O Sismo de Messina, que arrasou o sul de Itália e a Sicília, foi há 115 anos...

Date	December 28, 1908 5:20 am
Magnitude	7.1 Mw
Epicenter	38.15°N 15.683°E
Areas affected	Sicily & Calabria, Italy
Tsunami	Yes
Casualties	100.000 to 200.000

The 1908 Messina earthquake (also known as the 1908 Messina and Reggio earthquake) and tsunami took about 123.000 lives on December 28, 1908, in Sicily and Calabria, southern Italy. The major cities of Messina and Reggio Calabria were almost completely destroyed.

   

Messina

 

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Um terramoto arrasou a cidade de Bam há vinte anos

   

O Sismo de Bam de 2003 foi um sismo ocorrido em 26 de dezembro de 2003 na cidade de Bam (Irão) que destruiu a maior parte da cidade e causou dezenas de milhares de mortos.

A fortaleza da cidade, Património da Humanidade, foi declarada "em perigo" pela UNESCO.

Segundo as autoridades iranianas, o sismo causou entre 40.000 e 50.000 mortos, mas as estimativas mais rigorosas contam entre 25.000 e 30.000.

  

Fotografias do antes e depois da parte histórica de Bam

   

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A estranha crise sísmica de New Madrid começou há 212 anos

The Great Earthquake at New Madrid, a 19th-century woodcut from Devens' Our First Century (1877)

      
The 1811–1812 New Madrid earthquakes were an intense intraplate earthquake series beginning with an initial earthquake of moment magnitude (7,5 -7,9) on December 16, 1811 followed by a moment magnitude 7,4 aftershock on the same day. They remain the most powerful earthquakes to hit the contiguous United States east of the Rocky Mountains in recorded history. They, as well as the seismic zone of their occurrence, were named for the Mississippi River town of New Madrid, then part of the Louisiana Territory, now within Missouri.

There are estimates that the earthquakes were felt strongly over roughly 130,000 square kilometers, and moderately across nearly 3 million square kilometers. The 1906 San Francisco earthquake, by comparison, was felt moderately over roughly 16,000 km².

  

New Madrid fault and earthquake-prone region considered at high risk today

  

 The three earthquakes and their major aftershocks

• December 16, 1811, 08.15 UTC (2:15 a.m.); (M 7,5 -7,9) epicenter in northeast Arkansas. It caused only slight damage to manmade structures, mainly because of the sparse population in the epicentral area. The future location of Memphis, Tennessee, experienced level IX shaking on the Mercalli intensity scale. A seismic seiche propagated upriver, and Little Prairie (a village that was on the site of the former Fort San Fernando, near the site of present-day Caruthersville, Missouri) was heavily damaged by soil liquefaction.
• December 16, 1811 (aftershock), 14.15 UTC (8:15 a.m.); (M 7,4) epicenter in northeast Arkansas. This shock followed the first earthquake by five hours and was similar in intensity.
• January 23, 1812, 15.00 UTC (9:00 a.m.); (M 7,3 -7,6) epicenter in the Missouri Bootheel. The meizoseismal area was characterized by general ground warping, ejections, fissuring, severe landslides, and caving of stream banks. Johnson and Schweig attributed this earthquake to a rupture on the New Madrid North Fault. This may have placed strain on the Reelfoot Fault.
• February 7, 1812, 09.45 UTC (3:45 a.m.); (M 7,5 -8,0) epicenter near New Madrid, Missouri. New Madrid was destroyed. In St. Louis, Missouri, many houses were severely damaged, and their chimneys were toppled. This shock was definitively attributed to the Reelfoot Fault by Johnston and Schweig. Uplift along a segment of this reverse fault created temporary waterfalls on the Mississippi at Kentucky Bend, created waves that propagated upstream, and caused the formation of Reelfoot Lake by obstructing streams in what is now Lake County, Tennessee.

Susan Hough, a seismologist of the United States Geological Survey (USGS), has estimated the earthquakes' magnitudes as around magnitude 7.

There were many more aftershocks including one magnitude 7 aftershock to December 16, 1811 earthquake which occurred on December 17, 1811 at 0600 UTC (12:00 a.m.) and one magnitude 7 aftershock to February 7, 1812 earthquake which occurred on the same day at 0440 UTC (10:40 p.m.).

  
Eyewitness accounts

John Bradbury, a Fellow of the Linnean Society, was on the Mississippi on the night of December 15, 1811, and describes the tremors in great detail in his Travels in the Interior of America in the Years 1809, 1810 and 1811, published in 1817.

After supper, we went to sleep as usual: about ten o'clock, and in the night I was awakened by the most tremendous noise, accompanied by an agitation of the boat so violent, that it appeared in danger of upsetting ... I could distinctly see the river as if agitated by a storm; and although the noise was inconceivably loud and terrific, I could distinctly hear the crash of falling trees, and the screaming of the wild fowl on the river, but found that the boat was still safe at her moorings.
By the time we could get to our fire, which was on a large flag in the stern of the boat, the shock had ceased; but immediately the perpendicular banks, both above and below us, began to fall into the river in such vast masses, as nearly to sink our boat by the swell they occasioned ... At day-light we had counted twenty-seven shocks.

Eliza Bryan in New Madrid, Territory of Missouri, wrote the following eyewitness account in March 1812.

On the 16th of December, 1811, about two o'clock, a.m., we were visited by a violent shock of an earthquake, accompanied by a very awful noise resembling loud but distant thunder, but more hoarse and vibrating, which was followed in a few minutes by the complete saturation of the atmosphere, with sulphurious vapor, causing total darkness. The screams of the affrighted inhabitants running to and fro, not knowing where to go, or what to do—the cries of the fowls and beasts of every species—the cracking of trees falling, and the roaring of the Mississippi— the current of which was retrograde for a few minutes, owing as is supposed, to an irruption in its bed— formed a scene truly horrible.

