Abstract

Five moderate‐sized earthquakes struck the Yingjiang area (China–Myanmar border), where there is a lack of historical earthquakes, and provided us an opportunity to study the seismogenic fault. We relocate sequences via the hypoDD method using the cross‐correlated arrival times. The phase picking errors by the human analysts had only 0.01 s difference before and after 2009; however, the P‐phase picking precision increased from the tenths to the hundredths place after 2009, and the relocation errors of hypoDD simultaneously decreased by a factor of 2. The rupture dimensions are about 2–4 km for the five sequences. The hypoDD relocation errors are only 0.36 or 0.63 km for the two test clusters, which are much smaller than the dimensions of the rupture areas. The synthetic tests show no location bias from the distribution of the Yunnan regional seismic network. The relocations identify four linear features with the northwest, north‐northwest, or northeast direction for the 21 March 2008, 3 September 2008, 10 March 2011, and 30 May 2014 sequences orthogonal to the known major fault traces. The relocations also suggest that the 10 March 2011 sequence is on a double‐layered fault dipping roughly 71° to the southwest. Focal mechanisms reveal a mixture of strike‐slip, normal, and reverse faulting.

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