1970 Tonghai earthquake
Encyclopedia
The 1970 Tonghai earthquake occurred on 4 January 1970 in Tonghai, China
. The rupture originated on the local Yunnan Province’s Red River fault
, which had not experienced an earthquake above magnitude 7 since 1700. The earthquake had a magnitude of 7.7 and killed at least 15,000 people, making it one of the deadliest in the history of China. The tremor caused between US$5 to $25 million in damage,This would cost roughly US$28,194,000 to $140,968,000 in 2008 US$. See Inflation Calculator. felt over an area of 8781 km (5,456.3 mi). In Hanoi
, North Vietnam
, almost 483 km (300.1 mi) from the epicenter, victims left their homes as the rupture rumbled through the city.
Occurring during the height of the Cultural Revolution
, it was not widely publicized by the Chinese government for well over a decade. The amount of aid and finances distributed was described by the Beijing Morning Post as "pathetically small". Much of the aid provided to survivors was in "spiritual" form, including Mao Zedong badges
and condolence letters. Nevertheless, the earthquake was among the first to be studied over a long term by the Chinese government. It was cited as one of the reasons behind creating the largest earthquake monitoring system in China, 25 years later.
Earthquakes in the southwestern part of this province, like the 1970 Tonghai event, occur less often than the provincial average. The Red River fault, the fault line on which this quake is alleged to have occurred, has lacked seismological activity as a whole. Red River temblors generally rise at high angles, as shown in a 1962 Ministry of Geology report. Marking in sedimentary rocks indicate that several large earthquakes formed on the fault during the Pleistocene
and Holocene
epoch
s. Until this quake, no earthquake above magnitude 7.0 on the Richter scale had occurred on this fault since about 1700, and the fault was believed to be "dead". Since the 1970 Tonghai rupture, it is believed that the Red River fault is instead experiencing a long seismic gap
similar to that of the Japan Median Tectonic Line
, on which no major temblor has formed since 700 but produced massive ones during the Holocene epoch.
, a city of about one million people at the time, and 97 km (60.3 mi) northwest of Gejiu (Kokiu), which has a population of 180,000; this area was mainly a tobacco
-growing region. Effects of the rupture were felt over an area of 8781 km (5,456.3 mi). In Hanoi
, North Vietnam
, almost 483 km (300.1 mi) from the epicenter, victims left their homes as the rupture rumbled through the city.
The earthquake measured 7.7 on the Richter scale. It killed 15,621 people, making it the third deadliest in China during the 20th century, and injured an additional 26,783. The tremor caused between US$5 to $25 million in damage. A Reuters news report, the only one in the immediate aftermath, mentioned the recording of a "severe" quake by Hong Kong's Royal Observatory
and cited an unconfirmed report that it might have destroyed part of Kunming. It caused 50 km (31.1 mi) of visible surface faulting on the Tonghai Fault. There was a maximum horizontal offset of 2.5 m (8 ft) and vertical offset of about 0.5 m (1.5 ft). As a result of inversion techniques, scientists were able to decide that several events comprised the surface faulting. This further confirmed that the earthquake, along with a later earthquake in Yunnan Province in 1973, corresponded to a fault within the area.
books and badges in his honor to victims as part of the relief effort, and survivors also received 14,350 sympathy letters. However, the amount of aid and finances distributed was described by the Beijing Morning Post 30 years later as "pathetically small."
The details of the earthquake were not widely publicized by Chinese authorities until about 18 years after its occurrence. In China's first decades of Communist rule, its policy was to not disclose natural disasters or accidents unless foreigners were injured. While the Chinese official press had not released a comprehensive report, Reuters
and the Royal Hong Kong Observatory
both released information soon after the disaster. At the time of the quake, the Xinhua News Agency
briefly mentioned a smaller magnitude quake but did not provide information on damage or casualties.
On 19 November 1988, nearly nineteen years later, Chen Zhangli of the State Seismology Bureau, speaking at a news conference for another earthquake that had recently occurred, estimated the death toll of the 1970 quake to be 10,000. He did not give a reason why his government had not previously disclosed this knowledge. Government officials from China released a different estimate in 2000, putting the death toll at 15,621. China published the estimate after a memorial service for survivors and relatives was held in Yuxi
on January 5. A Yuxi Seismology Bureau official noted that the information had been classified for "political reasons" and the death toll estimate had been known among bureaucrats as early as 1997.
Twenty-five years after the earthquake, the largest earthquake-monitoring network in China was established in Yunnan Province. It set up earthquake offices in every county to prepare for another large rupture. The 1970 Tonghai earthquake was cited as one of the reasons behind creating the monitoring system.
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...
