One page per term. Look up any term you encounter in a block, an assessment, or a partner conversation. If a term you're looking for isn't here yet, it's listed as "Coming soon" below: ask Ms. Jayanthi/Mr. Ignash and we'll prioritize it.
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Liquefaction
When saturated soil temporarily behaves like a liquid under shaking. Why soft-ground cities lose buildings even when the buildings themselves don't fail.
Word bank: Lovelock (1965)
The 30 words you meet in the Unit 0 Block 2 paper, each tagged with where it comes from and whether it sits in the paragraphs that carry the argument. Plain-English definitions plus translations in six languages.
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Subduction
When one tectonic plate dives beneath another. The setup for the largest earthquakes and tsunamis on Earth.
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Megathrust
The biggest kind of earthquake: a sudden slip on the interface between subducting plates. M9+.
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Pyroclastic flow
A fast-moving cloud of superheated gas and rock from a volcanic eruption. No engineering defense: only distance and warning save lives.
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Lahar
A volcanic mudflow: ash + water moving like wet concrete down valleys. Can destroy villages years after the eruption.
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Magnitude vs. intensity
Two different things people confuse: how much energy the quake released (magnitude) vs. how strongly the ground shook somewhere (intensity).
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Volcanic Explosivity Index (VEI)
The 0–8 logarithmic scale for ranking eruption size. Pinatubo 1991 was VEI 6.
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Lithosphere / asthenosphere
The rigid outer shell of Earth that's broken into plates (lithosphere) and the slowly-flowing layer beneath (asthenosphere) that they move on.
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Transform fault
Where two plates slide horizontally past each other. Big shaking, no tsunami. Examples: San Andreas, Anatolian.
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Hotspot
A plume of mantle material that punches through a plate from below: Hawaii's source. Mostly produces effusive shield volcanoes, not catastrophic eruptions.