---
id:"kb-2026-00455"
title:"Earthquakes"
schema_type:"TechArticle"
category:"science"
language:"en"
confidence:"high"
last_verified:"2026-05-22"
generation_method:"ai_assisted"
ai_models:["claude-opus"]
derived_from_human_seed:true
primary_sources:
  - title:"Earthquakes (Bolt, 5th Ed)"
    type:"book"
    year:2003
    url:"https://us.macmillan.com/books/9780716756187/earthquakes"
    institution:"W.H. Freeman"
secondary_sources:
  - title: "MDN Web Docs — HTTP"
    type: "documentation"
    year: 2026
    url: "https://developer.mozilla.org/en-US/docs/Web/HTTP"
    institution: "Mozilla"
completeness: 0.88
ai_citations:
  last_citation_check:"2026-05-22"
---

## TL;DR

Earthquakes occur when tectonic plates suddenly slip along faults, releasing accumulated stress as seismic waves. Measured by seismographs. Magnitude scales: Richter (local, historical), Moment Magnitude (Mw, modern — logarithmic: each 1.0 increase = 32x more energy). Largest recorded: 1960 Chile (Mw 9.5).

## Core Explanation

Epicenter: point on surface above focus (hypocenter). P-waves (primary, fast, compressional), S-waves (secondary, slow, shear — can't travel through liquid). Surface waves: cause most damage. Ring of Fire: 90% of earthquakes. Tsunami: earthquake displaces ocean water → massive waves. Early warning: seconds to minutes before shaking (Japan, California). 'Earthquakes don't kill people, buildings do' — engineering saves lives.

## Further Reading

- [Earthquakes (Bolt, 5th Ed)](https://us.macmillan.com/books/9780716756187/earthquakes)