. The rupture originated on the local Yunnan Province’s Red River fault
Red River fault
The Red River Fault is a major fault in Yunnan, China and Vietnam which accommodates continental China's southward movement It is coupled with that of the Sagaing Fault in Myanmar which accommodates the Indian plate's northward movement, with the land in between faulted and twisted clockwise. ...
, which had not experienced an earthquake above magnitude 7 since 1700. The earthquake had a magnitude of 7.7 and killed at least 15,000 people, making it one of the deadliest in the history of China. The tremor caused between US$5 to $25 million in damage,This would cost roughly US$28,194,000 to $140,968,000 in 2008 US$. See Inflation Calculator. felt over an area of 8781 km (5,456.3 mi). In Hanoi
Hanoi
Hanoi , is the capital of Vietnam and the country's second largest city. Its population in 2009 was estimated at 2.6 million for urban districts, 6.5 million for the metropolitan jurisdiction. From 1010 until 1802, it was the most important political centre of Vietnam...
, North Vietnam
North Vietnam
The Democratic Republic of Vietnam , was a communist state that ruled the northern half of Vietnam from 1954 until 1976 following the Geneva Conference and laid claim to all of Vietnam from 1945 to 1954 during the First Indochina War, during which they controlled pockets of territory throughout...
, almost 483 km (300.1 mi) from the epicenter, victims left their homes as the rupture rumbled through the city.
Occurring during the height of the Cultural Revolution
Cultural Revolution
The Great Proletarian Cultural Revolution, commonly known as the Cultural Revolution , was a socio-political movement that took place in the People's Republic of China from 1966 through 1976...
, it was not widely publicized by the Chinese government for well over a decade. The amount of aid and finances distributed was described by the Beijing Morning Post as "pathetically small". Much of the aid provided to survivors was in "spiritual" form, including Mao Zedong badges
Chairman Mao badge
Chairman Mao badge is the name given to a type of pin badge displaying an image of Mao Zedong that was ubiquitous in the People's Republic of China during the early period of the Cultural Revolution, from 1966 to 1971. The term is also used for badges associated with Mao that do not actually have...
and condolence letters. Nevertheless, the earthquake was among the first to be studied over a long term by the Chinese government. It was cited as one of the reasons behind creating the largest earthquake monitoring system in China, 25 years later.
Background and tectonics
Yunnan Province, the epicentral region, has endured many earthquakes, and is one of the most seismically active provinces in China. The earliest earthquake recorded there was in the 9th century; however, moderate to strong ones have been observed since the 15th century. Since the 9th century, 32 earthquakes with a magnitude of 7 or greater have occurred in the province. Shallow strike-slip faulting is a characteristic of Yunnan quakes.Earthquakes in the southwestern part of this province, like the 1970 Tonghai event, occur less often than the provincial average. The Red River fault, the fault line on which this quake is alleged to have occurred, has lacked seismological activity as a whole. Red River temblors generally rise at high angles, as shown in a 1962 Ministry of Geology report. Marking in sedimentary rocks indicate that several large earthquakes formed on the fault during the Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
and Holocene
Holocene
The Holocene is a geological epoch which began at the end of the Pleistocene and continues to the present. The Holocene is part of the Quaternary period. Its name comes from the Greek words and , meaning "entirely recent"...
epoch
Epoch (geology)
An epoch is a subdivision of the geologic timescale based on rock layering. In order, the higher subdivisions are periods, eras and eons. We are currently living in the Holocene epoch...
s. Until this quake, no earthquake above magnitude 7.0 on the Richter scale had occurred on this fault since about 1700, and the fault was believed to be "dead". Since the 1970 Tonghai rupture, it is believed that the Red River fault is instead experiencing a long seismic gap
Seismic gap
A seismic gap is a segment of an active fault that has not slipped in an unusually long time when compared with other segments along the same structure. Seismic gap hypothesis/theory states that, over long periods of time, the displacement on any segment must be equal to that experienced by all...
similar to that of the Japan Median Tectonic Line
Japan Median Tectonic Line
, also Median Tectonic Line , is Japan's longest fault system. It connects with the Itoigawa-Shizuoka Tectonic Line , the left blue line on the map, and the Fossa Magna, the pink shaded region....
, on which no major temblor has formed since 700 but produced massive ones during the Holocene epoch.
Damage and casualties
The epicenter of the quake was about 121 km (75.2 mi) southwest of KunmingKunming
' is the capital and largest city of Yunnan Province in Southwest China. It was known as Yunnan-Fou until the 1920s. A prefecture-level city, it is the political, economic, communications and cultural centre of Yunnan, and is the seat of the provincial government...
, a city of about one million people at the time, and 97 km (60.3 mi) northwest of Gejiu (Kokiu), which has a population of 180,000; this area was mainly a tobacco
Tobacco
Tobacco is an agricultural product processed from the leaves of plants in the genus Nicotiana. It can be consumed, used as a pesticide and, in the form of nicotine tartrate, used in some medicines...
