Successful forecast of the 24 April 2015 eruption at Axial Seamount
Axial Seamount is the most active submarine volcano in the NE Pacific. It was chosen as the site of the world's first underwater volcano observatory called NeMO and is now a node on the new OOI Cabled Array. Axial previously erupted in 1998 and 2011. The 2011 eruption was forecast within a time window of several years based on a repeated pattern of ground deformation, but that forecast was complicated by data uncertainties. In this blog, we have documented our attempt to forecast the next eruption at Axial, using the same methods but with better measurements (funded by the National Science Foundation and NOAA). In September 2014, we made a forecast that the next eruption would occur before the end of 2015. On 24 April 2015, that eruption occurred!
- Bill Chadwick (Oregon State University and NOAA/PMEL/EOI) & Scott Nooner (University of North Carolina at WIlmington)
August 10, 2015 - New lava flows at Axial Seamount are confirmed
In late July, the University of Washington OOI Cabled Array group was able to collect mulitbeam sonar data and make one ROV dive that confirmed that new lava flows were indeed erupted at Axial Seamount in April-May. We will be going on another expedition to Axial Seamount August 14-29 with the ROV Jason and AUV Sentry on board R/V Thompson to explore and sample these new lava flows, and to collect data to continue the time-series of volcanic deformation on which the successful 2015 eruption forecast was made. You can follow the cruise blog HERE. Our next focus will be: When's the next eruption? The data we collect will help us answer that question.
April 30, 2015 - It looks like an eruption
The temperature data from the bottom pressure/tilt instruments are showing increases that suggest that lava was erupted on the seafloor somewhere nearby. Check out the latest data HERE. Below is the same long-term inflation/deflation plot as below, but now with the 2015 eruption added. Note however, that I've just eyeballed it in a vertical sense (on the Y-axis). Until we go out in August and repeat our ROV-based pressure measurements (the purple dots), we won't know exactly where it fits, nor the drift of the OOI pressure sensor. But I don't think this is too far off. See the OSU Press Release HERE.
|Plot of the long-term time-series of inflation/deflation at the center of Axial Caldera on which the 2015 forecast was based, updated with the 2015 eruption in orange (using OOI Cabled Array data).|
April 24, 2015 - Intrusion / eruption (?) event at Axial Seamount
There was a major seismic/deformation event at Axial Seamount on 23-24 April 2015. Thousands of earthquakes and sudden ground deformation (subsidence of 2.4 m over the first 3 days) were detected by the instruments on the OOI Cabled Array. The event definitely involved an intrusion of magma into the upper south rift zone (probably a dike), but it is not yet clear if there was also an eruption of lava onto the seafloor. Apparently, no lava was erupted in the summit caldera where the OOI cabled observatory instruments are located, because they all survived and there are no obvious temperature anomalies (yet). It's still possible that lava erupted either north or south of the caldera along one of the rift zones, but we won't know if that happened until a ship can get out there to look (probably not until late May at the earliest, but definitely by mid-July). Real-time seismic data from the OOI cabled observatory are being posted by William Wilcock HERE, and bottom pressure/tilt data are being posted HERE. There was an Axial Seamount science planning workshop 20-22 April in Seattle and the meeting web site has more information about this event. This is the event that we forecast last fall to occur sometime in 2015, so it's very exciting that it actually happened! We will have an expedition to Axial in mid-August to repeat our campaign-style pressure measurements to update the time-series below.
|Plot of the long-term time-series of inflation/deflation at the center of Axial Caldera on which the 2015 forecast was based, presented at the NOVAE Workshop, 20 April 2015.|
October 2014 to April 2015 - Other public presentations of the 2015 Axial Eruption Forecast
Other public presentations of the 2015 Axial eruption forecast were made on the following dates:
October 9, 2014: "Forecasting eruptions at Axial Seamount", presented at the Hatfield Marine Science Center fall seminar series, Newport, OR.
February 10, 2015: "Forecasting eruptions at Axial Seamount", presented at NOAA Headquarters, Silver Spring, MD, as part of the OneNOAA Science Seminar Series.
April 20, 2015: "Axial Inflation - Past, Present, and Future", presented at the NOVAE Workshop ("Axial Volcano - Wired and Restless - A Gathering to Explore Two Decades of Scientific Potential"), Seattle, WA. A video recording of this talk is available on the NOVAE web site HERE.
October 1, 2014 - Near-real-time data from the Ocean Observatories Initiative's (OOI) cabled observatory
The Ocean Observatories Initiative (OOI) has deployed a cabled observatory in the NE Pacific called the Regional Scale Nodes (RSN), which includes monitoring instruments in the caldera of Axial Seamount. The RSN is funded by the National Science Foundation (NSF) and is operated by the University of Washington. Some of the monitoring instruments in Axial Caldera include bottom pressure/ tilt instruments to provide near-real-time data on the ground deformation occurring there. The instruments were turned on in early September 2014. We will provide updates on those monitoring data here when the data become publically available. We may see precursory signals leading up to the next eruption, or in any case, we will certainly know if and when an eruption has occurred.
