Earthquake · reviewed by a seismologist
M 1.9md
Earthquake near Biola, CA
No earthquake was likely felt in Biola in the 24 hours to 5:39 am PST (13:39 UTC). The last one was M 5.7, 277 km (172 mi) NNE, at 3:08 pm PST on 9 December 2024, estimated intensity II (weak) in town; 8,416 felt reports to USGS. Every earthquake near Biola
This page: a magnitude 1.9 earthquake was recorded 10 km (6 mi) east-northeast of Biola, CA, at 9:39 pm PDT on 20 April 2021 (04:39 UTC), 20 km deep.
USGS: 10km ENE of Biola, CA
14 km (9 mi) WNW of Fresno, CA
- When
- 9:39 pm PDT on 20 April 2021 ()
- Where
- 10 km (6 mi) east-northeast of Biola, CA · earthquakes near Biola
- Magnitude
- M 1.9 (md)
- Depth
- 20 km below the surface
- Felt
- no reports yet
- Nearest
- Fresno County, 26 km ESE
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 2031 days ago
Earthquake alerts for Biola, CA
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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 Biola, 10 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: Old Fig Garden, Parkwood, Parksdale, Bonadelle Ranchos-Madera Ranchos, West Park, Madera.
How big was it?
This earthquake released about 21 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.
- Mineral, Virginia 2011 M 5.8 710,000× the energy of this one
- Magna, Utah 2020 M 5.7 500,000× the energy of this one
- Around the size people start to feel M 3.0 45× the energy of this one
- This earthquake M 1.9 about 21 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
No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.
Before 2016, the USGS record since 1900 lists no earthquake of M5 or more within 50 km.
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 36.8497, -119.9265. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Fresno County, CA | 26 km (16 mi) | ESE | earthquakes near Fresno County |
| Madera County, CA | 43 km (27 mi) | NNE | earthquakes near Madera County |
| Merced County, CA | 80 km (50 mi) | WNW | earthquakes near Merced County |
| Mariposa County, CA | 81 km (50 mi) | N | earthquakes near Mariposa County |
| Kings County, CA | 87 km (54 mi) | S | earthquakes near Kings County |
| San Benito County, CA | 107 km (66 mi) | WSW | earthquakes near San Benito County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
44 earthquakes have been recorded within 50 km since this one.
- 1.8 5km E of Bonadelle Ranchos-Madera Ranchos, CA
- 2.1 6km ENE of Bonadelle Ranchos-Madera Ranchos, CA
- 2.1 20km ENE of Le Grand, CA
- 2.0 6km NW of Friant, CA
- 2.1 5km ENE of Bonadelle Ranchos-Madera Ranchos, CA
- 2.1 6km ENE of Bonadelle Ranchos-Madera Ranchos, CA
- 2.2 12km N of Madera Acres, CA
- 2.2 3km SE of Yosemite Lakes, CA
- 2.1 6km ENE of Bonadelle Ranchos-Madera Ranchos, CA
- 2.2 21km ENE of Le Grand, CA
- 1.9 7km NE of Bonadelle Ranchos-Madera Ranchos, CA
- 2.2 7km NE of Bonadelle Ranchos-Madera Ranchos, CA
- 2.4 5km S of Lanare, CA
- 2.3 16km SSW of Fairmead, CA
- 2.2 22km ENE of Le Grand, 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.