SME
Grade 12 Science · Problem type
Which waves reach a station
Use this for “Which seismic waves reach a station 120° from an earthquake, and why do no S waves arrive past 104°?”
Explore
A station 60° away gets both P and S waves, straight through the mantle.
P waves arrive first because they are faster.
Assumptions
•
P waves travel through solids and liquids; S waves travel only through solids.
•
The outer core, 2,890 km down, is liquid, and waves bend where they cross into it.
•
Angles are measured round Earth’s center from the earthquake’s epicenter.
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Related lessons
Earthquakes, seismic waves and Earth's interior
Main lesson
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Seafloor spreading from magnetic stripes
Use this for “Rock 100 km from the ridge is 4 million years old. How fast is the seafloor spreading?”
P, S or surface wave?
Use this for “Which seismic wave cannot travel through the liquid outer core?”
Earth’s heat or the Sun’s?
Use this for “Which of these is powered by Earth’s internal heat, like hot springs?”