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Terremotos


Carlos Dias
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Um terremoto com magnitude preliminar de M7.3 foi registrado há pouco na região da Papua Nova Guiné

Profundidade inicial estimada de 85 km.

 

PRELIMINARY EARTHQUAKE PARAMETERS
---------------------------------

  * MAGNITUDE      7.3
  * ORIGIN TIME    0250 UTC JUL 17 2020
  * COORDINATES    7.8 SOUTH  147.7 EAST
  * DEPTH          85 KM / 53 MILES
  * LOCATION       EASTERN NEW GUINEA REG  PAPUA NEW GUINEA

vMfp4vw.jpg

Edited by Tavares
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2 horas atrás, Sopron disse:

Tonga, bem próxima de Papua Nova Guiné registrou 6.1

tonga.jpg

Essa região que compreende o Mar de Salomão e as ilhas do Pacífico Sul é a a zona sísmica mais ativa do planeta. Quase 1/3 (29,1%) dos terremotos do mundo ocorrem nessa região que compreende as Zonas de Subducção da Nova Bretanha, Salomão, Nova Hébrides, Tonga e Kermadec.

A composição da crosta, com diversas micro-placas, a velocidade de deslocamento das placas (maiores nessa região) e o ângulo de subducção fazem com que essas zonas de atrito entre as placas libere energia antes de se acumular muito. Isso explica o grande número de terremotos e o baixo número de mega-terremotos. Só 15% dos terremotos de magnitude +M8 no último século aconteceram nessa região, o mais forte de "apenas" M8.2

Há uma lacuna sísmica na zona de subducção de Kermadec ao norte da Nova Zelândia que é a minha esperança de Mega-Terremoto no Pacífico Sudoeste.

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Mais uma vez o mapeamento das áreas de deslocamentos das placas usando dados de sismos antigos coincidindo com os locais onde grandes terremotos têm ocorrido.

Ainda que M7.8 não é energia suficiente pra preencher toda essa lacuna. Ainda há um grande terremoto potencial nessa região do Arco das Aleutas.

 

Edited by Tavares
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Terremoto moderado agora a pouco na região da Ilhas Sanduíche do Sul rs


 * MAGNITUDE         6.5
  * ORIGIN TIME       854 PM AST JUL 25 2020
  * COORDINATES       60.9 SOUTH  25.3 WEST
  * DEPTH             20 MILES / 33 KM
  * LOCATION          SOUTH SANDWICH ISLANDS REGION

 

Eu sou um pouco intrigado com essa microplaca da Sandwish do Sul.

OkfKIKi.jpg

Edited by Tavares
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21 horas atrás, Tavares disse:

Terremoto moderado agora a pouco na região da Ilhas Sanduíche do Sul rs


 * MAGNITUDE         6.5
  * ORIGIN TIME       854 PM AST JUL 25 2020
  * COORDINATES       60.9 SOUTH  25.3 WEST
  * DEPTH             20 MILES / 33 KM
  * LOCATION          SOUTH SANDWICH ISLANDS REGION

 

Eu sou um pouco intrigado com essa microplaca da Sandwish do Sul.

OkfKIKi.jpg

 

Poderia ocorrer um terremoto nessa região forte o suficiente para gerar tsunamis no litoral brasileiro?

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Em 25/07/2020 em 22:28, Tavares disse:

Terremoto moderado agora a pouco na região da Ilhas Sanduíche do Sul rs


 * MAGNITUDE         6.5
  * ORIGIN TIME       854 PM AST JUL 25 2020
  * COORDINATES       60.9 SOUTH  25.3 WEST
  * DEPTH             20 MILES / 33 KM
  * LOCATION          SOUTH SANDWICH ISLANDS REGION

 

Eu sou um pouco intrigado com essa microplaca da Sandwish do Sul.

OkfKIKi.jpg

 

Nunca se quer tinha reparado da existência dessas duas microplacas ao lado da Scotia, bem curioso e bizarro, sempre achei que fosse uma coisa só.

Placa_de_Sandwich.thumb.png.0c2225f7ba997fa50988bba3df0850a5.png

 

Em 26/07/2020 em 19:34, Renan disse:

 

Poderia ocorrer um terremoto nessa região forte o suficiente para gerar tsunamis no litoral brasileiro?

Acredito que é dali que vem o maior risco ao litoral argentino e brasileiro, devido a ser a única zona de subducção que existe aberta para o Atlântico Sul.

