Time Critical Studies

TCS overview

This TCS overview is also available as a 1MB, 11-page pdf download (includes all figures).

Introduction to TCS

The Time-Critical Studies (TCS) Theme of Ridge 2000 focuses on observations of the immediate geochemical and geobiological consequences of magmatic and tectonic events along the global mid-ocean ridge system.

Much of the funding in this program centered on the Juan de Fuca and Gorda Ridges (Figure 1), which are within the range of the U.S. Navy’s Northeast Pacific Sound Surveillance System (SOSUS). NOAA’s T-Phase Monitoring Program has accessed SOSUS in real-time since 1993, providing the TCS community with detection of seismicity associated with eruptive or tectonic activity along these two ridges (Figure 2). This remote detection of earthquake swarms along the N.E. Pacific mid-ocean ridge coupled to NSF funding for pre-event staging of equipment and supplies has allowed directed and increasingly well-organized field responses to the event site. Major rapid and follow-up response cruises have been successfully mounted to 1993 CoAxial, 1996 and 2001 Gorda Ridge, the 1998 Axial Volcano, and 2001 Middle Valley magmatic episodes. The logistical approach required to study these events has been greatly facilitated by the RIDGE/Ridge 2000 programs and collaboration between university, NOAA and Canadian investigators. Not only have our studies of these events significantly impacted our ideas on the nature of crustal accretion, but they also have led to the discovery and preliminary documentation of a previously unrecognized biomass reservoir that lives below the seafloor and is swept out during these cataclysmic events, and to increased appreciation of the formation and thermal, chemical and biogeochemical implications of the “Event Plumes” commonly associated with seafloor magmatic events.

Recent funding in this program included response cruises to the East Pacific Rise following the 2005/2006 eruption near 9¡50'N, and a response cruise in the NE Lau Basin (see TCS News webpage).
Link to video clips of West Mata Submarine Volcano eruption on NOAA Vents webiste.

Insights from TCS

Some examples of new insights into the causes and implications of MOR magmatic (and tectonic) events that have been derived from TCS efforts include:

SOSUS system is an effective means of remotely detecting MOR seismic events (Figure 2);
SOSUS detected seismic events can be associated with episodes of significant magmatic activity within the crust and seafloor eruptions;
Events occur along the MOR with high frequency (>0.5 year within Northeast Pacific SOSUS system in 1993–2003);
Event plumes are commonly associated with seismic events; multiple event plumes can be released during a seismic event (Figure 3 and Figure 4). (At least 7 event plumes have been encountered in the Northeast Pacific MOR);
Thermochemical fluxes of event plumes have a distinct signature, differing qualitatively from those of chronic plumes;
Total thermochemical fluxes associated with events change rapidly with time following the event (Figure 5);
Subseafloor populations of extremophiles are released in association with events (Figure 6);
Lagrangian drifter floats (e.g., RAFOS) are an effective means of tracking event plumes for time series observations of physical and biogeochemical processes that ultimately link event thermochemical fluxes to the global ocean (Figure 4).
210Po-210Pb and 210Pb-226Ra dating of young-appearing lavas allow determination of high-resolution eruption ages, eruption durations, and age offset with antecedent topography. They can also provide event “verification” in cases where no seismic data is available at suspected eruption locales (Figure 10 and Ridge 2000 Events 3, Spring 2005, 28-30).

Time Critical Studies

TCS overview

Introduction to TCS

Insights from TCS

Resources