| Autor: |
Garvin, J. B., Slayback, D. A., Ferrini, V., Frawley, J., Giguere, C., Asrar, G. R., Andersen, K. |
| Zdroj: |
Geophysical Research Letters; April 2018, Vol. 45 Issue: 8 p3445-3452, 8p |
| Abstrakt: |
We have monitored a newly erupted volcanic island in the Kingdom of Tonga, unofficially known as Hunga Tonga Hunga Ha'apai, by means of relatively frequent high spatial resolution (~50 cm) satellite observations. The new ~1.8 km2island formed as a tuff cone over the course of a month‐long hydromagmatic eruption in early 2015 in the Tonga‐Kermadecvolcanic arc. Such ash‐dominated eruptions usually produce fragile subaerial landscapes that wash away rapidly due to marine erosion, as occurred nearby in 2009. Our measured rates of erosion are ~0.00256 km3/year from derived digital topographic models. Preliminary measurements of the topographic expression of the primary tuff cone over ~30 months suggest a lifetime of ~19 years (and potentially up to 42 years). The ability to measure details of a young island's landscape evolution using satellite remote sensing has not previously been possible at these spatial and temporal resolutions. A new volcanic island in the southwestern Pacific Ocean was monitored via high‐resolution satellite imaging over ~30 months since its time of formation in early 2015. This island, unofficially named Hunga Tonga Hunga Ha'apai (HTHH), was not expected to persist as land for more than a few months, but our observations have documented its lifetime for at least 36 months. Using topography derived from high‐resolution satellite images, the above sea level volume of the island was measured over time, leading to a “volumetric” erosion rate that was compared with other oceanic islands. The HTHH island is disappearing much faster than Surtsey, but far slower than recent nearby activity indicates. Regional submarine topography shows that shallow‐water topology may be an important factor in explaining the unanticipated lifetime of this new island, together with internal strengthening by hydrothermal mineralization. The stages of erosion at the HTHH island may have implications for similar landforms discovered on Mars and their evolution in association with surface water levels. The range of plausible lifetimes for this Tonga island system ranges from about 19 to 42 years, at our measured current rates of erosion (0.0026 km3/year). Volumetric erosion for new hydromagmatic island is approximately 0.0026 km3/yearDemonstrated first meter‐scale documentation of landscapes and topography for a new volcanic island over its initial stages of erosional evolution (approximately 3 years)Satellite‐based measurements of new island predict lifetime of up to approximately 42 years |
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