Earthquake · reviewed by a seismologist
M 1.7md
Earthquake near Morgan Hill, CA
No earthquake was likely felt in Morgan Hill in the 24 hours to 1:17 pm PST (21:17 UTC). The last one was M 2.6, 20 km (13 mi) N, at 12:38 pm PDT on 27 October 2026, estimated intensity II (weak) in town; 8 felt reports to USGS. Every earthquake near Morgan Hill
This page: a magnitude 1.7 earthquake was recorded 22 km (14 mi) north-northeast of Morgan Hill, CA, at 3:39 am PDT on 28 September 2018 (10:39 UTC), 7.8 km deep.
USGS: 22km NNE of Morgan Hill, CA
23 km (14 mi) E of San Jose, CA
- When
- 3:39 am PDT on 28 September 2018 ()
- Where
- 22 km (14 mi) north-northeast of Morgan Hill, CA · earthquakes near Morgan Hill
- Magnitude
- M 1.7 (md)
- Depth
- 7.8 km below the surface
- Felt
- no reports yet
- Nearest
- Santa Clara County, 16 km SW
- Nearest mapped fault
- Greenville fault, 7 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 2967 days ago
Earthquake alerts for Morgan Hill, CA
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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 9 km (6 mi) from the epicentre. In Morgan Hill, 22 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: East Foothills, San Martin.
How big was it?
This earthquake released about 9.6 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.
- Mineral, Virginia 2011 M 5.8 1,600,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,100,000× the energy of this one
- Around the size people start to feel M 3.0 99× the energy of this one
- This earthquake M 1.7 about 9.6 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 4,300 times the energy of this one.
Before 2016, the USGS record lists 23 earthquakes of M5 or more within 50 km; the five largest:
- 6.9 The 1989 Loma Prieta, California Earthquake · 42 km SW of this epicentre
- 6.5 Near Morgan Hill, California · 23 km SSW of this epicentre
- 6.2 Near San Jose, California · 22 km W of this epicentre
- 6.2 The 1984 Morgan Hill, California Earthquake · 11 km W of this epicentre
- 6.1 Near San Jose, California · 25 km WSW 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 37.3107, -121.5535. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Santa Clara County, CA | 16 km (10 mi) | SW | earthquakes near Santa Clara County |
| Alameda County, CA | 49 km (30 mi) | NW | earthquakes near Alameda County |
| Santa Cruz County, CA | 52 km (32 mi) | SW | earthquakes near Santa Cruz County |
| Stanislaus County, CA | 56 km (35 mi) | ENE | earthquakes near Stanislaus County |
| San Mateo County, CA | 73 km (45 mi) | W | earthquakes near San Mateo County |
| San Joaquin County, CA | 74 km (46 mi) | NNE | earthquakes near San Joaquin County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
51 earthquakes have been recorded within 50 km since this one.
- 1.9 10km E of Alum Rock, CA
- 2.5 16km N of Morgan Hill, CA
- 2.9 28km E of Alum Rock, CA
- 2.6 26km W of Los Banos, CA
- 1.6 8km NE of Gilroy, CA
- 2.2 10km ENE of Milpitas, CA
- 2.6 9km ENE of Milpitas, CA
- 1.6 2km E of Aromas, CA
- 1.5 22km ENE of Alum Rock, CA
- 2.0 15km E of Seven Trees, CA
- 1.8 9km NE of Milpitas, CA
- 2.4 10km ESE of Gilroy, CA
- 1.5 2km ENE of Aromas, CA
- 1.9 8km NE of Gilroy, CA
- 1.8 18km NE of San Martin, 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.