John Reynolds (February 26, 1788 – May 8, 1865) who was the 4th governor of Illinois, among other political posts, mentions the earthquake in his biography My Own Times: Embracing Also the History of My Life (1855):

On the night of 16th November [sic], 1811, an earthquake occurred, that produced great consternation amongst the people. The centre of the violence was in New Madrid, Missouri, but the whole valley of the Mississippi was violently agitated. Our family all were sleeping in a log cabin, and my father leaped out of bed crying aloud "the Indians are on the house" ... We laughed at the mistake of my father, but soon found out it was worse than the Indians. Not one in the family knew at the time that it was an earthquake. The next morning another shock made us acquainted with it, so we decided it was an earthquake. The cattle came running home bellowing with fear, and all animals were terribly alarmed on the occasion. Our house cracked and quivered, so we were fearful it would fall to the ground. In the American Bottom many chimneys were thrown down, and the church bell in Cahokia sounded by the agitation of the building. It is said the shock of an earthquake was felt in Kaskaskia in 1804, but I did not perceive it. The shocks continued for years in Illinois, and some have experienced it this year, 1855.

The Shaker diarist Samuel Swan McClelland described the effects of the earthquake on the Shaker settlement at West Union (Busro), Indiana, where the earthquakes contributed to the temporary abandonment of the westernmost Shaker community.

     

Reelfoot Rift

    

Geologic setting

The underlying cause of the earthquakes is not well understood, but modern faulting seems to be related to an ancient geologic feature buried under the Mississippi River alluvial plain, known as the Reelfoot Rift. The New Madrid Seismic Zone (NMSZ) is made up of reactivated faults that formed when what is now North America began to split or rift apart during the breakup of the supercontinent Rodinia in the Neoproterozoic Era (about 750 million years ago). Faults were created along the rift and igneous rocks formed from magma that was being pushed towards the surface. The resulting rift system failed but has remained as an aulacogen (a scar or zone of weakness) deep underground.

In recent decades minor earthquakes have continued. The epicenters of over 4,000 earthquakes can be identified from seismic measurements taken since 1974. It can be seen that they originate from the seismic activity of the Reelfoot Rift. The zone which is colored in red on the map is called the New Madrid Seismic Zone. New forecasts estimate a 7 to 10 percent chance, in the next 50 years, of a repeat of a major earthquake like those that occurred in 1811–1812, which likely had magnitudes of between 7,6 and 8,0. There is a 25 to 40 percent chance, in a 50-year time span, of a magnitude 6,0 or greater earthquake.

In a report filed in November 2008, the U.S. Federal Emergency Management Agency warned that a serious earthquake in the New Madrid Seismic Zone could result in "the highest economic losses due to a natural disaster in the United States," further predicting "widespread and catastrophic" damage across Alabama, Arkansas, Illinois, Indiana, Kentucky, Mississippi, Missouri, and particularly Tennessee, where a 7,7 magnitude quake or greater would cause damage to tens of thousands of structures affecting water distribution, transportation systems, and other vital infrastructure.

    

4000 earthquake reports since 1974

      

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Há 71 anos ocorreu um dos mais fortes sismos do século XX, na península de Kamchatka, Rússia

  

The main earthquake struck at 16:58 GMT (04:58 local time) on November 4, 1952. Initially assigned a magnitude of 8.2, the quake was revised to 9.0 M_w in later years. A large tsunami resulted, causing destruction and loss of life around the Kamchatka peninsula and the Kuril Islands. Hawaii was also struck, with estimated damages of up to US$1 million and livestock losses, but no human casualties were recorded. Japan reported no casualties or damage. The tsunami reached as far as Alaska, Chile, and New Zealand.

The hypocentre was located at 52.75°N 159.5°E, at a depth of 30 km. The length of the subduction zone fracture was 600 km. Aftershocks were recorded in an area of approximately 247,000 km², at depths of between 40 and 60 km. A recent analysis of the tsunami runup distribution based on historical and geological records give some indication as to the slip distribution of the rupture.

 

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View of the Severo-Kurilsk port. In 1952 a whole settlement was located there. The modern town was rebuilt in another place

1952 Severo-Kurilsk Tsunami was a major tsunami that hit Severo-Kurilsk, Kuril Islands, Sakhalin Oblast, Russian SFSR, USSR, which occurred on 5 November 1952 at about 5 a.m. It led to the destruction of many settlements in Sakhalin Oblast and Kamchatka Oblast, while the main impact struck the town of Severo-Kurilsk. The tsunami was generated by a major earthquake in the Pacific Ocean, 130 km from the shore of Kamchatka, with an estimated magnitude of 9.0. There were three waves about 15-18 m high. After the earthquake the majority of the Severo-Kurilsk citizens fled to the surrounding hills, where they escaped the first wave. However, most of them returned to the town and were killed by the second wave. The third wave was minor. According to the authorities, out of a population of 6,000 people, 2,336 died.
The remaining survivors were evacuated to continental Russia. The settlement was then rebuilt in another location.

