( CNN ) -- Researchers have raised the alert status at Mount Redoubt , a volcano in southern Alaska , after another increase in seismic activity . Seismic activity at Alaska 's Mount Redoubt again has scientists watching for an eruption . `` Shallow earthquake activity under the volcano has been as high as 26 events per 10-minute period , '' officials at the Alaska Volcano Observatory said Sunday in a statement announcing that the alert level was raised to `` watch '' status . Although no eruption has occurred , the scientists said the increase in seismic activity `` likely represents either the upward movement of magma or pressurization of the system . '' `` It is possible for unrest at the volcano to change rapidly , and seismic activity or other signs of unrest could escalate culminating in an eruption within days to weeks , '' the statement concluded . An increase in seismic activity at the same volcano prompted a `` watch '' level last Monday . In the U.S. Geological Survey 's color-coded alert levels , the orange `` watch '' level means the volcano `` is exhibiting heightened or escalating unrest with increased potential of eruption '' or that `` eruption is underway with no or minor volcanic-ash emissions . '' The next level is red , meaning an eruption is imminent or underway . Bill Burton , a geologist with the U.S. Geological Survey , said since January there have been increases in seismic activity at Mount Redoubt followed by periods of quiet . The 10,197-foot peak is about 100 miles southwest of Anchorage , the most populous city in Alaska . Mount Redoubt last erupted nearly 20 years ago , in December 1989 . That eruption lasted until April 1990 .
Increase in seismic activity noted at Mount Redoubt in southern Alaska . Alert level raised ; `` eruption within days to weeks '' is possible , officials say . Volcano last erupted in December 1989 and last for months . Mount Redoubt is about 100 southwest of Anchorage , Alaska .