Earthquake-induced changes in a hydrothermal system on the Juan de Fuca mid-ocean ridge

Abstract

Hydrothermal vents on mid-ocean ridges of the northeast Pacific Ocean are known to respond to seismic disturbances, with observed changes in vent temperature. But these disturbances resulted from submarine volcanic activity; until now, there have been no observations of the response of a vent system to non-magmatic, tectonic events. Here we report measurements of hydrothermal vent temperature from several vents on the Juan de Fuca ridge in June 1999, before, during and after an earthquake swarm of apparent tectonic origin. Vent fluid temperatures began to rise 4-11 days after the first earthquake. Following this initial increase, the vent temperatures oscillated for about a month before settling down to higher values. We also observed a tenfold increase in fluid output from the hydrothermal system over a period of at least 80 days, extending along the entire ridge segment. Such a large, segment-wide thermal response to relatively modest tectonic activity is surprising, and raises questions about the sources of excess heat and fluid, and the possible effect on vent biological communities.

Role of thermal conditions in habitat selection by hydrothermal vent gastropods

“…We also observed a 5°C warming trend over 15 d at an Endeavour in-vent location. The cause is unknown but other studies record spikes in fluid heat after earthquake swarms; fluids at Endeavour Segment vents increased 4 to 11°C, and ± 5°C temperature oscillations were present for 8 to 12 d (Johnson et al 2000).…”

“…Tunnicliffe et al 1985, Chevaldonné 1991, 1996, Urcuyo 2000. At longer scales, seismic activity can initiate unpredictable temperature and vent flow changes through fluid injection or re-routing (Johnson et al 2000), cooling trends are also evident over the lifetime of a hydrothermal vent (Butterfield et al 2003).…”

High-resolution water column survey to identify active sublacustrine hydrothermal discharge zones within Lake Rotomahana, North Island, New Zealand

“…(1), the volume of 200°C water required to carry this much energy to the lake is 15.5 × 10 3 m 3 , about 0.01% of the affected lake volume (i.e., below 60 m and excluding the area east of Patiti Island). Similar short-lived increases in vent temperature following seismic swarms and in response to volcanic events have been observed at mid-ocean ridge hydrothermal systems (Baker et al, 1989;Sohn et al, 1999;Johnson et al, 2000). At least one other instance of a sudden increase in hypolimnion temperature can be identified in the historical temperature profile data (LERNZ data base) for Lake Rotomahana (see Table 1): temperature at 66 m increased by 0.5°C between 12 December 1996 and 07 January 1997 (26 days) for an average warming rate during this period of 0.019°C/day, double the historic average seasonal warming rate.…”

Bioprospecting of genetic resources in the deep seabed; Scientific, legal, and policy aspects

“…In the case of hydrothermal vent species, scientific studies have demonstrated that changes in hydrothermal flux temperatures were likely to affect vent communities. 51 A study monitoring the evolution of a new hydrothermal vent following an eruption has indicated that recruitment of new species at the site took place within a year, and that within the second year, one-third of the vent species found in the region had populated the site. 52 In less dynamic environments, species tend to grow slowly.…”