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NOTA: embora provocando poucos mortos, dada a sua magnitude, este sismo é considerado atualmente o 12º com mais elevada magnitude, segundo a Wikipédia:

 

 

Rank	Date	Location	Event	Magnitude
1	May 22, 1960	Valdivia, Chile	1960 Valdivia earthquake	9.4–9.6
2	June 11, 1585	Pacific Ocean, Aleutian Islands (now Alaska, United States)	1585 Aleutian Islands earthquake	9.25 (est.)
3	July 8, 1730	Valparaiso, Chile (then part of the Spanish Empire)	1730 Valparaíso earthquake	9.1–9.3 (est.)
4	March 27, 1964	Prince William Sound, Alaska, United States	1964 Alaska earthquake	9.2
5	December 26, 2004	Indian Ocean, Sumatra, Indonesia	2004 Indian Ocean earthquake	9.1–9.3
6	October 17, 1737	Kamchatka Peninsula, Russia	1737 Kamchatka earthquake	9.0–9.3 (est.)
7	November 17, 1837	Valdivia, Chile	1837 Valdivia earthquake	8.8–9.5 (est.)
8	March 11, 2011	Pacific Ocean, Tōhoku region, Japan	2011 Tōhoku earthquake	9.1
9	October 28, 1707	Pacific Ocean, Shikoku region, Japan	1707 Hōei earthquake	8.7–9.3 (est.)
10	November 25, 1833	Sumatra, Indonesia (then part of the Dutch East Indies)	1833 Sumatra earthquake	8.8–9.2 (est.)
11	May 17, 1841	Kamchatka, Russian Empire	1841 Kamchatka earthquake	9.0 (est.)
12	November 4, 1952	Kamchatka, Russian SFSR, Soviet Union	1952 Severo-Kurilsk earthquake	9.0

 

O sismo de Loma Prieta foi há trinta e quatro anos...

  

O Sismo de Loma Prieta de 1989 ocorreu na região da área da baía de São Francisco, na Califórnia, Estados Unidos, no dia 17 de outubro de 1989, às 17.04, hora local (00.04 UTC no dia 18), e teve magnitude de 6,9 na escala de magnitude de momento (Mw). O epicentro foi a 16 km a nordeste de Santa Cruz, numa secção na Falha de Santo André na montanha de Loma Prieta (que deu o nome ao sismo), localizada ao longo das Montanhas de Santa Cruz. Teve duração de 8 a 15 segundos e o hipocentro foi a uma profundidade de 19 km. Causou a morte de 63 pessoas e outras 3.757 ficaram feridas. O prejuízo total foi de cerca de 5,6 a 6 mil milhões de dólares.

O terramoto ficou mais conhecido por ser o primeiro sismo da era moderna com epicentro nos Estados Unidos a ser transmitido ao vivo, em rede nacional, por uma emissora de televisão no país, a American Broadcasting Company (ABC), devido ao jogo n.º 3 da World Series da Major League Baseball de 1989 que estava para ser iniciado no Candlestick Park, e por coincidência, tinha como finalistas as duas equipas da área da baía de São Francisco (região atingida pelo tremor de terra), os San Francisco Giants e os Oakland Athletics. 

 

  

 

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Há 26 anos, um terramoto, com forte abalo premonitório e muitas réplicas, matou onze pessoas em Itália

Afresco destruído, de Cimbabue, na Basílica de São Francisco

1997 Umbria and Marche earthquake

Date	11:40:26, September 26, 1997 (UTC)
Magnitude	6.1 Mw
Depth	10 km (6.2 mi)
Epicenter	43.084°N 12.812°E
Countries or regions	Italy (Umbria, Marche)
Casualties	11 dead 100 injured

 

The 1997 Umbria and Marche earthquake consisted of two earthquakes that occurred in the regions of Umbria and Marche, central Italy, in quick succession on the morning of September 26, 1997.

The first shock occurred at 2:33 am CEST (0:33 UTC), rated 5.5 on the Richter scale, and the second – the main shock – occurred at 11:40 am CEST (9:40 UTC), rated 6.1 on the Richter scale. Their epicentre was in Annifo.

There were several thousands of foreshocks and aftershocks from May 1997 to April 1998, more than thirty of which had a Richter magnitude more than 3.5. 11 people are known to have died following the shocks of September 26, 1997.
   

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Notícia que a resposta a uma pergunta que muitos alunos fazem sobre o núcleo terrestre...

Por que o núcleo da Terra é mais quente que a superfície do Sol, mas é sólido?

  

   

Apesar de ser mais quente do que a superfície do sol, o núcleo interno da Terra é sólido devido à imensa pressão exercida pelas sucessivas camadas superiores no interior do planeta.

O núcleo da Terra, uma esfera metálica com aproximadamente 2.400 quilómetros de largura, está sujeito a pressões de cerca de 350 gigapascais, equivalentes a mais de três milhões de vezes a pressão atmosférica ao nível do mar.

Esta colossal pressão é suficiente para converter uma mistura de ferro, níquel e outros elementos de líquido para sólido.

Os cientistas descobriram que a temperatura na superfície do núcleo interno da Terra é de 5.700 a 6.200 ºC.

O facto de o núcleo interno da Terra ser sólido pode parecer contraditório, uma vez que os materiais, a altas temperaturas, geralmente passam de estado sólido para líquido, e de líquido para gasoso.

No entanto, da mesma forma como a água ferve a temperaturas mais baixas em altitudes mais elevadas devido à redução da pressão do ar, a pressão aumentada pode elevar a temperatura à qual uma substância funde, explica o IFLS.

Os cientistas determinam a temperatura na fronteira do núcleo interno sólido e do núcleo externo líquido calculando a pressão nesse ponto e estimando quão quentes os metais do núcleo podem ser, mantendo-se ainda sólidos.

   

  

Devido à falta de medições diretas, estas estimativas variam, mas uma desvio de 10% é considerado insignificante ao lidar com condições tão extremas.

