Earth's Interior

Unit 3

What happened to Krakatoa?

• Goal: Observe changing landforms after the 1883 eruption and raise questions about Earth’s systems.
• Watch: Krakatoa – The Great Volcanic Eruption (0:00–3:32) Krakatoa – the Great Volcanic Eruption
• Task: Use a See-Think-Wonder to capture your observations, inferences, and questions.

Krakatoa

Engage — See-Think-Wonder

• See: What did you observe in the images/video of Krakatoa’s islands?
• Think: What do those observations make you think about how the land changed?
• Wonder: What questions do you have (e.g., Where did the missing islands go? Where did new ones come from)?

Tip: Write specific evidence-based observations (dates, shapes, sizes, sequences).

Engage — Share and Synthesize (Domino Discover)

• In table groups, share one idea or question from your See-Think-Wonder.
• As a class: Surface common trends, key inferences, and open questions.
• Focus: Patterns of change (growth, disappearance, reappearance), possible causes, evidence you used.

How do we figure out what’s underneath Earth’s surface?

• Goal: Use real earthquake data and a computational model to detect patterns in wave arrivals.
• Tools:
  • Data Visualization: Global Seismogram Viewer
  • Simulation: Seismic Waves
• Deliverable: A new See-Think-Wonder based on seismic evidence.

Observing Seismic Data (2011 Japan Quake example)

• Open: Global Seismogram Viewer.
• Find: “Near East Coast of Honshu, Japan, Mag 9.1.”
• Observe: Time of wave arrivals vs. global distance to stations.
• Record: Patterns you see (steady trends, abrupt changes), citing specific traces.

Prompt: Note where arrival times change abruptly. What might cause this?

Seismic Waves Simulation (Part 1)

• Open: Seismic Waves (Tohoku setup link).
• Step 1: Turn on “waves shown” and “label waves on.”
• Step 2: Select “shadow zone only,” “surface,” and “cross section.”
• Run: Watch P (primary) vs. S (secondary) waves across Earth’s interior.

Guiding Questions:

• How do P waves travel compared to S waves?
• Where do waves disappear or change speed/shape?
• What does that suggest about interior layers?

Seismic Waves Simulation (Part 1, continued)

• Switch “waves shown” to “standard waves.”
• Focus: Leading edge of the P wave.
• Observe: How many times do parts of the P wave reflect/bounce? Where and why?

Record: Diagram the motion over time and annotate reflections/refractions.

Density Column

Explore 1 — See-Think-Wonder (Seismic + Density)

• See: Patterns in wave arrivals and in density layering.
• Think: What do these patterns imply about Earth’s structure?
• Wonder: What open questions could be answered next (e.g., composition, phases)?

Tip: Tie seismic evidence (P vs. S behavior, reflections) to density-based layering.

Explain 1 — What do differences in seismic waves tell us?

• Goal: Build a model of Earth’s interior using evidence about how energy drives motion of matter in P and S waves.
• Focus:
  • P waves: Longitudinal; travel through solids and liquids; change speed/reflect with layers.
  • S waves: Transverse; travel only through solids; disappear near the core.

Explain 1 — Modeling P and S Waves (Human Model)

• Observe a human-model demo (or video) of P and S wave motion. Demonstrating P and S waves
• Record in See-Think-Wonder:
  • See: How molecules move in each wave type.
  • Think: Why P moves through liquids/solids but S only through solids.
  • Wonder: What this implies about Earth’s layers.

Prompt: Connect “movement of matter” to “energy from the earthquake.”

Explain 1 — Density & Gravity (from Explore)

• Key idea: Denser materials have more mass in the same space; gravity pulls them toward Earth’s center.
• Implication: Earth’s interior layered by density (heavy metals deeper; lighter silicate rocks near surface).
• Bridge: Seismic patterns + density evidence → infer phase and composition of layers.

Explain 1 — Build Your Model of Earth’s Interior

• Model requirements:
  • At least 3 layers: solid crust, solid mantle, liquid outer core (inner core phase not determined yet).
  • Show where P and S waves do/do not propagate.
  • Indicate relative densities (denser deeper).
• Evidence labels:
  • Seismogram arrival times (abrupt changes)
  • P vs. S behavior (S shadow; P reflections)
  • Density column analogy

Deliverable: Diagram + brief written explanation tying evidence to each model feature.

Explain 1 — Class Consensus Discussion

• Steps:
  1. Selected groups present models.
  2. Peers restate; ask clarifying questions.
  3. Table confers; then whole-class agree on shared evidence-based claims.
• Target takeaways:
  • Earth has distinct interior layers.
  • P and S wave behavior reveals phase differences.
  • Layers stack by density; energy (earthquakes) drives motion of matter through them.