Samples depleted in dissolved chloride are no doubt the result of phase separation followed subsequently by the mixing of vapors with seawater. Reaction zone pressures of 450 to 500 bars indicate fluid formation at depths of about 1 to 2 km below the seafloor. This is supported by seismic data suggesting that a large magma chamber exists under the region at approximately 2.5km below the seafloor. In 1999, similar vent sites were sampled at Juan de Fuca Ridge's MEF, 3 months after the seismic event. That study showed substantially lower dissolved chloride values at certain vent sites. In particular, Sully and Bastille, the only vents sampled in both 1999 and 2005, showed dissolved chloride values of 39 and 208 mmolal respectively, vs. 455 and 461 in the current study. This suggests the system was much hotter immediately following the event than in 2005, as lower chloride values correspond to phase separation at higher temperatures closer to the seafloor. Chloride values in excess to seawater at Mothra in the current study further suggest cooling in the reaction zone following the seismic event. At Mothra, fluids failing to reach temperatures sufficiently high for phase separation and mixing with brines may have been expelled from vent and would have dissolved chloride values similar to those observed. Other elemental variances remain similar throughout both studies, although at higher concentrations in the current study.