QuakeWatch | Earthquake Impact

How to read this map

Hazard / signal: recent earthquake hazard
Exposure: nearby population
Consequence / vulnerability: social vulnerability / official impact products when available

Official/source values remain distinct from MitchellCo derived screening scores or estimates.

Which recent earthquakes overlap the largest and most socially vulnerable populations?

USGS earthquake data renders first. CDC county geometry/SVI loads independently. State population totals are checked in a small 15-day local cache before CDC is called; the cache does not replace the county geometry/SVI query needed by this map.

Data health

USGS M2.5+ earthquakesLoading

CDC county / SVILoading

Selected-event ShakeMapOn demand

Waiting for live data…

LayersUSGS earthquake epicentersDerived county concernSelected USGS ShakeMap MMI contours

Legend

M2.5–3.9

M4.0–5.9

M6.0+

Official ShakeMap intensity contour

Highest derived community concern

#	County	Nearest quake	Score
Waiting for earthquake and county layers…

How the derived score works

Event hazard, max 55
magnitude contribution = clamp(0,55,20 × (M − 2.5))
shallow-depth bonus = max(0,10 × (1 − depth/50 km))
event hazard capped at 55

Distance attenuation
R = clamp(30,300,20 × 2^(M − 3)) km
attenuation = exp(−distance/R)

Exposure, max 25
min(25, 4.2 × log10(population + 1))

Vulnerability, max 20
20 × overall SVI percentile rank

Concern
attenuation × (hazard + exposure + vulnerability), capped at 100.

Refresh & reliability

USGS's seven-day GeoJSON feed refreshes every 2 minutes. CDC SVI is static 2022 vintage and loads only on region changes. Broad raw responses are not stored in localStorage. Only normalized state population totals use versioned 15-day localStorage entries. Cache access/write failure is non-fatal. CDC and ShakeMap failures cannot cancel the earthquake feed or other UI work. Retries are bounded exponential backoff for transient/network failures only.

Sources & attribution

USGS Earthquake Hazards Program GeoJSON feeds: M2.5+ past 7 days.

USGS ShakeMap: on-demand official shaking contours.

USGS PAGER: official rapid-impact alert when available.

CDC/ATSDR SVI 2022 county layer: county population and SVI percentile rank.

Basemap © OpenStreetMap contributors.