Does the lava lake of Erta ‘Ale volcano respond to regional magmatic and tectonic events? An investigation using Earth Observation data

T D Barnie,C Oppenheimer,C Pagli

doi:10.1144/sp420.15

Abstract

Abstract Erta ‘Ale volcano lies at the centre of the Erta ‘Ale rift segment in northern Afar, Ethiopia and hosts one of the few persistent lava lakes found on Earth in its summit caldera. Previous studies have reported anecdotal evidence of a correlation between lake activity and magmatic and tectonic events in the broader region. We investigated this hypothesis for the period 2000–15 by comparing a catalogue of regional events with changes in lake activity reconstructed from Earth Observation data. The lava lake underwent dramatic changes during the study period, exhibiting an overall rise in height with concomitant changes in geometry consistent with a change in heat energy balance. Numerous paroxysms occurred in the lake and in the north pit; a significant dyke intrusion with subsequent re-intrusions indicated a role for dykes in maintaining the lake. However, despite some coincidences between the paroxysms and regional events, we did not find any statistically significant relationship between the two on a timescale of days to weeks. Nevertheless, changes in lake activity have preceded the broad increase in regional activity since 2005 and we cannot rule out a relationship on a decadal scale.

Highlights

Persistent lava lakes, such as those at the Erta ‘Ale, Nyiragongo, Kılauea and Erebus volcanoes, are of great interest because they expose the uppermost part of an active magmatic system at the surface
We looked for spike trains in periods without major thermal anomalies, but where relatively high MODerate resolution Imaging Spectrometer (MODIS) fire radiative power (FRP) values and a high lava lake level indicated (1) a comparatively high level of thermal output and (2) that the Spinning Enhanced Visible and Infrared Imager (SEVIRI) instrument may have a direct view of the lake surface; we identified some extra spike trains in 2008, 2009 and 2011
As the lake level rises, the geometry of the lava lake appears to change in response to increased heat loss, becoming smaller and more circular with reduced radiant power output, imposing a maximum height that the lake can reach of between c. 40 and c. 60 m above the south pit rim, which may reflect a fundamental constraint on the persistence of lava lakes

Summary

Introduction

Persistent lava lakes, such as those at the Erta ‘Ale, Nyiragongo, Kılauea and Erebus volcanoes, are of great interest because they expose the uppermost part of an active magmatic system at the surface. We integrated a variety of Earth Observation datasets across a range of spatial and temporal scales to reconstruct changes in the behaviour of the lake over the past decade, extending the work of Oppenheimer & Francis (1997), Wright & Pilger (2008), Field et al (2012) and Murphy et al (2013). We compared this record with that of the magmatic– tectonic events to investigate the influence of potential external forcings. The range is a rift segment transitional between continental rifting and seafloor spreading (Hayward & Ebinger 1996)

Methods

Results

Discussion

Conclusion