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Does the lava lake of Erta ‘Ale volcano respond to regional magmatic and tectonic events? An investigation using Earth Observation data
| Content Provider | Semantic Scholar |
|---|---|
| Author | Barnie, Talfan Oppenheimer, Clive Pagli, Carolina |
| Copyright Year | 2016 |
| 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. Gold Open Access: This article is published under the terms of the CC-BY 3.0 license. The Erta 'Ale lava lake lies in the centre of the Erta 'Ale axial volcanic range, an 80 km long by c. 30 km wide ridge of aligned and coalesced volcanic centres at the northern end of the Red Sea rift system within the Afar Depression, Ethiopia (Barberi & Varet 1970; Barberi et al. 1970; see Fig. 1a). The lava lake lies at the summit of Erta 'Ale volcano, from which the volcanic range gets its name, at 600 m altitude in an elliptical caldera c. 1.6 km long by 0.9 km wide (Fig. 1b). The floor of the caldera contains two pits, one c. 200 m in diameter at the northern end (the north pit, Fig. 1c) and one c. 170 m in diameter in the centre (the south pit, Fig. 1d). The north pit contained a lava lake up to the late 1970s when the pit drained and has subsequently contained fumaroles and occasional spatter cones; the south pit still contains a lava lake today. Up to 2010, the lava lake occupied the southwestern end of the south pit and was bordered by a 'bench' of solid basalt on to which the lake would occasionally overflow. Persistent lava lakes, such as those at the Erta 'Ale, Nyiragongo, Kı̄lauea and Erebus volcanoes, are of great interest because they expose the uppermost part of an active magmatic system at the surface. This not only allows direct observations of surface motion, heat loss, gas chemistry and gas flux (e.g. Spampinato et al. 2013; Peters et al. 2014), but also direct observations of the lake level, which must respond dynamically to pressure in the magma reservoir feeding the lake, the conduit geometry, the magma ascent rate and the amount of degassing (vesiculation), among other factors (Field et al. 2012). Observations of lava lakes thereby provide valuable information that helps in understanding volcano dynamics. The effects of external influences such as tides and regional magmatic– tectonic events are of particular interest as they have been hypothesized to have a significant influence on the timing of eruptions (e.g. Darwin 1840; Palmieri 1873; Jaggar et al. 1924; Shimozuru 1975, 1987; Neuberg 2000; Hill et al. 2002; Manga & Brodsky 2006; Eggert & Walter 2009; Sottili & Palladino 2012). The history of observations linking earthquakes and volcanic eruptions separated by large distances extends back into the nineteenth century (Darwin 1840). Large earthquakes have been observed to trigger seismic swarms in magmatic regions (e.g. Hill et al. 1993) and correlations have been found From: Wright, T. J., Ayele, A., Ferguson, D. J., Kidane, T. & Vye-Brown, C. (eds) 2016. Magmatic Rifting and Active Volcanism. Geological Society, London, Special Publications, 420, 181–208. First published online March 30, 2016, http://doi.org/10.1144/SP420.15 # 2016 The Author(s). Published by The Geological Society of London. Publishing disclaimer: www.geolsoc.org.uk/pub_ethics Fig. 1. (a) Map showing the location of the Erta 'Ale lava lake and all the regional magmatic and tectonic events used in this study. DAL, Dallol dyke; DF, Dalaffilla; EA, Erta 'Ale; GOA, Gulf of Aden; JAT, Jebel al Tair; MH, Manda Hararo; NAB, Nabro; NAE, North Afar Earthquakes; ZUB, Zubair. (b) Interferogram of the Erta 'Ale summit area for epoch 2 January 2004 to 6 May 2004, pan-sharpened using a panchromatic ALI image. A lava lake is currently hosted in the south pit, but one was also present in the north pit until the 1980s. Caldera rim outlined in red, height contours in white. (c) Hill shade SRTM 30 m digital elevation model of the north pit showing the topography in February 2000 at the start of the study period. The north pit was extensively infilled with lava over the following 15 years. (d) Simple geometric model of the configuration of the south pit from late 2005 until 2010. The lava lake occupied the southwestern corner of the pit floor. The rest of the pit floor formed a flat bench, with a small arcuate ledge on the northeastern flank of the lake sometimes visible. The relative height of the lake with respect to the bench can be judged by the amount of shadowing visible on its eastern side. T. D. BARNIE ET AL. 182 |
| Starting Page | 181 |
| Ending Page | 208 |
| Page Count | 28 |
| File Format | PDF HTM / HTML |
| Volume Number | 420 |
| Alternate Webpage(s) | https://www.repository.cam.ac.uk/bitstream/handle/1810/253775/181.full.pdf?isAllowed=y&sequence=4 |
| Alternate Webpage(s) | https://doi.org/10.1144/SP420.15 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