Além disso, especula-se que o núcleo interno está a expandir-se lentamente, porque o núcleo está gradualmente a arrefecer à medida que a concentração de elementos radioativos que o aquecem diminui, fazendo com que partes do núcleo externo solidifiquem.

No entanto, não é absolutamente certo que o núcleo interno seja verdadeiramente sólido, devido à semelhança na forma como as vibrações viajam através de sólidos e líquidos extremamente viscosos.

Alguns cientistas avançam a hipótese de que, se o núcleo interno for de facto um líquido altamente viscoso.

Essa viscosidade poderia contribuir para o campo magnético do planeta e explicar por que motivo as ondas sísmicas demoram mais tempo a viajar, pelo interior da Terra, nas regiões equatoriais do que nas regiões polares.

 

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Houve quatro sismos sentidos em Portugal continental no dia de hoje (post atualizado)

Houve três sismos, dois no Algarve e um no Alentejo, sentidos pela população local, só no dia de hoje (5 de setembro de 2023)...

Aqui fica um mapa do IPMA com o mais forte desses sismos (intensidade IV):

 

Para quem sentiu algum dos sismos, uma sugestão - vão ao seguinte link e respondam ao inquérito on line do IPMA:

https://www.ipma.pt/pt/geofisica/informe/

 

ADENDA: houve mais um sismo sentido em Portugal continental no dia de hoje, que nos fez alterar o título da publicação - desta vez o sismo foi perto de Castro Daire e São Pedro do Sul...! É provavelmente um record nacional - quase que chegamos aos Açores.

Houve um inacreditável terramoto no Japão há um século...

  

Marunouchi (commercial district of Tokyo) in flames

   

The Great Kantō earthquake struck the Kantō plain on the Japanese main island of Honshū at 11:58:44 am JST (2:58:44 UTC) on Saturday, September 1, 1923. Varied accounts indicate the duration of the earthquake was between four and 10 minutes. This was the deadliest earthquake in Japanese history, and at the time was the most powerful earthquake ever recorded in the region. The 2011 Tōhoku earthquake later surpassed that record, at magnitude 9.0.

The earthquake had a magnitude of 7.9 on the Moment magnitude scale (M_w), with its focus deep beneath Izu Ōshima Island in the Sagami Bay. The cause was rupture of part of the convergent boundary where the Philippine Sea Plate is subducting beneath the Okhotsk Plate along the line of the Sagami Trough.

This earthquake devastated Tokyo, the port city of Yokohama, and the surrounding prefectures of Chiba, Kanagawa, and Shizuoka, and caused widespread damage throughout the Kantō region. The power was so great in Kamakura, over 60 km (37 mi) from the epicenter, it moved the Great Buddha statue, which weighs about 93 short tons (84,000 kg), almost two feet.

Estimated casualties totaled about 142,800 deaths, including about 40,000 who went missing and were presumed dead. The damage from this natural disaster was the greatest sustained by prewar Japan. In 1960, the government of Japan declared September 1, the anniversary of the quake, as an annual "Disaster Prevention Day".

According to the Japanese construction company Kajima Kobori Research's conclusive report of September 2004, 105,385 deaths were confirmed in the 1923 quake.

  

Damage and deaths

Because the earthquake struck at lunchtime when many people were cooking meals over fire, many people died as a result of the many large fires that broke out. Some fires developed into firestorms that swept across cities. Many people died when their feet became stuck in melting tarmac. The single greatest loss of life was caused by a firestorm-induced fire whirl that engulfed open space at the Rikugun Honjo Hifukusho (formerly the Army Clothing Depot) in downtown Tokyo, where about 38,000 people were incinerated after taking shelter there following the earthquake. The earthquake broke water mains all over the city, and putting out the fires took nearly two full days until late in the morning of September 3. An estimated 140,000 people were killed and 447,000 houses were destroyed by the fire alone.
A strong typhoon struck Tokyo Bay at about the same time as the earthquake. Some scientists, including C.F. Brooks of the United States Weather Bureau, suggested the opposing energy exerted by a sudden decrease of atmospheric pressure coupled with a sudden increase of sea pressure by a storm surge on an already-stressed earthquake fault, known as the Sagami Trough, may have triggered the earthquake. Winds from the typhoon caused fires off the coast of Noto Peninsula in Ishikawa Prefecture to spread rapidly.
The Emperor and Empress were staying at Nikko when the earthquake struck Tokyo, and were never in any danger.

Many homes were buried or swept away by landslides in the mountainous and hilly coastal areas in western Kanagawa Prefecture, killing about 800 people. A collapsing mountainside in the village of Nebukawa, west of Odawara, pushed the entire village and a passenger train carrying over 100 passengers, along with the railway station, into the sea.
A tsunami with waves up to 10 m (33 ft) high struck the coast of Sagami Bay, Boso Peninsula, Izu Islands, and the east coast of Izu Peninsula within minutes. The tsunami killed many, including about 100 people along Yui-ga-hama Beach in Kamakura and an estimated 50 people on the Enoshima causeway. Over 570,000 homes were destroyed, leaving an estimated 1.9 million homeless. Evacuees were transported by ship from Kanto to as far as Kobe in Kansai. The damage is estimated to have exceeded USD$1 billion (or about $13,475 billion today). There were 57 aftershocks.
Altogether, the earthquake and typhoon killed an estimated 99,300 people, and another 43,500 went missing.

