Earthquakes in the DR

[CFA123]

Nothing posted on the USGS earthquake site yet. Not surprising, it's Sunday and the DR is not a priority zone for USGS monitoring and reporting.

Further to the discussion of a magnitude 6+ event, should one occur within the DR and for the sake of argument in the location of this quake near Imbert, it would be an oh my god event and I suspect a crack in my wall would be the least of my worries.

Such a quake would be 200 times stronger than what we felt just after 2pm today and there would be no doubt as to what was happening.

Research the 2003 6.4 quake just outside Puerto Plata. It was an experience still not forgotten.

[Cdn_Gringo]

A while back I posted on the force differences between various magnitudes of earthquakes. When you start throwing numbers and math around many lose interest pretty quickly.

Here is another way of looking at it.

For comparative purposes only, if a strong man was holding a stack of 4 cars over his head representing the 4.2 earthquake this afternoon ( I have no idea how to convert the actual force of a 4 into a specific number of cars so don't worry about it).

To this strong man's right, is another man holding a stack of cars equal to a magnitude 6 earthquake, that man would be holding a stack of 800 cars over his head. A 6 is roughly 200 times more forceful than a 4 (4 cars X 200 times more force = 800 cars). A 4 is 200 times more forceful than a 2. An 8 is 100 times more forceful than a 7 and 800 times more forceful than a magnitude 1 (as a generalization).

Remember this is not a doubling or tripling of force as in a 100% or 200% increase (double = 100% triple = 200% etc), it is and actual multiplication of the of the overall force as if you added 200 separate but equal earthquakes together to get a total.

If you are close enough, and concentrating you can feel a 3. You can definitely feel a 4 and you don't have to be paying particular attention before you notice it. You will absolutely feel a 5 and at about 5.3 or so, you might even be able to hear the rumble of the seismic waves. At 6, it becomes harder to maintain your balance but you probably won't fall over. You watch pictures fall off the walls, cupboard doors swing open and you should have good sized waves in your swimming pool. 7 and above, you are probably going to sit down before you fall down because standing will be very difficult. Furniture will move across the room, stuff falls out of cupboards, support structures crack and collapse due to shaking and not being able to support the weigh any longer, and lots of other not so nice things.

Shake duration is also significant. Obviously a force applied to objects for 10 seconds has less of an effect than that same force being applied for 30 seconds or a minute. Shaking can and has lasted for a very long time (relatively speaking). In some strong earthquakes continuous shaking for 2 or more minutes is not unheard of. All of the quakes that have occurred here in the DR in the last 4 years have all lasted less than 12 seconds and this is indicative of load shifting within the ground and fault line equalization - lots of little shifts to even the stress out over a greater distance. When this pressure equalization process is no longer effective, then after a period of stress buildup, there is a rupture and that produces a big one.

[Cdn_Gringo]

USGS info for this afternoons shaker:

Preliminary Report
Magnitude 4.4
Date-Time • 11 Nov 2018 18:02:51 UTC
• 11 Nov 2018 14:02:51 near epicenter
• 11 Nov 2018 14:02:51 standard time in your timezone
Location 19.762N 70.886W
Depth 10 km
Distances • 20 km (12 miles) WSW (258 degrees) of Puerto Plata, Puerto Plata, Dominican Republic
• 23 km (14 miles) N (356 degrees) of Villa Bison?, Santiago, Dominican Republic
• 23 km (14 miles) NNE (28 degrees) of Esperanza, Valverde, Dominican Republic
• 171 km (106 miles) NW (325 degrees) of SANTO DOMINGO, Dominican Republic
Location Uncertainty Horizontal: 2.3 km; Vertical 1.9 km
Parameters Nph = 39; Dmin = 96.0 km; Rmss = 1.34 seconds; Gp = 114°
Version =
Event ID us 1000hqlu

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[Matilda]

And another, only a 3.7 but felt it. 15.8 Km al NE de Guayubin, Montecristi at 4.23.

[Cdn_Gringo]

CNS is reporting a cluster of 4 this afternoon in the same area.

[Matilda]

Yup so is the Dominican earthquake site. Felt one and heard one.

2018-11-21 20:29:17 19.701, -71.330 20.5 4.0 7.8 Km al ENE de Guayubin, Montecristi.
2018-11-21 20:20:40 19.717, -71.215 12.1 3.5 19.7 Km al ENE de Guayubin, Montecristi.
2018-11-21 20:18:07 19.728, -71.223 15.1 3.6 19.3 Km al ENE de Guayubin, Montecristi.
2018-11-21 20:14:23 19.765, -71.285 23.0 3.7 15.8 Km al NE de Guayubin, Montecristi.

[Cdn_Gringo]

A lot of activity in that region in the last six weeks or so. No concrete conclusions can be drawn but something to keep simmering in the back of the mind in case it continues.

[Conchman]

Yup so is the Dominican earthquake site. Felt one and heard one.

2018-11-21 20:29:17 19.701, -71.330 20.5 4.0 7.8 Km al ENE de Guayubin, Montecristi.
2018-11-21 20:20:40 19.717, -71.215 12.1 3.5 19.7 Km al ENE de Guayubin, Montecristi.
2018-11-21 20:18:07 19.728, -71.223 15.1 3.6 19.3 Km al ENE de Guayubin, Montecristi.
2018-11-21 20:14:23 19.765, -71.285 23.0 3.7 15.8 Km al NE de Guayubin, Montecristi.

which Dominican website is this?

[Matilda]

which Dominican website is this?

The Dominican National Earthquake Centre

https://sismologico.uasd.edu.do/

It is very quick to update

Matilda

[Cdn_Gringo]

M4.7 Earthquake - Dominican Republic region
Preliminary Report
Magnitude 4.7
Date-Time • 7 Dec 2018 18:25:51 UTC
• 7 Dec 2018 13:25:51 near epicenter
• 7 Dec 2018 14:25:51 standard time in your timezone
Location 19.420N 68.004W
Depth 10 km
Distances • 101.9 km (63.2 mi) NNE of Punta Cana, Dominican Republic
• 115.9 km (71.9 mi) NE of Salvale�n de Higuey, Dominican Republic
• 130.8 km (81.1 mi) ENE of Santa Cruz de El Seibo, Dominican Republic
• 141.7 km (87.8 mi) NW of Aguadilla, Puerto Rico
• 142.1 km (88.1 mi) E of Saman�, Dominican Republic
Location Uncertainty Horizontal: 3.7 km; Vertical 31.6 km
Parameters Nph = 39; Dmin = 109.1 km; Rmss = 0.93 seconds; Gp = 217°
Version =
Event ID pr 20183410 ***This event has been revised.


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