Field observations indicate the Mw 6.8 Tarlay, Myanmar, earthquake of 24 March 2011 resulted from the rupture of a short section of the left‐lateral Nam Ma fault. We document coseismic left‐lateral offsets that range from approximately 10 cm to about 2 m along a 19 km long section of the fault, based upon both field investigations and the interpretation of high‐resolution satellite imagery. Comparison of these early field and later remote measurements suggests that most of the paddy‐field offsets became obscured within a year or two. Our measurements indicate the magnitude of sinistral offset decreases gradually eastward from the epicentral area to the rupture terminus within the Tarlay basin, along the southern edge of a 2–3 km wide transtensional stepover.
Our measurements confirm that the earthquake resulted from rupture of a structurally distinct segment of the Nam Ma fault, bounded on the west by the fault’s terminus and on the east by the Tarlay basin stepover. If the 215 km Nam Ma fault were to rupture entirely in a single event, the magnitude of the resulting earthquake would likely be about Mw 7.7.
Online Material: Field observations and photos after the 2011 Tarlay earthquake, table of offset, and maps with location and offset.