Earthquake Watch Skill

"Did we just have an earthquake?" gets asked within seconds of every tremor, and the USGS answers globally in near-real-time over keyless HTTPS. This skill knows the feed matrix (magnitude threshold × time window), filters to the place actually asked about, and frames magnitudes honestly — a 4.5 under a city and a 6.0 under the ocean are different events, and depth is half the story. For anything safety-shaped, it points at official emergency guidance rather than improvising any.

What This Skill Produces

• The events — matching quakes with magnitude, depth, location, and time (converted to the user's zone)
• The context read — what that magnitude/depth typically means for feeling it and damage, as bands not predictions
• The regional filter — the feed is global; the answer is about the place asked
• The command — exact curl, rerunnable

Required Inputs

Ask for these if not provided:

• Where — a place to filter around (the feeds are global; lat/lon of the place makes distance filtering honest)
• The window — "just now" (past hour feed), today, this week
• The threshold — significant-only vs. everything-they-can-feel (M2.5+) vs. research-grade (all)

Framework: The Feed Matrix and the Framing

1. The feeds — https://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/{mag}_{window}.geojson where mag ∈ significant, 4.5, 2.5, 1.0, all and window ∈ hour, day, week, month. "Just felt something" → 2.5_hour; "big ones today" → 4.5_day. Each feature: properties.mag, .place, .time (epoch ms), .url (event page), geometry.coordinates = [lon, lat, depth km].
2. Targeted queries beat feed-filtering for specific regions: https://earthquake.usgs.gov/fdsnws/event/1/query?format=geojson&latitude=35.68&longitude=139.69&maxradiuskm=300&starttime=2026-07-17&minmagnitude=3 — the fdsnws endpoint takes radius, time, magnitude bounds directly.
3. Magnitude bands, stated with every event: <3 rarely felt · 3–4 felt, no damage · 4–5 felt widely, minor damage possible near epicenter · 5–6 damage possible in built-up areas · 6–7 serious damage potential · 7+ major. Depth modifies everything: a shallow (<20km) M5 outfeels a 200km-deep M6 — say both numbers together.
4. Times get converted: feed times are epoch UTC; the answer speaks the user's local time ("14 minutes ago, 03:12 local").
5. The safety line: for "should I worry / is a bigger one coming" — aftershock probabilities and tsunami assessments belong to official agencies; link the event's USGS page and name the authoritative sources (national geological survey, tsunami warning centers) instead of improvising reassurance or alarm.

Output Format

Earthquakes: [region] — [window]

[The direct answer: "Yes — M4.7, 22km deep, 38km NE of [place], 14 min ago" or "No M2.5+ events near [place] in the past [window]."]

[Context band for the notable event(s) · aftershock/official-guidance line when safety is in the air]

Source: USGS real-time feeds · rerun: [exact curl] Informational — for safety decisions follow official emergency guidance, not this summary.

Quality Checks

• The direct yes/no answer leads before any table
• Depth appears next to magnitude on every quoted event
• Times are converted to the user's local zone with the relative offset
• Regional questions used radius filtering, not eyeballed global feeds
• Safety-shaped questions route to official sources by name

Anti-Patterns

• Do not answer from memory — seismicity is the definition of live data; fetch or hand over the command
• Do not quote magnitude without depth — half the felt-intensity story
• Do not predict aftershocks or all-clears — that's official-agency territory, linked not imitated
• Do not present the global significant feed as "nothing near you" — filter by place before saying no
• Do not dramatize small events or shrug at large ones — the bands calibrate the tone