QuakeIndex

Earthquake · reviewed by a seismologist

M 4.8mw

Earthquake near Blue Lake, CA

No earthquake was likely felt in Blue Lake in the 24 hours to 11:50 pm PST (07:50 UTC). The last one was M 5.0, 145 km (90 mi) WSW, at 8:56 pm PST on 4 November 2026, estimated intensity II (weak) in town; 145 felt reports to USGS. Every earthquake near Blue Lake

This page: a magnitude 4.8 earthquake was recorded 19 km (12 mi) south-southeast of Blue Lake, CA, at 4:09 pm PDT on 21 July 2016 (23:09 UTC), 26 km deep. 1,087 people have reported feeling it to USGS.

USGS: 19km SSE of Blue Lake, CA

4:09 pm PDT, Jul 21, 2016 · · 26 km deep · released about 250 tons of TNT

Every earthquake near Blue Lake Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Humboldt County 3 kmTrinity County 66 kmDel Norte County 114 km
Distance rings around the epicentre, with the nearest towns at their true direction and later quakes as coloured dots. Not a shaking map — see the USGS ShakeMap for that.
When
4:09 pm PDT on 21 July 2016 ()
Where
19 km (12 mi) south-southeast of Blue Lake, CA · earthquakes near Blue Lake
Magnitude
M 4.8 (mw)
Depth
26 km below the surface
Felt
1,087 reports · strongest reported intensity V
Measured shaking
intensity V (ShakeMap)
USGS impact alert
green
Tsunami
USGS flagged this event for tsunami evaluation. Follow tsunami.gov for official messages.
Nearest
Humboldt County, 3 km SW
Nearest mapped fault
Mad River fault, 4 km from its surface trace — near is not the same as on
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2820 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon.

At this magnitude and depth, people at rest would likely notice it out to about 169 km (105 mi) from the epicentre. In Blue Lake, 19 km away, the estimate is intensity IV (light). Estimated from magnitude, depth and distance with the intensity equation USGS Did You Feel It? uses; felt reports, where there are any, are the measurement.

Likely felt in: Bayside 20 km, intensity IV · Eureka 24 km, intensity III · Humboldt Hill 25 km, intensity III · Fortuna 26 km, intensity III · McKinleyville 30 km, intensity III · Rio Dell 31 km, intensity III · Willow Creek 32 km, intensity III · Ferndale 35 km, intensity III. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 250 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.8 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 680× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 31× the energy of this one
  3. Magna, Utah 2020 M 5.7 22× the energy of this one
  4. This earthquake M 4.8 about 250 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 520× more

Energy from the Gutenberg–Richter relation (log10E = 1.5M + 4.8), rounded to two figures; bar length is magnitude, which is already a logarithm of energy. Magnitudes of past earthquakes from the USGS catalogue.

For this area

The largest earthquake within 50 km (31 mi) since our catalogue begins in 2016. No other earthquake of M4 or more has been recorded this close in that time.

Before 2016, the USGS record lists 16 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.5 The 1932 Eureka, California Earthquake · 33 km W of this epicentre
  2. 6.4 The 1954 Eureka-Arcata, California Earthquake · 14 km N of this epicentre
  3. 6.0 Near Rio Dell, California · 36 km SW of this epicentre
  4. 5.8 Near Eureka, California · 12 km NW of this epicentre
  5. 5.6 15 km SW of Burnt Ranch, California · 23 km E of this epicentre

Since 2016: the QuakeIndex catalogue (US, M1.5+), built from the USGS FDSN event service. Before 2016: USGS ComCat, M5+ from 1900. Distances are between epicentres. This is the record, not a forecast.

Where

Epicentre 40.7243, -123.8918. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Humboldt County, CA 3 km (2 mi) SW earthquakes near Humboldt County
Trinity County, CA 66 km (41 mi) E earthquakes near Trinity County
Del Norte County, CA 114 km (71 mi) N earthquakes near Del Norte County
Siskiyou County, CA 149 km (92 mi) NE earthquakes near Siskiyou County

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

42 earthquakes have been recorded within 50 km since this one.

  1. 1.7 7 km ESE of Blue Lake, California
  2. 2.1 19 km NNE of Redcrest, California
  3. 2.8 19 km NNE of Redcrest, California
  4. 2.0 17 km SW of Scotia, California
  5. 1.8 16 km NE of Hydesville, California
  6. 1.9 14 km SW of Scotia, California
  7. 1.8 17 km ESE of Blue Lake, California
  8. 2.1 18 km ESE of Indianola, California
  9. 2.2 1 km NNE of Humboldt Hill, California
  10. 2.0 9 km WNW of Hyampom, California
  11. 2.9 13 km NE of Trinity Village, California
  12. 2.6 9 km NE of Burnt Ranch, California
  13. 1.8 15 km W of Weott, California
  14. 3.1 12 km W of Weott, California
  15. 2.3 16 km SSW of Ferndale, California

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of . QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.

On USGS

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.