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| Exciting News From Ridge 2000 |
Hi All, There was supposed to be a press release on this on May 3rd and there may have been and I just didn't catch it yet. I thought maybe Chris or some others might be interested in this news item....Petra Exciting News from the East Pacific Rise 9°50'N Site!! Information obtained early this week indicates that significant new activity is occurring at the EPR 9N Integrated Studies Site (ISS). While recovering/re-deploying OBSs that have been recording seismicity at the site for several years, the pattern of problematic instrument recoveries suggested possible eruption. Water column measurements were done right away and they show strong, anomalous venting. Both the problematic OBS recoveries and level of apparent venting differ from what was observed a year earlier. In the context of previously known increased seismicity rates and changes in fluid chemistry over the past 2 years, the new information (detailed below) provides exciting indication that the site may have erupted quite recently. Maya Tolstoy and Felix Waldhauser have been conducting seismicity studies at the EPR 9N site for several years, with OBSs being turned around approximately annually. This year the turn around was scheduled as a few-day part of a cruise led by Don Forsyth and Alberto Saal, which focused on transform faults on the southern EPR. Robert Weekly was the scientist from Maya's seismicity analysis team that sailed. When Forsyth's group completed their work, the R/V Knorr transited to the EPR ISS and deployed 12 OBSs for the next years recording. Attempts to recover the 12 OBSs deployed the previous year failed in several cases. The northernmost OBS and 3 off-axis OBSs were unaffected by whatever problem was experienced by the others. Because Maya, and others studying fluid chemistry changes at the site, had predicted a likelihood of fairly imminent eruption, all involved were quick to relate the pattern of problem OBSs with possibility of recent lava flow within the instrument array. Ed Baker's MAPR was deployed to check this initial interpretation. The strength of the water column anomalies reach 3-5 times that seen by Baker about 6 months after the 1991 eruption at this site. With this evidence in hand, a dredge was done (with MAPR attached to wire) and iridescent, glassy basalt was recovered- shards and fragments of solidified lava flow. In the course of this initial event characterization work, at least one of the OBSs newly-deployed on the axis stopped responding to acoustic queries. This suggests that activity could be ongoing. Maya will begin analysis of the data from the 4 recovered OBSs as soon as possible after the ship arrives in San Diego May 3. Ken Rubin will analyze some of the rock sample to obtain dates. Sample handling has taken care to preserve possible biofilms and Constantino Ventriani and Stefan Sievert will analyze these. Additional rock analyses will be conducted by Saal and several others. Efforts to mount response cruise(s) are well underway, led by Jim Cowen with considerable work by Dan Fornari, the EPR Site Coordinator, and a number of others. There are some excellent options within the next 1-8 weeks that are being pursued. Your input on studies that could be done during such response cruise(s) is welcome. You may post comments to the R2K online discussion website, contact the R2K Office, or get in touch with Jim Cowen, lead PI for R2K Time Critical Studies: http://www.ridge2000.org/science/discussion |
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