# Quakes99 — question guides

> Explore significant earthquakes by magnitude, depth, place and related USGS events.

This file covers /task-guides/. Use the site-wide reference at https://quakes99.com/llms.txt for the broader site. Canonical website: https://quakes99.com/. Documentation reviewed 2026-10-18; underlying records have their own dates. Fields to verify when supplied: USGS event identifier; event time; magnitude type; depth and units. Magnitude, intensity and depth describe different properties. A magnitude alone does not determine damage at a location. This is read-only discovery; robots rules and source licences still apply.

## Start here

- [Agent instructions](https://quakes99.com/task-guides/agent-use.md): How to find a record, use native search, interpret missing data and cite an answer.
- [Data context](https://quakes99.com/task-guides/data-context.md): Site-specific identity fields, coverage, dates and limitations.
- [Source guide](https://quakes99.com/task-guides/sources.md): Claim-to-source links for published guidance.
- [Task guide](https://quakes99.com/task-guides/index.md): Practical steps and links into existing site tools.

## Existing site tools

- [Start a search on quakes99.com](https://quakes99.com/): Existing public page; use its visible controls and source dates.
- [About this site](https://quakes99.com/about): Existing public page; use its visible controls and source dates.
- [Corrections](https://quakes99.com/corrections): Existing public page; use its visible controls and source dates.
- [Snapshot events](https://quakes99.com/recent): Existing public page; use its visible controls and source dates.

## Published question guides

- [What is the difference between the Richter scale and the Mercalli scale?](https://quakes99.com/task-guides/richter-scale-vs-mercalli-scale/index.md): Source-linked answer; published 2026-10-18.
- [How bad is a 6.3 earthquake?](https://quakes99.com/task-guides/how-bad-is-a-6-3-earthquake/index.md): Source-linked answer; published 2026-10-18.

## Optional

- [Machine-readable action index](https://quakes99.com/task-guides/agent.json): Observed GET form, fixed navigation, document index and coverage metadata.
- [Expanded reference](https://quakes99.com/task-guides/llms-full.txt): Read when the individual documents are insufficient; includes published article text.
- [Guide sitemap](https://quakes99.com/task-guides/sitemap.xml): Indexable human-readable guide URLs only.