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Terremoto moderato mag. 3.9 - 44 km a nord da Ukiah, Contea di Mendocino County, Contea di Kern, Stati Uniti, 23 Apr 4:18 am (GMT -7)

Terremoto moderato mag. 3.9 - 44 km a nord da Ukiah, Contea di Mendocino County, Contea di Kern, Stati Uniti, 23 Apr 4:18 am (GMT -7) Terremoto moderato mag. 3.9 - 44 km a nord da Ukiah, Contea di Mendocino County, Contea di Kern, Stati Uniti, 23 Apr 4:18 am (GMT -7)

Terremoto moderato magnitudine 3.9 a 7.4 km di profondità

23 Apr 11:22 UTC: Primo a segnalare: USGS dopo 4 minuti.
23 Apr 11:24: Magnitudine ricalcolata da 3.7 a 4.0.
23 Apr 14:02: Magnitudine ricalcolata da 4.0 a 3.9.
23 Apr 18:00: Profondità ricalcolata da 6.6 a 7.4 km (da 4.1 a 4.6 mi).
Update Fri, 23 Apr 2021, 11:27

Moderate 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)
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.

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Dettagli del sismo

Data e ora23 Apr 2021 11:18:40 UTC
Ora locale all'epicentro23 Apr 4:18 am (GMT -7)
StatusConfermato
Magnitudine3.9
Prof.7.4 km
Epicentro latitudine / longitudine39.52567°N / 123.0365°W (Contea di Mendocino, Contea di Kern, Stati Uniti)
Antipode39.526°S / 56.964°E
Intensità di scuotimentoScuotimento debole
Sentito6 rapporti
Fonte dati primariaUSGS (United States Geological Survey)
Vulcano più vicinoClear Lake (66 km / 41 mi)
Luoghi vicini24 km NNE da Potter Valley (pop: 646) | Mappa | Sismi nelle vicinanze
30 km ENE da Little Lake (pop: 4,860) | Mappa | Sismi nelle vicinanze
32 km NNE da Redwood Valley (pop: 1,730) | Mappa | Sismi nelle vicinanze
35 km SSE da Covelo (pop: 1,260) | Mappa | Sismi nelle vicinanze
42 km ESE da Laytonville (pop: 1,230) | Mappa | Sismi nelle vicinanze
44 km NNE da Ukiah (pop: 15,900) | Mappa | Sismi nelle vicinanze
50 km NNO da North Lakeport (pop: 3,310) | Mappa | Sismi nelle vicinanze
67 km E da Fort Bragg (Mendocino County) (pop: 7,290) | Mappa | Sismi nelle vicinanze
72 km NNO da Clearlake (Lake County) (pop: 15,200) | Mappa | Sismi nelle vicinanze
170 km NO da Sacramento (pop: 490,700) | Mappa | Sismi nelle vicinanze
Meteo all'epicentro al momento del sismoBroken Clouds 5.9°C (43 F), humidity: 81%, wind: 2 m/s (3 kts) from NE
Energia sismica rilasciata stimata4.5 x 1010 joules (12.4 MWh, equivalent to 10.7 tons of TNT) | about seismic energy
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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.
Mag.Prof.UbicazioneFonte
3.97.4 km15km NNW of Lake Pillsbury, CA, USAUSGS
3.45 kmNORTHERN CALIFORNIA, USAEMSC

Seismograms

Seismic station: Marconi Conference Center, Marshall, CA, USA (MCCM/BK network) | Distance from quake: 154 km / 96 mi | Show on map | Station Info
Seismic station Marconi Conference Center, Marshall, CA, USA: vertical movement plot around time of quake (source: IRIS/BUD)
Seismogram (vertical component) around time of quake. Thin dotted red line indicates time of quake. Seismic waves arrive some time later, depending on distance. Source: IRIS Buffer of Uniform Data (BUD) webtool
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User reports for this quake (6)

User reports estimate the perceived ground shaking intensity according to the MMI (Modified Mercalli Intensity) scale.
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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

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