   

Postquake massacre of ethnic minorities and political opponents

The Home Ministry declared martial law, and ordered all sectional police chiefs to make maintenance of order and security a top priority. A rumor spread was that Koreans were taking advantage of the disaster, committing arson and robbery, and were in possession of bombs. Anti-Korean sentiment was heightened by fear of the Korean independence movement, partisans of which were responsible for assassinations of top Japanese officials and other terrorist activity. In the confusion after the quake, mass murder of Koreans by mobs occurred in urban Tokyo and Yokohama, fueled by rumors of rebellion and sabotage. The government reported 2613 Koreans were killed by mobs in Tokyo and Yokohama in the first week of September. Independent reports said the number killed was far higher. Some newspapers reported the rumors as fact, including the allegation that Koreans were poisoning wells. The numerous fires and cloudy well water, a little-known effect of a large quake, all seemed to confirm the rumors of the panic-stricken survivors who were living amidst the rubble. Vigilante groups set up roadblocks in cities, and tested residents with a shibboleth for supposedly Korean-accented Japanese: deporting, beating, or killing those who failed. Army and police personnel colluded in the vigilante killings in some areas. Of the 3,000 Koreans taken into custody at the Army Cavalry Regiment base in Narashino, Chiba Prefecture, 10% were killed at the base, or after being released into nearby villages. Moreover, anyone mistakenly identified as Korean, such as Chinese, Okinawans, and Japanese speakers of some regional dialects, suffered the same fate. About 700 Chinese, mostly from Wenzhou, were killed. A monument commemorating this was built in 1993 in Wenzhou.

In response, the government called upon the Japanese Army and the police to detain Koreans to defuse the situation; 23.715 Koreans were detained across Japan, 12.000 in Tokyo alone. The chief of police of Tsurumi (or Kawasaki by some accounts) is reported to have publicly drunk the well water to disprove the rumor that Koreans had been poisoning wells. In some towns, even police stations into which Korean people had escaped were attacked by mobs, whereas in other neighbourhoods, residents took steps to protect them. The Army distributed flyers denying the rumor and warning civilians against attacking Koreans, but in many cases vigilante activity only ceased as a result of Army operations against it. As Allen notes, the Japanese colonial occupation of Korea provided the backdrop to this extreme example of the explosion of racial prejudice into violence, based on a history of antagonism. To be a Korean in 1923 Japan was to be not only despised, but also threatened and possibly killed.
Amidst the mob violence against Koreans in the Kantō Region, regional police and the Imperial Army used the pretext of civil unrest to liquidate political dissidents. Socialists such as Hirasawa Keishichi, anarchists such as Sakae Osugi and Noe Ito, and the Chinese communal leader, Ou Kiten, were abducted and killed by local police and Imperial Army, who claimed the radicals intended to use the crisis as an opportunity to overthrow the Japanese government.
The importance of obtaining and providing accurate information following natural disasters has been emphasized in Japan ever since. Earthquake preparation literature in modern Japan almost always directs citizens to carry a portable radio and use it to listen to reliable information, and not to be misled by rumors in the event of a large earthquake.
   
Aftermath
Following the devastation of the earthquake, some in the government considered the possibility of moving the capital elsewhere. Proposed sites for the new capital were even discussed.
Japanese commentators interpreted the disaster as an act of divine (Kami) punishment to admonish the Japanese people for their self-centered, immoral, and extravagant lifestyles. In the long run, the response to the disaster was a strong sense that Japan had been given an unparalleled opportunity to rebuild the city, and to rebuild Japanese values. In reconstructing the city, the nation, and the Japanese people, the earthquake fostered a culture of catastrophe and reconstruction that amplified discourses of moral degeneracy and national renovation in interwar Japan.
After the earthquake, Gotō Shimpei organized a reconstruction plan of Tokyo with modern networks of roads, trains, and public services. Parks were placed all over Tokyo as refuge spots, and public buildings were constructed with stricter standards than private buildings to accommodate refugees. However, the outbreak of World War II and subsequent destruction severely limited resources.
Frank Lloyd Wright received credit for designing the Imperial Hotel, Tokyo, to withstand the quake, although in fact the building was damaged by the shock. The destruction of the US embassy caused Ambassador Cyrus Woods to relocate the embassy to the hotel. Wright's structure withstood the anticipated earthquake stresses, and the hotel remained in use until 1968.
The unfinished battlecruiser Amagi was in drydock being converted into an aircraft carrier in Yokosuka in compliance with the Washington Naval Treaty of 1922. However, the earthquake damaged the Amagi beyond repair, leading it to be scrapped, and the unfinished fast battleship Kaga was converted into an aircraft carrier in its place.
In contrast to London, where typhoid fever had been steadily declining since the 1870s, the rate in Tokyo remained high, more so in the upper-class residential northern and western districts than in the densely populated working-class eastern district. An explanation is the decline of waste disposal, which became particularly serious in the northern and western districts when traditional methods of waste disposal collapsed due to urbanization. The 1923 earthquake led to record-high morbidity due to unsanitary conditions following the earthquake, and it prompted the establishment of antityphoid measures and the building of urban infrastructure.

   

Memory

Beginning in 1960, every September 1 is designated as Disaster Prevention Day to commemorate the earthquake and remind people of the importance of preparation, as September and October are the middle of the typhoon season. Schools and public and private organizations host disaster drills. Tokyo is located near a fault zone beneath the Izu peninsula which, on average, causes a major earthquake about once every 70 years, and is also located near the Sagami Trough, a large subduction zone that threatens to create a massive earthquake that, in the darkest case, would kill millions in the Kanto Region. Every year on this date, schools across Japan take a moment of silence at the precise time the earthquake hit in memory of the lives lost.

