Earthquakes more precisely located on the Mid-Atlantic Ridge

What is it about?

Swarms of earthquakes in remote locations are usually too poorly located to work out if multiple or single faults move during them, hence it is difficult to work out the mechanical evolution of such areas. In our new article (https://doi.org/10.1016/j.tecto.2021.229063), we show how they can be better located using recordings from regional seismometer networks. We found in one swarm in 2016 that multiple faults had moved across the rift valley of the Mid-Atlantic Ridge. Furthermore, we estimated depths of earthquakes using differences in time between waves coming directly from the earthquake and those bounced off the ocean surface.

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Why is it important?

There is a gap in our observations of earthquakes between global seismological methods (which give us many earthquakes but usually poorly located) and studies with ocean bottom seismometers (which give us many earthquakes locally that are very well resolved, but are expensive to carry out and therefore there are few of them, mostly limited to months in duration). Along with earthquakes from hydrophone networks, the methods we use can help to fill the gap, also with estimates of earthquake depth. The swarms were found here to involve earthquakes occurring across broad areas of the rift valley. Within each swarm, we did not find the earthquake locations progressing as might otherwise indicate intrusion of a volcanic dike.