QuakeIndex

Earthquake · reviewed by a seismologist

M 1.9ml

Earthquake near Topanga, CA

No earthquake was likely felt in Topanga in the 24 hours to 6:03 am PST (14:03 UTC). The last one was M 2.3, 18 km (11 mi) N, at 9:45 am PST on 7 November 2026, estimated intensity II (weak) in town; 26 felt reports to USGS. Every earthquake near Topanga

This page: a magnitude 1.9 earthquake was recorded 3 km (2 mi) west of Topanga, CA, at 11:47 am PDT on 31 August 2023 (18:47 UTC), 17 km deep.

USGS: 3 km W of Topanga, CA

22 km (14 mi) WNW of Los Angeles, CA · 15 km (9 mi) NW of Santa Monica, CA

11:47 am PDT, Aug 31, 2023 · · 17 km deep · released about 19 lb of TNT

Every earthquake near Topanga Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Los Angeles County 36 kmVentura County 55 kmOrange County 91 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
11:47 am PDT on 31 August 2023 ()
Where
3 km (2 mi) west of Topanga, CA · earthquakes near Topanga
Magnitude
M 1.9 (ml)
Depth
17 km below the surface
Felt
no reports yet
Nearest
Los Angeles County, 36 km ENE
Nearest mapped fault
Malibu Coast fault, 6 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 1169 days ago

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

At this magnitude and depth it was probably too small to be felt, even directly above it. In Topanga, 3 km away, the estimate is intensity II (weak). 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.

Earthquakes near other towns within 30 km: Hidden Hills, Agoura, Agoura Hills, Santa Monica, Malibu, Oak Park.

How big was it?

This earthquake released about 19 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.9 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 790,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 560,000× the energy of this one
  3. Around the size people start to feel M 3.0 50× the energy of this one
  4. This earthquake M 1.9 about 19 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 2021-09-18 — about 4,100 times the energy of this one.

Before 2016, the USGS record lists 23 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.7 Northridge, California, earthquake · 16 km NNE of this epicentre
  2. 6.6 1971 San Fernando Earthquake, California · 44 km NNE of this epicentre
  3. 5.9 1km ENE of Granada Hills, California · 24 km NNE of this epicentre
  4. 5.8 10km SSW of Agua Dulce, CA · 44 km NNE of this epicentre
  5. 5.8 10km SSW of Agua Dulce, CA · 44 km NNE 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 34.0885, -118.6328. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Los Angeles County, CA 36 km (22 mi) ENE earthquakes near Los Angeles County
Ventura County, CA 55 km (34 mi) WNW earthquakes near Ventura County
Orange County, CA 91 km (57 mi) ESE earthquakes near Orange 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 12 km WNW of Malibu, CA
  2. 1.8 13 km WNW of Malibu, CA
  3. 2.2 10 km NW of Malibu, CA
  4. 2.4 11 km WNW of Malibu, CA
  5. 3.0 11 km WNW of Malibu, CA
  6. 2.3 11 km WNW of Malibu, CA
  7. 4.6 11 km WNW of Malibu, CA
  8. 1.6 2 km NW of Tarzana, CA
  9. 2.3 4 km SW of Sherman Oaks, CA
  10. 1.5 3 km NNE of Granada Hills, CA
  11. 2.0 1 km SSE of Century City, CA
  12. 2.0 5 km ESE of Malibu, CA
  13. 2.0 21 km W of Palos Verdes Estates, CA
  14. 2.3 4 km SSW of Compton, CA
  15. 2.3 8 km WNW of Malibu, 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.