QuakeIndex

Earthquake · reviewed by a seismologist

M 1.7ml

18km W of Ludlow, CA

Yes. A magnitude 1.7 earthquake was recorded 18km W of Ludlow, CA, at 1:54 pm PDT on 26 August 2017 (20:54 UTC), 3.2 km deep.

· 3.2 km deep · released about 9.3 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N San Bernardino County 23 kmRiverside 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
Magnitude
M 1.7 (ml)
Depth
3.2 km below the surface
Felt
no reports yet
Nearest
San Bernardino County, 23 km NE
Nearest mapped fault
Pisgah-Bullion fault, 5 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 3304 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

At this magnitude and depth, people at rest would likely notice it out to about 11 km (7 mi) from the epicentre. 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.

How big was it?

This earthquake released about 9.3 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.7 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,600,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,100,000× the energy of this one
  3. Around the size people start to feel M 3.0 100× the energy of this one
  4. This earthquake M 1.7 about 9.3 lb of TNT

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 since 2016 was M 4.3 on 2016-02-20 — about 9,400 times the energy of this one.

Before 2016, the USGS record lists 14 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.1 The 1999 Hector Mine, California Earthquake · 14 km SE of this epicentre
  2. 6.5 The 1947 Manix, California Earthquake · 34 km NNW of this epicentre
  3. 5.8 13km WSW of Ludlow, CA · 7 km ESE of this epicentre
  4. 5.5 17km WSW of Amboy, CA · 46 km ESE of this epicentre
  5. 5.4 26km NNW of Yucca Valley, CA · 43 km SSW 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 34.7090, -116.3563. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
San Bernardino County, CA 23 km (14 mi) NE earthquakes near San Bernardino County
Riverside County, CA 114 km (71 mi) SSE earthquakes near Riverside County

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

Aftershocks so far

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

  1. 1.6 23km N of Yucca Valley, CA
  2. 1.7 22km N of Yucca Valley, CA
  3. 1.6 23km N of Yucca Valley, CA
  4. 1.7 6km WSW of Ludlow, CA
  5. 1.9 19km SSE of Fort Irwin, CA
  6. 1.9 24km W of Ludlow, CA
  7. 2.2 17km WSW of Ludlow, CA
  8. 1.8 22km N of Yucca Valley, CA
  9. 1.9 7km WSW of Ludlow, CA
  10. 2.0 19km NE of Big Bear City, CA
  11. 3.0 7km WSW of Ludlow, CA
  12. 1.6 25km WNW of Ludlow, CA
  13. 2.0 14km NE of Ludlow, CA
  14. 3.7 13km NE of Ludlow, CA
  15. 1.6 39km WSW of Ludlow, CA

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.