1 DR. TEAL: You looked at this whole system for a couple of years 



2 and one of the things that perhaps controls them in the long term are 



3 occasional events of much greater severity than anything you observed. 



4 I guess the question is: Were you out there or did your 



5 observations encompass any particularly violent, unusually violent 



6 activity? 



7 DR. BUTMAN: No. We maintained the station at LCB in the canyon 



8 head at 300 meters for 2 full years. If you look at the statistics, and 



9 that was five deployments of about 6 months each, and if you look at the 



10 statistics by deployment, it doesn't change very much. 



11 I was actually pretty surprised that there may still be other 



12 catastrophic events, but for that 2-year period, you could have picked 



13 any 2 months and they would have been representative of the other 24 



14 months. 



15 I think that goes back to the spectra that I showed, that there is 



16 very little low frequency variability in the canyons at periods longer 



17 than several 100 hours. Most of the variability is in those very high 



18 frequencies, and that changes rapidly on a daily basis. 



19 There is some suggestion that that high frequency variability is 



20 modulated by processes outside the canyon. For example, there is a very 



21 weak statistical correlation between the presence of warm-core rings and 



22 the strength of those high frequency fluctuations. 



23 We needed about a 2-year data record to start seeing that 



24 correlation, and it was marginal at best. The most obvious correlation 



25 was the presence of rings on the outer edge of the shelf, causing flow 



26 over the outer edge of the slope and the top part of the canyon. 



27 I also looked very carefully trying to correlate meteorological 



28 events on the shelf with flows within the canyon. There, again, the 



29 correlation is marginal at best. I think Mike, though, will show some 



30 very strong seasonal fluctuations in the sediment flux into the canyon 



31 from the shelf. 



32 In terms of the strength of the flows within the canyons, the 



33 correlation between what's going on in the shelf and what's going on 



34 within the deeper part of the canyon was marginal. 



32 



