Endeavour Ridge - February/March 2005
(click
image for full size) |
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
.
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.
 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 ...
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| 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 |
|
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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. |
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Histogram
of number of events vs. Time (updated 3/24/05) |
Time
vs. Distance plot showing north to south distribution
of earthquakes. |
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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:
Robert
Dziak - Seismologist - robert.p.dziak@noaa.gov
Matt
Fowler - Analyst - matt.fowler@noaa.gov