Some discreet memorials are located in Yokoamicho Park in Sumida Ward, at the site of the open space in which an estimated 38,000 people were killed by a single firestorm. The park houses a Buddhist-style memorial hall/museum, a memorial bell donated by Taiwanese Buddhists, a memorial to the victims of World War II Tokyo air raids, and a memorial to the Korean victims of the vigilante killings.

       

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Ontem a terra mexeu bastante em Portugal...

 É dia de sismos em Portugal. Três foram sentidos pela população

 

Quatro sismos registados em poucas horas. Um deles decorreu de madrugada e foi sentido em Peniche.

 

Herbert Hall Turner, astrónomo e sismólogo, nasceu há 162 anos

Herbert Hall Turner (Leeds, 13 August 1861  – Stockholm, 20 August 1930) was a British astronomer and seismologist.

Herbert Hall Turner was educated at Clifton College and Trinity College, Cambridge. In 1884 he accepted the post of Chief Assistant at Greenwich Observatory and stayed there for nine years. In 1893 he became Savilian Professor of Astronomy and Director of the Observatory at Oxford University, a post he held for 37 years until his sudden death in 1930.

He was one of the observers in the Eclipse Expeditions of 1886 and 1887. In seismology, he is credited with the discovery of deep focus earthquakes. He is also credited with coining the word parsec.

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Notícia interessante sobre tectónica e sismologia portuguesas...

Placas tectónicas a “escamar” podem explicar mistério de terramotos em Portugal

 

Epicentro do terramoto de 1969

 

Investigadores suspeitam que o “descasque” de uma placa tectónica possa ter estado na origem dos terramotos de 1755 e 1969 que fustigaram Lisboa.

Sempre que um terramoto de magnitudes mais significativas acontece (como o que fustigou a Turquia e a Síria, no início de fevereiro), a possibilidade de um evento semelhante acontecer em Portugal é abordada pelos meios de comunicação.

Os especialistas são unânimes nos contributos, devido à sua localização, o país (sobretudo a zona sul) está particularmente exposto a um sismo de grandes dimensões. Já aconteceu no passado, não há motivo para acreditar que não se vai repetir.

Os especialistas têm estado atentos, pelo que já notaram um fenómeno estranho que está a acontecer ao largo da costa portuguesa, mas nas profundezas do oceano Atlântico. Uma placa tectónica está a descascar, criando uma nova “zona de subducção” que um dia pode vir a tornar-se um foco de atividade sísmica e vulcânica.

A descoberta representa a primeira do seu tipo, pelo menos nesta fase de “descasque”, e está a ser apontada como causa provável para o terramoto de 1755 e para outro de dimensões mais pequenas que se registou em 1969.

Apesar das condições favoráveis, os cientistas nunca conseguiram designar uma causa clara para os dois eventos, lembra João Duarte, geólogo da Universidade de Lisboa, citado pela NBC News.

A crosta terrestre é constituída por várias placas tectónicas, ou seja, placas rochosas de forma irregular que chocam, sobem ou deslizam umas por baixo das outras à medida que se movimentam lenta mas continuamente.

Os sismos, assim como as erupções vulcânicas, tendem a agrupar-se nas zonas de subducção, as quais ocorrem ao longo dos limites entre as placas quando uma é empurrada para baixo de outra.

O terramoto de Lisboa, sentido a 1 de novembro de 1755, atingiu grande parte da cidade, provocou um tsunami e causou até 100.000 mortes.

Na altura, os sismógrafos não existiam, mas os cientistas estimam que foi um sismo de magnitude 8,5 a 8,7. Mais de dois séculos depois, a 28 de fevereiro de 1969, um terramoto de magnitude 7,8 atingiu a mesma área.

Para compreender o que poderia ter estado na origem dos sismos, João Duarte e os seus colegas analisaram dados sísmicos recolhidos em 2007 e 2008 a partir de ferramentas colocados no fundo do mar, os quais foram cruzados com dados de outros dois estudos.

Essas pesquisas detetaram uma estranha região densa a 240 quilómetros abaixo do epicentro do sismo de 1969.

O investigador vê nos dados a prova de que é a prova de que a água do mar está lentamente a infiltrar-se na placa tectónica através de uma série de fissuras, enfraquecendo a sua estrutura geral e fazendo com que a parte inferior da placa se afaste do topo.

O processo pode ter começado há cerca de 10 milhões de anos, apontou, acrescentando que a modelagem por computador confirmou o processo como uma possibilidade provável.

“Por vezes, penso no fenómeno como uma zona de subducção embrionária“, disse Duarte. “Ainda não está totalmente madura, mas as condições estão todas lá”.

 

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O Grande Sismo de Tangshan foi há 47 anos....

    

O Sismo de Tangshan de 28 de julho de 1976 foi o mais grave terramoto que afligiu o mundo moderno no que diz respeito a vidas perdidas, tendo sido registado uma magnitude de  7,5 na escala de Richter. Atingiu a cidade da Tangshan, na República Popular da China às 03.52 horas da manhã, matando oficialmente 242.419 pessoas, de acordo com os dados divulgados, mas, segundo algumas fontes, esse número está estimado como sendo três vezes maior.

Muitas das pessoas que sobreviveram ao terramoto ficaram presas sob os edifícios que caíram, não resistindo à réplica de magnitude 7,1 quinze horas depois do terramoto principal, seguidos de muitas réplicas de 5.0 e 5.5. Muitas pessoas afirmaram ter visto luzes estranhas na noite anterior ao terramoto, que ficaram conhecidas como as luzes do terramoto.

