# Session 1 — Why Does the Earth Make Noise?
Format E — Open Problem
Week 1
Relevance: Earthquake early warning
*Opening the field · Hook: Tōhoku seismogram · ShakeAlert*
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```{dropdown} Hook (0 – 7 min)
Show the IRIS MUSTANG global visualization of the 2011 Tōhoku earthquake — no audio, no explanation. Ask:
**"What is this? What does a global seismogram record that a single station can't?"**
Pair-share 90 seconds. Take 3–4 responses without correcting them.
```
```{dropdown} Discussion (7 – 42 min)
**Central question:** *"Seismic waves travel through the entire planet in under 20 minutes. What does that mean for what we can learn about Earth's interior — and for how fast we can warn people?"*
- Discuss ShakeAlert, currently deployed in the PNW. What wave physics does it use? What are its limits?
- What would you need to improve it with what you're learning this week?
- Leave space for students to be wrong — explore the wrongness.
**Open problem thread:** Why is earthquake early warning still imperfect if seismic waves travel at known speeds? What would a perfect system require?
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```{dropdown} Relevance
**Hazard:** USGS estimates ~\$15B annual US losses from earthquakes; 50% of US states have significant future shaking potential (USGS EHP Decadal Strategy, 2024). The wave physics from lecture is the foundation of every hazard tool.
**Basic science:** Everything we know about the liquid outer core and solid inner core came from seismic shadow zones — there is no drill that reaches it. The same waves that warn people about earthquakes also reveal the planet's deep structure.
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```{dropdown} Go Deeper
IRIS "How Does a Seismometer Work?" animations · USGS ShakeAlert
**One name to look up:** Dr. Doug Given, USGS — ShakeAlert coordinator. What does his team's day-to-day work look like?
```