PMEL Earth-Ocean Interactions logo

Gorda Ridge - March 2005

epicenter map
Epicenter map of recent Gorda quakes. (click for full size)
histogram graph
Histogram of Gorda quakes. (click for full size image)

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: Earthquake activity has fallen off substantially. In summary, given that this recent sequence began with a large magnitude earthquake (5.2) and was followed by a relatively low number of events per hour that is consistent with aftershock activity, it seems likely this was a tectonic sequence and did not have a magmatic/hydrothermal component.


Last Updated: 07/30/07

Address inquiries to:
Oregon State University, Hatfield Marine Science Center, Cooperative Institute for Marine Resources Robert Dziak - Seismologist -
Matt Fowler - Analyst -