78% dos edifícios industriais, 93% dos edifícios residenciais, 80% das estações de bombeamento de água e 14 linhas de esgoto ou foram completamente destruídos ou ficaram bastante danificados. As ondas sísmicas libertadas para longe e alguns edifícios localizados tão longe como Pequim, a 140 km do epicentro, ficaram danificados.

O Terramoto de Tangshan é o segundo mais mortífero que foi registado, ficando após o sismo de 1556 de Shanxi, também na China, onde foram registados 830.000 mortos; contudo, documentos deste período são muito difíceis de encontrar.

     

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The Tangshan Earthquake, also known as the Great Tangshan Earthquake, was a natural disaster that occurred on Wednesday, July 28, 1976. It is believed to be the largest earthquake of the 20th century by death toll. The epicenter of the earthquake was near Tangshan in Hebei, People's Republic of China, an industrial city with approximately one million inhabitants. The number of deaths initially reported by the Chinese government was 655.000, but this number has since been stated to be around 240.000 to 255.000. Another report indicates that the actual death toll was much higher, at approximately 650.000, and explains that the lower estimates are limited to Tangshan and exclude fatalities in the densely populated surrounding areas.

A further 164.000 people were recorded as being severely injured. The earthquake occurred between a series of political events involving the Communist Party of China, ultimately leading to the expulsion of the ruling Gang of Four by Mao's chosen successor, Hua Guofeng. In traditional Chinese thought, natural disasters are seen as a precursor of dynastic change.

The earthquake hit in the early morning, at 03.42.53,8 local time (1976 July 27 19.42.53,8 UTC), and lasted 14 to 16 seconds. Chinese government official sources state a magnitude of 7,8 on the Richter magnitude scale, though some sources listed it as high as 8,2. It was followed by a major 7,1 magnitude aftershock some 16 hours later, increasing the death toll to over 255.000. The earthquake was generated by the 25-mile long Tangshan Fault, which runs near the city and ruptured due to tectonic forces caused by the Amurian Plate sliding past the Eurasian Plate.

     

Controversial statistics

Until fairly recently, China's political environment has made it difficult to properly gauge the extent of natural disasters. Successive governments have placed more importance on the appearance of harmony rather than accurate information on damages. The Tangshan Earthquake came at a rather politically sensitive time during the late stages of the Cultural Revolution, making accurate statistics especially difficult to find. The Tangshan earthquake killed 242.000 people according to official figures, though some sources estimate a death toll up to three times higher. This would make it the deadliest earthquake in modern times, and the second or third deadliest in recorded history. It is worth noting that the population of Tangshan at the time the quake struck was estimated to be around 1.6 million and that most of Tangshan's city proper was flattened.

Many experts believe the Chinese government has never released an accurate death toll for the disaster. The death toll figure of 242.419 came from the Chinese Seismological Service in 1988, while some sources have estimated the death toll to be at 650.000. Others range as high as 700.000. The initial estimates of 655.000 dead and 779.000 injured were released by Hebei Revolutionary Committee.

     

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NOTA: depois de geólogos chineses terem conseguido prever o sismo de 1975 de Haicheng, a 4 de fevereiro de 1975, este sismo foi uma grande derrota para a Revolução Cultural e para o Partido Comunista Chinês - a ponto de que nunca saberemos os verdadeiros números de mortos provocados por este terramoto (foram bem mais - talvez três vezes mais) do que os cerca de 250 mil oficiais...

Há 53 anos, um sismo no Peru, seguido de um deslizamento, matou mais de cem mil pessoas...

El terremoto y aluvión de Áncash de 1970, conocido localmente como el terremoto del 70, fue un sismo de magnitud 7.9 M_W sentido en toda la costa y sierra del departamento de Áncash, seguido de un alud que sepultó la ciudad de Yungay el domingo 31 de mayo de 1970, a las 15:23.

Fue el sismo más destructivo de la historia del Perú, no solo por la magnitud sino también por la cantidad de pérdidas humanas que afectó la región ancashina y varias provincias de los departamentos de Huánuco, el norte de Lima y La Libertad, dañando una extensa área de aproximadamente 1.000 km de longitud y 250 km de ancho de la costa y sierra peruana.

A raíz de esta catástrofe, en 1972 el gobierno del Perú fundó el Instituto Nacional de Defensa Civil, el cual, además de preparar a la población acerca del actuar durante un terremoto, conmemora el 31 de mayo con un simulacro de sismo a nivel nacional.

   

Características

El terremoto se inició el 31 de mayo de 1970 de 7,9 a las 3:25 p.m. Su epicentro se halló frente a las costas de las ciudades de Casma y Chimbote, en el Océano Pacífico. Su magnitud fue de 7,8 grados en la escala de Richter y alcanzó una intensidad de hasta X y XI grados en la escala de Mercalli entre Chimbote y Casma. Produjo además un violento alud en las ciudades de Yungay y Ranrahirca.

 

Efectos en el Callejón de Huaylas y el Perú 

Las muertes se calcularon en 80.000 y hubo aproximadamente de 20.000 desaparecidos, algunas fuentes elevan las víctimas mucho más alto. Los heridos hospitalizados se contabilizaron en 143.331, si bien en lugares como Recuay, Aija, Casma, Huarmey, Carhuaz y Chimbote la destrucción de edificios osciló entre 80% y 90%. Se calculó el número de afectados en 3.000.000. La Carretera Panamericana sufrió graves grietas entre Trujillo y Huarmey, lo que dificultó aún más la entrega de ayuda. La central hidroeléctrica del Cañón del Pato quedó también afectada por el embate del río Santa y la línea férrea que comunicaba Chimbote con el valle del Santa y quedó inutilizable en un 60% de su recorrido. Con esta catástrofe el Perú sacó volutariamente a la Brigada de Defensa Civil Peruana para evitar que vuelva a suceder algo tan terrible; el general Juan Velasco Alvarado, que era el presidente del país en ese entonces, tomó un barco para llevar personalmente la ayuda a Chimbote.

