Lancang—Gengma Earthquake: A Preliminary Report on the November 6, 1988, Event and Its Aftershocks



On November 6, 1988, two earthquakes with magnitude >7 occurred within 15 minutes in southwestern Yunnan Province, China, near the Burmese border. The aftershock series in the next six weeks included three earthquakes with magnitude >6.0. Rapid deployment of accelerographs enabled us to record a large number of aftershocks, including two Ms >6 events, at near-source distances.

At 130314.5 UT on November 6 an earthquake with Ms = 7.6 (U.S. Geological Survey Ms = 7.3) occurred 40 km northwest of Lancang (Figure 1). Thirteen minutes later another large event with Ms = 7.2 (USGS Ms 6.4) occurred 60 km north-northwest of the first shock. By December 20 more than 600 aftershocks with Ms >3 had occurred.