Configuration of finite element model in a 2D cylindrical system and temperature decay curves. (a) Configuration of finite element model in a 2D cylindrical system. Color image is an example of simulated temperature increase. (b) Temperature extrapolation results of numerically synthesized data, using the same software as used onboard D/V Chikyu (tpfit3.exe). Teq, equilibrium (in situ) temperature estimated from temperature data between 60 and 600 s after penetration; Tf, threshold temperature above which the endothermic effect takes place in 2D simulation; tr, duration needed to dissociate all methane hydrate in the sediment (10% volume fraction).