4 earthquakes – with one measuring M5.7 – hit within an hour off Little Sitkin Island, Alaska, on which sits two giant calderas and an active stratovolcano, on April 27, 2017.
Could this series of quakes indicate the next big eruption on the island?
The following four earthquakes hit, within 1 hour, off Little Sitkin Island, Alaska, almost at the same place:
M 5.7 – 77km S of Little Sitkin Island, Alaska
M 3.2 – 122km SSE of Little Sitkin Island, Alaska
M 4.2 – 76km S of Little Sitkin Island, Alaska
M 3.9 – 85km S of Little Sitkin Island, Alaska
Here is what the Alaska Volcano Observatory (AVO) reports about this volcanic island: “The active stratovolcano on Little Sitkin Island occurs within the eroded remnants of a nested double caldera of probable late Pleistocene age. The older caldera (Caldera One) is about 4.8 km in diameter and is centered slightly northeast of the island’s midpoint. The caldera formed at the site of a large stratovolcano, the remnants of which are the oldest rocks exposed on the island.
A second stratovolcano was constructed almost entirely of lava flows within Caldera One and attained a height of about 900 m. A cataclysmic eruption, possibly in early post-glacial time, resulted in the formation of a second, smaller caldera (Caldera Two) that partially destroyed this cone. Caldera Two is elliptical in outline and measures 2.7 by 4 km; the inferred eastern and southern margins are coincident with those of Caldera One.
SO ARE WE ASSISTING TO AN AWAKENING OF THIS GIANT CALDERA?
