Earthquake · reviewed by a seismologist
M 1.6md
Earthquake near Modesto, CA
No earthquake was likely felt in Modesto in the 24 hours to 9:53 pm PST (05:53 UTC). The last one was M 3.5, 47 km (29 mi) WSW, at 7:21 am PDT on 27 September 2026, estimated intensity II (weak) in town; 8 felt reports to USGS. Every earthquake near Modesto
This page: a magnitude 1.6 earthquake was recorded 34 km (21 mi) southwest of Modesto, CA, at 10:09 am PDT on 23 April 2018 (17:09 UTC), less than 1 km deep.
USGS: 14km SSW of Westley, CA
49 km (31 mi) ENE of San Jose, CA · 33 km (21 mi) SW of Modesto, CA
- When
- 10:09 am PDT on 23 April 2018 ()
- Where
- 34 km (21 mi) southwest of Modesto, CA · earthquakes near Modesto
- Magnitude
- M 1.6 (md)
- Depth
- -0.0 km below the surface
- Felt
- no reports yet
- Nearest
- Stanislaus County, 29 km ENE
- Nearest mapped fault
- Great Valley thrust fault system, 9 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 3124 days ago
Earthquake alerts for Modesto, CA
Get a notification in this browser when USGS records an earthquake near Modesto, CA. No account or email needed.
Alerts are on for .
Not a warning. An alert comes after USGS publishes a quake, usually minutes after the shaking. For early warning use ShakeAlert, through your phone's Wireless Emergency Alerts or the MyShake app.
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 12 km (7 mi) from the epicentre. In Modesto, 34 km away, the estimate is intensity I (not felt). 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: Patterson, Newman, Riverdale Park, West Modesto.
How big was it?
This earthquake released about 9 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.6 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 1,700,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,200,000× the energy of this one
- Around the size people start to feel M 3.0 110× the energy of this one
- This earthquake M 1.6 about 9 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 4.1 on 2017-10-10 — about 4,600 times the energy of this one.
Before 2016, the USGS record lists 7 earthquakes of M5 or more within 50 km; the five largest:
- 6.5 Near Morgan Hill, California · 48 km SW of this epicentre
- 6.2 Near San Jose, California · 48 km WSW of this epicentre
- 6.2 The 1984 Morgan Hill, California Earthquake · 37 km WSW of this epicentre
- 5.8 The 1979 Coyote Lake, California Earthquake · 42 km SSW of this epicentre
- 5.7 15 km NE of East Foothills, California · 35 km W 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 37.4405, -121.2885. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Stanislaus County, CA | 29 km (18 mi) | ENE | earthquakes near Stanislaus County |
| Santa Clara County, CA | 43 km (27 mi) | SW | earthquakes near Santa Clara County |
| San Joaquin County, CA | 55 km (34 mi) | N | earthquakes near San Joaquin County |
| Merced County, CA | 57 km (35 mi) | ESE | earthquakes near Merced County |
| Alameda County, CA | 60 km (37 mi) | WNW | earthquakes near Alameda County |
| Contra Costa County, CA | 79 km (49 mi) | NW | earthquakes near Contra Costa County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
53 earthquakes have been recorded within 50 km since this one.
- 1.8 11km ESE of Sunol, CA
- 2.0 20km E of Alum Rock, CA
- 1.9 8km SE of Livermore, CA
- 1.6 14km E of Seven Trees, CA
- 1.7 8km ENE of Gilroy, CA
- 1.7 17km SE of Livermore, CA
- 1.8 9km NNE of Alum Rock, CA
- 1.9 10km ESE of Sunol, CA
- 1.6 11km NE of Milpitas, CA
- 2.8 9km ENE of Milpitas, CA
- 2.4 24km SW of Gustine, CA
- 2.5 9km NE of San Martin, CA
- 3.4 9km ENE of Milpitas, CA
- 1.8 23km SW of Gustine, CA
- 1.6 8km NE of Alum Rock, 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
- The official USGS event page — the source of record for every value above
- Did you feel it? Report it to USGS — reports go to USGS, not to us
- ShakeMap for this event, when USGS has produced one
QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.