1970 Tonghai earthquake

in Tonghai County Yunnan, the epicentral region, is one of the more seismically active Chinese provinces. The earliest earthquake recorded there was in the 9th century; however, moderate to strong ones have been observed since the 15th century. Earthquakes in southwestern Yunnan, such as the 1970 Tonghai event, are less frequent than in other parts of the province. The Red River Fault, the fault on which this quake is alleged to have occurred, has lacked seismological activity as a whole. Marking in sedimentary rocks indicate that several large earthquakes formed on the fault during the Pleistocene and Holocene epochs. 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. ==Damage and casualties==

was from the epicenter The epicenter of the quake was about southwest of Kunming and northwest of Gejiu; The earthquake measured 7.1 on the moment magnitude scale. It may have killed more than 15,000 people, making it the third deadliest in China during the 20th century, 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 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). ==Aftermath==

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 1,400 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. In China's first decades of Communist rule, its policy was to not disclose natural disasters or accidents unless foreigners were injured. China published the estimate after a memorial service for survivors and relatives was held in Yuxi on 5 January. ==See also==