Topic, surrounding volcanoes! And the entire West Coast of our nation resides on the
Pacific Rim so we actually have a real stake in what happens when a volcano erupts, etc.
Below are links that you should check out from the USGS showing the earthquakes that
happened just in one day around the world. Evidently one happened in Oklahoma.
I also want to alert your to the amazing tools that you can manipulate at Google Earth.
Fantastic Google Earth Links at the USGS to explore:
From the readings above for this week:
Like earthquakes, volcanoes are clustered along boundaries between tectonic plates,
as Figure 3-5 shows. Movement within Earth and between the plates
generates magma (molten rock). Being less dense than the surrounding rock, magma
migrates toward the surface. Some reaches the surface and erupts, and is then called lava.
A volcano is the surface vent where lava emerges. The magma may flow over the
surface, forming a plain of volcanic rock, or it may build up to form a mountain. The
chemistry of the magma/lava determines its texture and therefore the type of landform it
builds. The chemistry of magma/lava also determines whether the eruption is violent or
Figure 3-5 Earth's tectonic plates.
(a) The major plates of Earth's crust move relative to one another, generally at rates of a
few centimeters per year. (b) These motions cause earthquakes that are concentrated
along plate boundaries. Ridges with rift valleys at their centers are formed where plates
are moving away from each other, generally in ocean areas. Mountain ranges are created
where plates converge, sometimes with deep-ocean trenches on the seaward side of the
Shield volcanoes erupt runny lava that cools to form a rock called basalt. They are
called shield volcanoes because of their shape (Figure 3-7). Each of the Hawaiian Islands
is a large shield volcano, although the only currently active ones are Mauna Loa and
Kilauea, on the island of Hawaii (the "Big Island"). These generally sedate volcanoes
make news on the rare occasions when they grow more active, and flows of lava threaten
settlements. The mid-ocean ridges are formed of similar basaltic lava.
Class, why is the Pacific Rim called the Pacific Rim?
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