, and British Columbia.

The Pacific Tsunami Warning Center in Ewa Beach, Hawaii, covers the Aloha State as well as all other American territories in the Pacific. It also serves as the International Tsunami Warning Center for twenty-five other member countries in the Pacific Ocean Basin.

If you live on the coast, make an evacuation plan, keep it updated, and be ready to use it. There's nothing you can do to stop a tsunami, but you can be ready with the right response when “Tommy Tsunami” pays you a visit!

I Dunno Where I'm Gonna Go When the Volcano Blows!

When I think of a volcano, the first image that comes to mind is a large, tall mountain with orange fire and lava spewing out of the top. Ka-boom! Volcanoes
can
explode violently, destroying everything within a few miles of the eruption in a matter of minutes. But there are many volcanoes where the lava seeps out so slowly that you can actually safely walk around them! The severity of a volcano's eruption depends on the thickness and composition of its magma.

Mount St. Helens volcano, Washington
U.S. Geological Survey/Department of the Interior

A volcano is an opening, vent, or rupture in the surface of the planet that allows material from inside the Earth to escape. When watching an erupting volcano, many of us may feel the same emotions as people in ancient times who believed volcanoes were supernatural beings. We stand in awe of this force of nature and are unnerved that what was once a peaceful mountain with pretty snow on top, has been transformed into a raging beast throwing a horrendous, molten magma, fire-spewing fit!

U.S. Geological Survey/Department of the Interior

That was the case when Mount St. Helens in the state of Washington erupted in 1980; it had not erupted for 123 years. Most people thought Mount St. Helens was a beautiful, peaceful mountain, not a dangerous volcano.

Volcanoes are generally found where tectonic plates meet violently—where they are pulled apart or jammed together. Volcanoes are rarely found where two tectonic plates slide past each other.

Worldwide, there are 1,500 active—that's right,
active—
volcanoes. Six hundred of those are on the land and the rest are on the ocean floor. All the volcanoes of the world, active, dormant, or extinct, are important because volcanoes make up 80 percent of the Earth's surface.

Hot Magma, Baby!

When magma seeps or blasts onto the Earth's surface, it's called
lava
. How explosive an eruption is depends on how runny or sticky the magma is. If magma is thin and runny, gases easily escape from it. When this type of magma erupts, it flows out of the volcano. Magma that's thick and sticky doesn't flow easily and blocks the gases from escaping. Pressure builds up until the gases escape violently and explode. In this type of eruption, the magma blasts into the air and breaks apart into pieces called
tephra.
Tephra can range in size from tiny particles of ash to house-size boulders!

Explosive volcanic eruptions can be dangerous and deadly. Clouds of hot tephra can blast out from the side or top of a volcano. When Mount St. Helens erupted, the top blew clean off the mountain and fiery clouds raced down the mountainside, destroying everything in their path.

Volcanic ash falls back to Earth as if it were powdery snow, but of course it doesn't melt. If the ashfall is thick enough, it can suffocate plants, animals, and humans. When hot volcanic materials mix with water from streams or melted snow and ice, mudflows are formed. Mudflows can be as dangerous as lava flows. They have buried entire communities near erupting volcanoes.

Where Do These Bad Boys Come From?

Like earthquakes, volcanoes exist because of the rigid plates in the Earth's crust. There are sixteen major plates that float on a softer layer of rock in the Earth's mantle. Most volcanoes occur near the edges of plates.

Sometimes when plates push together, one plate slides beneath the other. This is called a
subduction zone
. When the plunging plates get deep enough inside the mantle, some of the rock on the overlying plate melts and forms magma that can move upward and erupt at the Earth's surface.

At rift zones, where plates are moving apart, magma can reach the surface and erupt. Some volcanoes occur in the middle of plates at areas called
hot spots
—places where magma melts through the plate.

These Guys Must Be on Steroids!

Repeated eruptions cause volcanoes to grow. There are three main shapes of volcanoes based on the stuff that comes out of them when they erupt.

Stratovolcanoes
are built from eruptions of lava and tephra that pile up in layers like cake and frosting. They form volcanoes with symmetrical cones and steep sides.

Cinder cone volcanoes
are created by erupting lava that breaks into small pieces as it blasts into the air. As the lava pieces fall back to the ground, they cool and harden into cinders that pile up around the volcano's vent. Cinder cones are very small, cone-shape volcanoes.

Shield volcanoes
are formed by eruptions of flowing lava. The lava spreads out and builds up volcanoes with broad, gently sloping sides. The shape resembles a warrior's shield.

Here Are a Few of the Most Famous Volcanic Faces!

Nasty, Gnarly, and Naughty Pacific Northwest Winds!

In the hurricane section, I mentioned the book that I think is probably the best weather novel ever written (besides
Category
7 by Bill Evans and Marianna Jameson!):
Storm
by George R. Stewart. Stewart, a professor of English at the University of California, Berkeley, wrote about a nasty storm referred to as “Maria.” While “Maria” was a nasty fictional storm, some nasty, gnarly,
real
storms frequently strike the northwestern Pacific Coast of the United States.

Residents in that area of the country never experience a hurricane or a tornado, but they are battered by giant storms called
extra-tropical lows
that rival any hurricane. An extra-tropical low is basically your everyday low-pressure system, except it grows to be extremely large and dangerous. It's a low-pressure system on steroids!