Rupture along the Great Sumatran fault, Indonesia, during the earthquakes of 1926 and 1943

While investigating features of Quaternary displacement along the Great Sumatran fault zone in the Padang Highlands of Sumatra, Indonesia (Figure 1), the authors incidentally came across heretofore unreported evidence of significant surficial displacements along the fault during the M_s = 6¾ earthquake of 28 June 1926 and the M_s = 7.6 earthquake of 9 June 1943. In both cases, eyewitness reports by long-term local residents allowed unequivocal documentation of the location and nature of the surficial fault displacements associated with the earthquakes, although it was only through the use of vertical aerial photographs to locate the active fault trace that it was possible to concentrate the questioning in promising areas. In every case, it was thus possible to locate the primary active fault trace to within a few hundred meters before commencing the search for local eyewitnesses