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Endeavour Ridge - February/March 2005

(click image for full size)map of event location  

Three magnitude 5.2, 5.1 and 4.3 earthquakes occurred on the northern Gorda Ridge segment over a 7.5 hr period beginning at 02:34Z on March 7. The SOSUS locations of these earthquakes is 42-32.1'N 126-55.2'W which is along a section of the Gorda Ridge that experienced a dike injection and seafloor eruption in 1996. As of 1400Z, SOSUS has detected 228 earthquakes from this sequence with event counts in the range of 13-27 per hour which significantly smaller than the recent Endeavour swarm during its peak in activity. Although earthquakes this large of magnitude on the ridge-axis are uncommon, the extent of a possible magmatic and hydrothermal component to this earthquake sequence (if any) is unclear and seems unlikely.

Links to these events are available at NEIC and UW seismic networks

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Update March 9: Five earthquakes occurred overnight on the ridge between the southern west valley and the northern Endeavour segment at ~48-18'N, 129-02W. Overall, however, earthquake remain at background levels.

 

Endeavour Response Cruise

cruise summary map
Response cruise summary map:
white stars = CTD casts
white lines & stars = CTD tows
blue lines & dots = camera tow
red dots = earthquake epicenters
Bathymetry is NOAA multibeam.


March 9: It appears unlikely that this February/March 2005 earthquake swarm induced corresponding expression at the seafloor (e.g., eruptive flow) or in the water column (e.g., hydrothermal chronic or event plume). The in situ and ship-board physical and chemical data from the 3 long tow-yo casts and 7 vertical casts revealed no water column signal that can be clearly associated with the recent earthquake swarm, whether magmatic or tectonic.Full report ...

camera photo camera photo
Images from camera tow, read full report from Rapid Response Cruise.

 

Other news:
Three magnitude 5.2, 5.1 and 4.3 earthquakes occurred on the northern Gorda Ridge segment over a 7.5 hr period beginning at 02:34Z on March 7.

 

Other links covering this event:
Endeavour Event Links
(Associated Press, RIDGE 2000, etc.)

 

Note there was another swarm of earthquakes in this same area in October 2004.

Map showing the location of the Endeavour earthquake swarm
Epicenter map
Epicenter plot by day
Red dots are epicenters of larger earthquakes located using 4 or more hydrophones. Black dots are smaller events that are located using 3 hydrophones and may not be as well constrained. Epicenters are plotted through March 1 (305 events).
Epicenters of earthquakes as a function of time. Black dots = 25 Feb; red dots = 27 Feb; Yellow dots = 28 Feb; White dots = 1 Mar; Pink dots = 2 Mar; Brown dots = 3 Mar.
Histogram of events plot
Time versus distance plot
Histogram of number of events vs. Time
(updated 3/24/05)
Time vs. Distance plot showing north to south distribution of earthquakes.
3D map view
3D map view
Oblique 3D view of the swarm area. Earthquake epicenters are white dots.
Oblique 3D view of the swarm area. Earthquake epicenters are white dots.

 

 

Last Updated: 07/30/07

Address inquiries to:
Oregon State University, Hatfield Marine Science Center, Cooperative Institute for Marine Resources Robert Dziak - Seismologist - robert.p.dziak@noaa.gov
Matt Fowler - Analyst - matt.fowler@noaa.gov