Features and deposits on Bogoslof Island after the eruptive events of January 30-31, 2017. Shallow groundwater flow through the new volcanic deposits from the sea toward the center depression has resulted in the formation of concentric headscarps and channels. This process, called sapping, is common in areas of concentrated groundwater discharge where it undermines slopes and leads to headward erosion and the formation of arcuate headscarps. Rubbly appearing rock debris scattered over parts of the island was likely generated by near surface explosions of a still submarine lava plug, showering the island with blocks and bombs of rock debris. Some of these rock fragments are up to 2.5 m in length. The mound of tephra on the southern part of the island is a tuff cone, and the level area making up the northern half of the island is a tuff ring. These are characteristic landforms of shallow submarine eruptions. The Bogoslof Island landscape is susceptible to rapid erosion, primarily by ocean waves, and erosion of the surficial volcanic deposits will be ongoing and changes in the configuration of the island are likely. ©2017 Digital Globe NextView License. Base image Worldview-3, 1/31/2017.
Image courtesy of AVO/USGS.
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