Catalysis of the reaction: (EE)-geranyllinalool + NADPH + O2 = 4,8,12-trimethyl-1,3,7,11-tridecatetraene + NADP+ + 2 H2O. It is unknown whether this reaction proceeds by the direct release of the 4-carbon compound but-1-en-3-one, or whether the substrate is first degraded to C18-farnesylacetone and then cleaved to produce 4,8,12-trimethyl-1,3,7,11-tridecatetraene (TMTT) and acetone.