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Moderate mag. 4.9 earthquake - 39 km southwest of Ayutla de los Libres, Guerrero, Mexico, on Monday, Sep 20, 2021 at 4:36 am (GMT -5)

This quake was likely an aftershock of the 7.1 quake North Pacific Ocean, 8 km south of Acapulco, Guerrero, Mexico, Sep 7, 2021 8:47 pm (GMT -5), which had occurred 12 days earlier.
Moderate mag. 4.9 earthquake - 39 km southwest of Ayutla de los Libres, Guerrero, Mexico, on Monday, Sep 20, 2021 at 4:36 am (GMT -5) Moderate mag. 4.9 earthquake - 39 km southwest of Ayutla de los Libres, Guerrero, Mexico, on Monday, Sep 20, 2021 at 4:36 am (GMT -5)

Moderate magnitude 4.9 earthquake at 25 km depth

20 Sep 09:54 UTC: First to report: VolcanoDiscovery after 18 minutes.
20 Sep 10:00: Now using data updates from SSN

Earthquake details

Date & timeSep 20, 2021 09:36:33 UTC
Local time at epicenterMonday, Sep 20, 2021 at 4:36 am (GMT -5)
Depth25.0 km
Epicenter latitude / longitude16.65°N / 99.25°W (San Marcos, Guerrero, Mexico)
Antipode16.65°S / 80.75°E
Shaking intensityWeak shaking
Felt5 reports
Primary data sourceSSN (Servicio Sismológico Nacional)
Nearby towns and cities3 km (2 mi) NW of Boca del Rio (pop: 492) | Show on map | Quakes nearby
13 km (8 mi) S of Las Vigas (pop: 4,500) | Show on map | Quakes nearby
16 km (10 mi) WSW of Florencio Villarreal (Cruz Grande) (pop: 11,800) | Show on map | Quakes nearby
22 km (14 mi) SE of San Marcos (pop: 13,300) | Show on map | Quakes nearby
29 km (18 mi) W of Copala (pop: 6,620) | Show on map | Quakes nearby
39 km (24 mi) SSW of Ayutla de los Libres (pop: 15,400) | Show on map | Quakes nearby
74 km (46 mi) ESE of Acapulco (pop: 673,500) | Show on map | Quakes nearby
90 km (56 mi) W of Ometepec (pop: 24,100) | Show on map | Quakes nearby
104 km (64 mi) SSE of Chilpancingo de los Bravo (pop: 187,300) | Show on map | Quakes nearby
309 km (192 mi) S of Mexico (Ciudad de México) (pop: 12,294,200) | Show on map | Quakes nearby
Weather at epicenter at time of quakeOvercast Clouds 24.9°C (77 F), humidity: 88%, wind: 2 m/s (3 kts) from N
Estimated seismic energy released1.4 x 1012 joules (392 megawatt hours, equivalent to 338 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.
4.925 kmMexico: 22 Km Al SURESTE De SAN MARCOS, GROSSN
4.520 kmGuerrero, MexicoGFZ
4.610 km7 Km SW of Cruz Grande, MexicoUSGS


Seismic station: TLAPA (TLIG/MX network) | Distance from quake: 125 km / 78 mi | Show on map | Station Info
Seismic station TLAPA: 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. Bandpass filter applied: 0.2-10.0 Hz. Source: IRIS Buffer of Uniform Data (BUD) webtool
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User reports for this quake (7)

User reports estimate the perceived ground shaking intensity according to the MMI (Modified Mercalli Intensity) scale.
Leave a comment if you find a particular report interesting or want to add to it.
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Send your own user report!
near Cruz Grande, Florencio Villarreal, Guerrero (2.4 km ENE of epicenter) [Map] / Weak shaking (MMI III) / rattling, vibrating / 1-2 s : Se sintió cómo 3 brincos como si pasara un Trailer pesado aquí afuera en realidad fue muy rápido y por una parte pensamos que ya estábamos siscados pero en si si paso pues los vidrios de las ventanas y el balcón sonaron | One user found this interesting.  
Copala, Guerrero (30.2 km E of epicenter) [Map] / Moderate shaking (MMI V) / vibration and rolling / very short : Estaba acostada en un colchon sobre el piso, escuche la sacudida de los muebles y del espejo, sentí que estuvo medio fuerte, pero duro muy poco  
Cdmx / not felt (reported through our app)
Estado de México / not felt (reported through our app)
Yautepec Morelos México / Light shaking (MMI IV) / horizontal (sideways) swinging / 5-10 s : Me despertó el movimiento y el crujir de mi edificio  
Ciudad de México / Very weak shaking (MMI II) : Movimiento ligero de objetos colgantes  
Ixtepec, Oaxaca / Very weak shaking (MMI II) / 2-5 s : Agitación de la ventana de mi habitación y balanceo en mi habitación muy leve  

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