This study is related to a case concerning a methane explosion occurred inside the excavation chamber of an EPB-TBM in Silivri-Istanbul on the 20th of May in 2010. The authors of the paper were nominated as official inspectors of the court. A literature survey is first carried out in order to review similar accidents happened worldwide. Causes and effects of the explosion are analyzed later in detail. Precautions against methane emission are also summarized. It is concluded that a methane explosion inside the excavation chamber of an EPB-TBM is a very rare case and was not reported in the literature as the authors' best knowledge. Oxygen necessary for methane explosion came from the foam used in the excavation chamber. Explosion occurred probably due to sparking caused by friction between screw conveyor and its casing. It is recommended that further research studies should focus on producing more secure foams being functional without oxygen, a methane detector should also placed inside the chamber with a power cutoff system. (C) 2011 Elsevier Ltd. All rights reserved.