September 24, 2014 - Slide from a talk at the Monterey Bay Aquarium Research Institute (MBARI)
In August 2014, the MBARI mapping AUV (autonomous underwater vehicle) used its multibeam sonar to resurvey lines across Axial caldera that it previously ran in August 2011. A comparison of the two surveys found depth changes between 2011-2014 amounting to ~1.8 m of apparent uplift at the caldera center (the MBARI AUV data were collected and analyzed by Dave Caress). That is consistent with a continuation of the uplift rate of ~60 cm/yr that we found in our 2011-2013 pressure resurvey (see plot below), suggesting the high uplift rates appear to have continued into 2013-2014. If we add the AUV resurvey data to our BPR/MPR pressure time-series at the caldera center, it appears that Axial will have fully re-inflated (to the level just before the 2011 eruption) by the end of 2014, suggesting it might be ready to erupt again within the next year. So our new forecast is for the next eruption at Axial to occur between now and the end of 2015.
|Plot of inflation/deflation at the center of Axial Caldera with MBARI AUV datapoint added from an August 2014 resurvey.|
September 17, 2013 - Email from sea to NSF (edited slightly for clarity and brevity)
We would like to share with you some exciting results from our September 2013 expedition to Axial Seamount. We’ve been out here on R/V Thompson making dives with ROV Jason for the last two weeks and are just finishing up. Our work consisted of seafloor pressure measurements to document Axial’s volcanic inflation/deflation cycle, particularly since its 2011 eruption. We redeployed three bottom pressure recorders (BPRs), replacing one that was buried by the 2011 lava flows. We installed six new benchmarks total—two to replace two that were buried by the 2011 eruption and four to expand our coverage and tie our network to the OOI/RSN nodes. We then made ROV-based campaign-style pressure measurements (with a mobile pressure recorder, or MPR) on our array of seafloor benchmarks and downloaded data from our continuously recording bottom pressure recorders.
Here are some of our new results, which are quite surprising and unexpected to us:
1) The post-2011 eruption inflation rate is higher than we expected to see. We measured 1.22 m of uplift since August 2011, totaling 1.57 m of reinflation since the April 2011 eruption! This is an average uplift rate of 61 cm/yr!!! For comparison, during most of the period between the 1998 and 2011 eruptions, we saw steady inflation at only 15 cm/yr.
2) In addition, based on our previous models, we expected to see a gradually decreasing rate of uplift since 2011. Instead, there was an almost a doubling in the inflation rate in September 2012, recorded on both of the BPRs that were in place during 2011-2013.
3) Overall, this means that Axial has already recovered 65% of the -2.4 m of deflation that we measured during the 2011 eruption. If this inflation rate continues, it will be back to its pre-2011 level of inflation within only another year and a half (by January 2015)!
4) We don’t really know what this means in terms of forecasting the next eruption, but an inescapable conclusion is that the inflation rate since 2011 has been higher than we’ve ever measured, and this may imply that the next eruption could come sooner rather than later. Obviously, this has important implications for the OOI/RSN cabled observatory at Axial, which is not yet operational.
We hope you agree that these results are exciting. They seem to indicate that Axial’s magma supply rate has significantly increased since 2011. We feel these results also show that it is important to keep this time-series going, because it is still providing new insights and surprises, it will allow us to document the post-eruption reinflation phase for the first time, and it will provide invaluable context for the OOI/RSN observatory. As always, thanks for your interest and support of this project.
(The 2013 expedition to Axial Seamount was funded by the National Science Foundation, NOAA, and the US Navy).
|The first attached figure shows drift-corrected bottom pressure recorder (BPR) data from September 2010-September 2013, with the co-eruption deflation in blue and the post-eruption reinflation in green. ROV-based pressure measurements with a mobile pressure recorder (MPR), used to constrain BPR drift, are in purple.||The second figure shows the entire time-series from 1997-2013. The red curve shows the deflation during the 1998 eruption, the blue curve is the deflation during the 2011 eruption, and the purple dots are our campaign-style inflation measurements. This puts our new BPR data (in green) into the longer-term context.|
July 2012 - Paper published in Nature Geosciences
The following text is from a paper published in July 2012 in Nature Geoscience:
(Chadwick, W. W., Jr., S. L. Nooner, D. A. Butterfield, and M. D. Lilley (2012), Seafloor deformation and forecasts of the April 2011 eruption at Axial Seamount, Nature Geosci., 5(7), 474-477, doi:10.1038/NGEO1464.)
Now with the first documented eruption cycle at Axial, we look ahead and attempt to forecast the next event, but still with the ambiguity owing to the 1998–2000 data gap. If we assume that the cycle is time-predictable and the 1998 and 2011 eruptions both occurred at the same level of inflation, the next eruption would be expected in 2018 (left figure below). This would be 7 years between eruptions, shorter than the 13-year recurrence interval between 1998 and 2011, because the deflation in 2011 was smaller than in 1998. The other end-member possibility is that the pattern is volume-predictable. In this case, the timing of the next eruption would not be predictable, but the volume of magma removed from the summit reservoir would be, based on the time since the last eruption. For example, an eruption in 7 years would be smaller in volume than the last two, an eruption equal in size to 2011 could recur in 13 years, but one the size of the 1998 eruption would not occur until 2029 (right figure below).
We hypothesize that the pattern at Axial may be more predictable than at volcanoes on land, as its location at a spreading center means that the underlying crust is thin and it probably has a more direct, steady and simple magma supply system... We will be able to test these hypotheses by continuing geodetic monitoring at Axial, particularly once a regional cabled observatory is established as part of the Ocean Observatories Initiative.
|Two forecast scenarios for the next eruption at Axial Seamount, based on the cycle of inflation and deflation. In both, the inter-eruption MPR data (purple dots) are coregistered with the 2011 center BPR data (blue), but their exact relationship (in relative depth) to the 1998 BPR data (red) is unknown. (a) Time-predictable model in which eruptions (deflations) are triggered at a critical level of inflation and the next eruption at Axial would be expected in 2018. (b) Volume-predictable model in which the volume of the next eruption is predictable based on the time since the last one, but the date it will occur is unknown. (from Figure 3 of Chadwick et al., 2012)|