O @Felipe F poderia confirmar ou complementar pra gente.

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Um enxame sísmico está ocorrendo desde essa manhã na região de Salton Sea no sul da Califórnia cerca de 12 km ao sul do limite "conhecido" da falha de San Andreas. Cerca de 25 sismos de magnitude 2.5+ foram registrados até agora, o mais forte deles mediu M4.6. 

 

Os últimos grandes terremotos na Califórnia foram precedidos por enxames sísmicos, portanto o USGS publicou há pouco uma "previsão" de terremoto onde cita uma probabilidade de 19% de um terremoto de magnitude entre 5.5 e 6.9 e de 1% de um terremoto de magnitude 7+ ocorrer na próxima semana.

 

https://www.usgs.gov/center-news/earthquake-forecast-salton-sea-swarm-august-2020

 

Lembrando que há um ou dois anos essa região de Salton Sea sofreu um enxame sísmico com centenas de terremotos e nada aconteceu. 

Na torcida aqui. rs

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Um terremoto de magnitude preliminar de 5.9 foi registrado há pouco próximo à Dar Es Salaam capital da Tanzania.

 

Magnitude Mw 5.9
Region TANZANIA
Date time 2020-08-12 17:13:14.9 UTC
Location 7.37 S ; 39.72 E
Depth 2 km
Distances 78 km SE of Dar es Salaam, Tanzania, United Republic of / pop: 2,699,000 / local time: 20:13:14.9 2020-08-12
60 km N of Kilindoni, Tanzania, United Republic of / pop: 12,500 / local time: 20:13:14.9 2020-08-12

 

TgbCix8.jpg

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Matéria bem interessante sobre os terremotos "boomerang", que só recentemente foram comprovados cientificamente, em uma falha na Dorsal Mesoatlântica a cerca de mil km da costa do Nordeste Brasileiro.

 

São sismos raros que ocorrem sem sentido único, ou seja, percorrem a falha de um lado ao outro e voltam no sentido contrário, e viajam milhares de quilômetros em apenas alguns segundos. Terremotos desse tipo podem ser extremamente destrutivos e espalhar a onda sísmica a distâncias bem maiores.

Weird ‘boomerang’ earthquake detected under the Atlantic Ocean

image.thumb.png.a12fec08bf8d7d192cd0f43733062796.png

 

"It rushed eastward and upward, then did an about-face and boomeranged back along the upper section of the fault at incredible speeds‑so fast it caused the geologic version of a sonic boom.

 

The ferocity of shaking from an earthquake is usually focused in the direction the temblor is traveling. But a boomerang quake, or a “back-propagating rupture” in scientific terms, may spread the intense shaking across a wider zone. It remains uncertain how common boomerang earthquakes are—and how many travel at such great speeds. But the new study, published today in the journal Nature Geoscience, is a major step toward untangling the complex physics behind these events and understanding their potential hazards.

 

Further computer modeling suggested that the quake may have started deep underground rushing eastward until it neared the mid-ocean ridge. There, it turned back and raced through the upper section of the fault. This second leg of the temblor moved remarkably quickly, at so-called supershear speeds. The quake unzipped the surface at an estimated 11,000 miles per hour—fast enough to dart from New York to London in 18.5 minutes. This is so quick that the seismic waves pile up much like the Mach cone that forms from pressure waves as an airplane flies at supersonic speed. The concentrated cone of waves from a supershear quake can further amplify a temblor’s destructive power."

 

Reportagem completa: https://api.nationalgeographic.com/distribution/public/amp/science/2020/08/weird-boomerang-earthquake-detected-under-atlantic-ocean

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um terremoto de magnitude entre 6.5 e 6.8 nas Filipinas sendo reportado pelos serviços sismológicos internacionais

iAuU1nP.jpg

 

Dado do EMSC:


 
Magnitude Mw 6.7
Region SAMAR, PHILIPPINES
Date time 2020-08-18 00:03:52.4 UTC
Location 12.04 N ; 124.09 E
Depth 30 km
Distances 440 km SE of Manila, Philippines / pop: 10,445,000 / local time: 08:03:52.4 2020-08-18
127 km S of Legaspi, Philippines / pop: 180,000 / local time: 08:03:52.4 2020-08-18
10 km E of San Pedro, Philippines / pop: 2,400 / local time: 08:03:52.4 2020-08-18

 

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Um terremoto de magnitude preliminar de 6.8 foi registrado há pouco na região de Atacama, no Chile.

