Terremoto moderado mag. 3.9 - 28 miles NNE of Ukiah, Mendocino County, California, USA, Friday, 23 Apr. 2021 -
Terremoto moderado magnitud 3.9 at 7 km depth
23 Apr 11:22 UTC: Primero en informar: USGS después de 4 minutos.
23 Apr 11:24: Magnitud recalculada de 3.7 a 4.0.
23 Apr 14:02: Magnitud recalculada de 4.0 a 3.9.
23 Apr 18:00: Profundidad recalculada de 6.6 a 7.4 km (de 4.1 a 4.6 mi).
Update Fri, 23 Apr 2021, 11:27Moderate magnitude 4.0 quake hits 28 miles northeast of Ukiah, California, United States early morning
4.0 quake 23 Apr 4:18 am (GMT -7)
The United States Geological Survey reported a magnitude 4.0 quake in the United States near Ukiah, Mendocino County, California, only 8 minutes ago. The earthquake hit early morning on Friday 23 April 2021 at 4:18 am local time at a very shallow depth of 4.1 miles. The exact magnitude, epicenter, and depth of the quake might be revised within the next few hours or minutes as seismologists review data and refine their calculations, or as other agencies issue their report.
Our monitoring service identified a second report from the European-Mediterranean Seismological Centre (EMSC) which listed the quake at magnitude 4.0 as well.
Based on the preliminary seismic data, the quake should not have caused any significant damage, but was probably felt by many people as light vibration in the area of the epicenter.
Weak shaking might have been felt in Potter Valley (pop. 650) located 15 miles from the epicenter, Willits (pop. 4,900) 19 miles away, Brooktrails (pop. 3,200) 19 miles away, and Redwood Valley (pop. 1,700) 20 miles away.
Other towns or cities near the epicenter where the quake might have been felt as very weak shaking include Covelo (pop. 1,300) located 22 miles from the epicenter, Ukiah (pop. 15,900) 28 miles away, Nice (pop. 2,700) 30 miles away, and Clearlake (pop. 15,200) 45 miles away.
Download the Volcanoes & Earthquakes app
to get one of the fastest seismic alerts online:Android
Fecha & hora: 23 Apr 2021 11:18:40 UTC -
Hora local al epicentro:
23 Apr 4:18 am (GMT -7)
Profundidad: 7.4 km
Epicentro latitud / longitud: 39.52567°N / 123.0365°W
(Condado de Mendocino
, Condado de Kern
, Estados Unidos
Volcán mas cercano: Clear Lake
(66 km / 41 mi)
Nearby towns and cities:24 km al NNE de Potter Valley
(pop: 646) --> ¡Vea sismos cercanos!30 km al ENE de Willits
(pop: 4,860) --> ¡Vea sismos cercanos!32 km al NNE de Redwood Valley
(pop: 1,730) --> ¡Vea sismos cercanos!35 km al SSE de Covelo
(pop: 1,260) --> ¡Vea sismos cercanos!42 km al ESE de Laytonville
(pop: 1,230) --> ¡Vea sismos cercanos!44 km al NNE de Ukiah
(pop: 15,900) --> ¡Vea sismos cercanos!50 km al NNO de North Lakeport
(pop: 3,310) --> ¡Vea sismos cercanos!72 km al NNO de Clearlake (Lake County)
(pop: 15,200) --> ¡Vea sismos cercanos!124 km al NNO de Santa Rosa
(pop: 175,000) --> ¡Vea sismos cercanos!170 km al NO de Sacramento
(pop: 490,700) --> ¡Vea sismos cercanos!
Weather at epicenter at time of quake:
Broken Clouds 5.9°C
(43 F), humidity: 81%, wind: 2 m/s (3 kts) from NE
Fuente primaria de datos: USGS
(United States Geological Survey)
Energía liberada estimada: 4.5 x 1010
joules (12.4 megawatt hours, equivalent to 10.7 tons of TNT) More info
Data for the same earthquake reported by different agencies
Info: The more agencies report about the same quake and post similar data, the more confidence you can have in the data. It takes normally up to a few hours until earthquake parameters are calculated with near-optimum precision.
|3.9||7.4 km||15km NNW of Lake Pillsbury, CA, USA||USGS|
|3.4||5 km||NORTHERN CALIFORNIA, USA||EMSC|
User reports for this quake (6)
Leave a comment if you find a particular report interesting or want to add to it.
Flag as inappropriate.
Mark as helpful or interesting.
Send your own user report!
San Jose, California 95148 / Light shaking (MMI IV) / single lateral shake / 2-5 s : Woke me up from sleep, a bag of items on top of another bag of items fell over. Then the wall behind me seemed to be jolted once northeasterly, creaked, rumbled and stopped. From jolt to stop was 2 seconds tops.
Orange, CA / Light shaking (MMI IV) / single lateral shake / 5-10 s
Nas Lemoore (455.8 km SE of epicenter) [Map] / Very weak shaking (MMI II) / horizontal (sideways) swinging / 5-10 s
San Jose / Very weak shaking (MMI II) / single vertical bump / 1-2 s
5726 Ridgewood Road Willits, CA (27.6 km SW of epicenter) [Map] / Light shaking (MMI IV) / horizontal (sideways) swinging / 2-5 s : Woke up to house shaking.
93041 / Light shaking (MMI IV) / rattling, vibrating / 2-5 s
Earlier earthquakes in the same area
Click here to search our database for earlier earthquakes in the same area since 1900!