Sin duda alguna, la zona andina de Ancash, la pintoresca área del Callejón de Huaylas, resultó siendo el área más castigada por el terremoto. La Ciudad de Huaraz se destruyó en un 97%, el cuadrilátero de la Plaza de Armas, fue lo único importante que no se destruyó, luego del sismo, la ciudad quedó oscurecida por un negro manto de polvo, unas 10.000 personas fallecieron, solo en el "Colegio Santa Elena", murieron 400 personas. El resto de ciudades y pueblos del Callejón de Huaylas también fueron destruidos casi por completo, desde Recuay por el sur, hasta Huallanca por el norte. La tercera ciudad en importancia, Yungay terminó sepultada junto a Ranrahirca por un alud, desapareciendo 25.000 moradores. Los aludes y derrumbes obstaculizaron caminos y carreteras, y estancaron partes del Río Santa. El ferrocarril que unía a Chimbote con Huallanca desapareció. Los pobladores se disminuyeron en cantidad. Costa de Áncash y Callejón de Conchucos. En la zona costera, los efectos del sismo destruyeron grandes sectores de la Carretera Panamericana entre Huarmey y Trujillo (Departamento de La Libertad). Tanto la ciudad y el Puerto de Chimbote quedaron con averías incuantificables, en la zonas de San Pedro y Lacramarca todas las construcciones se derrumbaron, al igual que las industrias pesqueras y daño similar a las metalúrgicas, en algunas áreas el suelo se agrietó hasta expulsar chorros de agua de hasta un metro de altura, la ciudad perdió más de 2.800 habitantes. En Casma, una vieja ciudad de adobes murieron 800 personas, y más hacia el sur, en Huarmey 100. La Provincia de Bolognesi, con 1.800 víctimas, refirió cuantiosos derrumbes que incomunicaron a pueblos completos, donde se da referencias que algunas personas enterraron a sus parientes sin notificar. La zona andina siguiente al Callejón de Huaylas, conocida como Conchucos, quedó con daño moderado debido a la gran cantidad de energía que absorvió el macizo de la Cordillera Blanca, pero aún así muchas de las construcciones quedaron inhabitables, y muchas personas murieron mientras se encontraban en laborando en áreas agrícolas debido a derrumbes en los cerros contiguos. La zona quedó aislada hasta meses del resto del país.
    
El aluvión en Yungay
El fuerte y prolongado sismo de 45 segundos, provocó el desprendimiento de hielo y rocas del pico norte del nevado Huascarán, produciendo un alud estimado en 80 millones de pies³ de hielo, lodo y piedras que medía 1,5 km de ancho y que avanzó los 18 km a una velocidad promedio de 280 a 335 km/h. Durante los tres minutos que la avalancha tardó en llegar a la ciudad, la población yungaina quedó desorientada debido al eco que producía el aluvión en los cerros de la Cordillera Negra por lo que pensaron que este venía desde ese flanco y corrieron en dirección al alud. Cuando el aluvión chocó contra la pared de la quebrada del río de Ranrahirca, desvió su curso violentamente unos treinta grados en dirección sur, pero una tercera parte de la masa saltó esa barrera natural (que ya había salvado a Yungay de un aluvión en 1962) sepultando completamente a la segunda ciudad más importante del Callejón de Huaylas, mientras que la corriente mayor arrasó con el pueblo de Ranrahirca, matando en total a más de 20 000 personas.

«...Sentimos un tremendo ruido que se presentaba de ambos lados... el ruido se asemejaba al de muchos aviones... no sabíamos por donde venía ni que pasaba, en esos momentos no nos acordábamos del Huascarán... Finalmente vimos el aluvión de lodo completamente negro con más de 400 metros de altura que avanzaba botando chispas de distintos colores...»

Relato de una superviviente, en 1970

En Yungay sólo se salvaron aproximadamente 300 personas separadas en dos grupos, 90 personas que corrieron hacia el cementerio de la ciudad (una antigua fortaleza preinca elevada), y un numeroso grupo de niños que asistieron a un circo itinerante llamado Verolina y que estaba ubicado en el estadio a 700 metros de la plaza mayor.
Las labores de rescate y evacuación que puso en marcha el gobierno central sólo procedieron mediante vía aérea luego de dos días de la tragedia debido a la densa nube de polvo que se levantaba a 2700 metros sobre el nivel de la zona de la tragedia.
Así es que la provincia de Yungay alcanzó las cifras más altas en cuanto a mortalidad: 25.000 personas. El aporte internacional tuvo gran importancia en el momento de la emergencia, diversas organizaciones mundiales brindaron su apoyo. La magnitud de su cooperación no sólo fue en el momento de la emergencia sino también en la rehabilitación de la zona afectada y en el futuro desarrollo de la región. Sin embargo, la destrucción de las vías de comunicación de la zona y la falta de planeamiento le dieron una cuota de ineficiencia. Por ello es que el 28 de marzo de 1972 se crea el Instituto Nacional de Defensa Civil, para que se encargue de coordinar la prevención y la ayuda en caso de posteriores desastres.
A raíz del terremoto de 1970 que asoló varias ciudades del Callejón de Huaylas y que motivó la solidaridad de diversos países, Yungay recibió el nombre de "Capital de la Solidaridad Internacional".
   

Ruinas de la catedral de Yungay

   
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