On São Miguel Island in the Azores, lava balloons are considered to be one of the main volcanic hazards stemming from submarine volcanic eruptions. Early lava balloons erupted during the 2011–2012 El Hierro eruption contained xeno-pumice, which raised concerns that evolved magmas such as phonolite and trachyte, capable of generating explosive eruptions, might be present under the volcano. As the eruption continued, these concerns together with an outburst of gas led to the evacuation of the town of La Restinga. The link between xeno-pumice and evolved magmas was contested early on; when explosive eruptions did not occur, this led to complaints that the response to the eruption had been disproportionate especially given its effect on the economy. The management of the El Hierro eruption in general attracted intense criticism.