-growing region. Effects of the rupture were felt over an area of 8781 km (5,456.3 mi). In Hanoi
Hanoi
Hanoi , is the capital of Vietnam and the country's second largest city. Its population in 2009 was estimated at 2.6 million for urban districts, 6.5 million for the metropolitan jurisdiction. From 1010 until 1802, it was the most important political centre of Vietnam...
, North Vietnam
North Vietnam
The Democratic Republic of Vietnam , was a communist state that ruled the northern half of Vietnam from 1954 until 1976 following the Geneva Conference and laid claim to all of Vietnam from 1945 to 1954 during the First Indochina War, during which they controlled pockets of territory throughout...
, almost 483 km (300.1 mi) from the epicenter, victims left their homes as the rupture rumbled through the city.
The earthquake measured 7.7 on the Richter scale. It killed 15,621 people, making it the third deadliest in China during the 20th century, and injured an additional 26,783. The tremor caused between US$5 to $25 million in damage. A Reuters news report, the only one in the immediate aftermath, mentioned the recording of a "severe" quake by Hong Kong's Royal Observatory
Hong Kong Observatory
Hong Kong Observatory is a department of the Hong Kong government. The Observatory forecasts weather and issues warnings on weather-related hazards...
and cited an unconfirmed report that it might have destroyed part of Kunming. It caused 50 km (31.1 mi) of visible surface faulting on the Tonghai Fault. There was a maximum horizontal offset of 2.5 m (8 ft) and vertical offset of about 0.5 m (1.5 ft). As a result of inversion techniques, scientists were able to decide that several events comprised the surface faulting. This further confirmed that the earthquake, along with a later earthquake in Yunnan Province in 1973, corresponded to a fault within the area.
Scientific study
The earthquake was among the first to be studied over a long term by the Chinese government. More than 40 Chinese seismologists, engineers, and geologists visited the disaster zone to conduct research into the cause and damage of the earthquake; some spending as much as a year collecting soil samples and recording other primary research evidence for future study. Such data was collected over a broad area of almost 1400 towns within the area.Reaction
According to the Reuters report, the survivors came together to "fight against the disaster". Much of the aid provided to survivors was in "spiritual" form. The Chinese government sent tens of thousands Quotations from Chairman Mao ZedongQuotations from Chairman Mao Zedong
Quotations from Chairman Mao Tse-Tung , is a book of selected statements from speeches and writings by Mao Zedong, the former leader of Chinese Communist Party, published from 1964 to about 1976 and widely distributed during the Cultural Revolution...
books and badges in his honor to victims as part of the relief effort, and survivors also received 14,350 sympathy letters. However, the amount of aid and finances distributed was described by the Beijing Morning Post 30 years later as "pathetically small."
The details of the earthquake were not widely publicized by Chinese authorities until about 18 years after its occurrence. In China's first decades of Communist rule, its policy was to not disclose natural disasters or accidents unless foreigners were injured. While the Chinese official press had not released a comprehensive report, Reuters
Reuters
Reuters is a news agency headquartered in New York City. Until 2008 the Reuters news agency formed part of a British independent company, Reuters Group plc, which was also a provider of financial market data...
and the Royal Hong Kong Observatory
Hong Kong Observatory
Hong Kong Observatory is a department of the Hong Kong government. The Observatory forecasts weather and issues warnings on weather-related hazards...
both released information soon after the disaster. At the time of the quake, the Xinhua News Agency
Xinhua News Agency
The Xinhua News Agency is the official press agency of the government of the People's Republic of China and the biggest center for collecting information and press conferences in the PRC. It is the largest news agency in the PRC, ahead of the China News Service...
briefly mentioned a smaller magnitude quake but did not provide information on damage or casualties.
On 19 November 1988, nearly nineteen years later, Chen Zhangli of the State Seismology Bureau, speaking at a news conference for another earthquake that had recently occurred, estimated the death toll of the 1970 quake to be 10,000. He did not give a reason why his government had not previously disclosed this knowledge. Government officials from China released a different estimate in 2000, putting the death toll at 15,621. China published the estimate after a memorial service for survivors and relatives was held in Yuxi
Yuxi
Yuxi is a prefecture-level city in the Yunnan province of the People's Republic of China. The administrative center of Yuxi is Hongta District. Yuxi is approximately 90 km south of Kunming.-Geography:...
on January 5. A Yuxi Seismology Bureau official noted that the information had been classified for "political reasons" and the death toll estimate had been known among bureaucrats as early as 1997.
Twenty-five years after the earthquake, the largest earthquake-monitoring network in China was established in Yunnan Province. It set up earthquake offices in every county to prepare for another large rupture. The 1970 Tonghai earthquake was cited as one of the reasons behind creating the monitoring system.