 

EMSC:

Magnitude  Mw 6.8
Region ATACAMA, CHILE
Date time 2020-09-01 04:09:25.9 UTC
Location 27.90 S ; 71.11 W
Depth 2 km
Distances 97 km SW of Copiapó, Chile / pop: 129,000 / local time: America/Santiago
83 km NW of Vallenar, Chile / pop: 44,800 / local time: America/Santiago
 

Source parameters not yet reviewed by a seismologist

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Em 30/08/2020 em 18:55, Tavares disse:

Um terremoto de magnitude 6.5 foi registrado há pouco no ponto mais próximo do Brasil da Dorsal Meso Atlântica.

O sismo ocorreu a 550 km de Fernando de Noronha.

7UGkFi3.png

Terremoto de magnitude 6.8 na mesma região agora a pouco. Não tenho como postar imagem agora.

O sensacionalismo vem. rs

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E lá vamos nós. Novamente o USGS divulga uma previsão de terremoto (dessa vez sem as porcentagens de chances de ocorrer)

https://www.usgs.gov/center-news/earthquake-forecast-westmorland-swarm-beginning-sept-30-2020

 

Citar

 

Earthquake Forecast for the Westmorland Swarm beginning Sept. 30, 2020

 
Release Date: SEPTEMBER 30, 2020

A swarm of earthquakes southeast of the Salton Sea, in the Brawley seismic zone, began on Sept. 30, 2020.

map showing earthquakes as circles near Salton Sea

Screenshot of Latest Earthquakes showing the Westmoreland Earthquake Swarm beginning Sep 30, 2020.

 

Earthquakes are shown as circles with the most recent in red.(Public domain.)

The largest earthquake that has occurred, as of this release, is a magnitude 4.9 at 5:31 PM PDT. This earthquake and the associated swarm are located in an area of diffuse seismic activity between the San Andreas fault in the north and the Imperial fault to the south.  This area has also seen swarms in the past –notably the 1981 Westmorland swarm, which included a M5.8 earthquake, and the 2012 Brawley swarm, which included a M5.4 earthquake.  Past swarms have remained active for 1 to 20 days, with an average duration of about a week.  The current swarm is occurring about 40 kilometers (25 miles) to the south of the swarm that occurred near Bombay Beach in August 2020.

In a typical week, there is approximately a 3 in 10,000 chance of a magnitude 7+ earthquake in the vicinity of this swarm. During this earthquake swarm, the probability of larger earthquakes in this region is significantly greater than usual.  Currently, the swarm is rapidly evolving, and we expect to update this forecast with more specific probability information as we collect more data.

The following three scenarios describe possibilities of what could happen from 30 September to 7 October.

Only one of these scenarios will occur within the next week. These scenarios include the possibility of earthquakes on and off the Imperial and San Andreas Faults.

1. Scenario One (Most likely):  Earthquakes continue, possibly including earthquakes up to magnitude 5.4.

The most likely scenario is that the rate of earthquakes in the swarm will decrease over the next 7 days. Some additional moderately sized earthquakes (M4.5 to 5.4) may occur, which could cause localized damage, particularly in weak structures.  Smaller magnitude earthquakes (M3.0+) may be felt by people close to the epicenters.

2. Scenario Two (Less likely): A larger earthquake (magnitude 5.5 to 6.9) could occur within the next 7 days.

A less likely scenario is a somewhat larger earthquake could occur (up to a M6.9). Earthquakes of this size could cause damage around the area close to the earthquakes that have already occurred and would be followed by aftershocks that would increase the number of smaller earthquakes per day. This scenario occurred in a previous swarm in the area – in 1981, when a swarm in this region included a magnitude 5.8 earthquake.

3. Scenario Three (Least Likely):  A much larger earthquake (magnitude 7 or higher) could occur within the next 7 days.

A much less likely scenario, compared with the previous two scenarios, is that the ongoing swarm could trigger an earthquake significantly larger than the M4.9 that occurred on the 30 September (i.e., M7.0 and above). While this is a very small probability, if such an earthquake were to occur, it would have serious impacts on communities nearby and would be followed by aftershocks that would increase the number of smaller earthquakes per day.

 

 

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