2015 Axial Seamount Eruption

Most of the volcanic activity on the planet occurs under the ocean. However, more often than not, no one notices these volcanic eruptions as they usually occur miles below the sea surface. Historically, in order to capture a live eruption, scientists had to find themselves in the right place at the right time. On April 24, 2015, however, the Axial Seamount volcano erupted and we saw it in real-time through the OOI Regional Cabled Array, making this the first undersea volcanic eruption ever recorded by an in situ cabled observatory. Over the course of a 24-hour period, several Cabled Array instruments detected ~8,000 earthquakes and a seafloor drop of 2.4 m.

The data within this nugget are from a bottom pressure and tilt sensor deployed on the Axial Seamount. The drop in the seafloor can be observed in these pressure data as the pressure exerted on the sensor (and seafloor) is increased from the extra weight of water in the overlying water column as the seafloor falls.

This drop in the seafloor or “deflation” occurs rapidly during an eruption and is caused by the ejection of magma into the ocean. Between eruptions, the magma is recharged causing the sea floor to slowly rise up again, a process referred to as inflation. Scientists have observed that eruptions at the Axial volcano occur when an inflation threshold (i.e. seafloor height) is reached making it possible to potentially predict future eruptions. You can read more about their work in the Related Publications Section and see much of the data and forecasts in the list of Additional Resources.