ANCHORAGE, Alaska — The Alaska Volcano Observatory is keeping an eye on a western Aleutians Island volcano that last erupted in 1987.
The observatory has upgraded the alert level to "advisory" for Semisopochnoi (sem-is-SOH'-pahk-noy) Volcano, indicating it's exhibiting signs of elevated unrest above known background levels.
The volcano is 2,625 feet high. It's on an uninhabited island 40 miles northeast of Amchitka (am-CHIT-ka) Island and about 1,300 miles southwest of Anchorage.
The observatory says earthquake activity picked up in January and has increased in the last few days.
The observatory has detected brief periods of seismic tremor, which can indicate movement of magma or magma gases.