Abstract <p>A fresh eruption of the Yuzhno-Sakhalinsky mud volcano on Sakhalin Island was detected when the volcano was visited in late May 2011. The eruption was surveyed and described, data on ground movements were used to develop a model for the eruption source. Much later, when Landsat 5 and Landsat 7 satellite images were analyzed, it was found that the eruption occurred in the time interval between 19 and 211 hours after the Tohoku earthquake, Northeast Japan. The epicentral distance (on the order of 10³ km) and the magnitude (<i>M</i> = 9.0–9.1) of that earthquake satisfy the well-known relationships which are used to find the triggering threshold, i.e., the possibility for an earthquake to serve as a trigger to start the eruption of a mud volcano. It was therefore concluded that the eruption of the Yuzhno-Sakhalinsky mud volcano can have been a response to the Tohoku earthquake. If that was the case, then this would be the first reliably recorded and carefully studied response of a mud volcano to an earthquake at that great distance.</p>