The Recent Earthquakes map issued by the University of Alaska’s (UA) Geophysical Institute is marked with 90 square boxes, several of them overlapping one another, in hues of white, yellow, orange and red. Each color-coded square marks an earthquake recorded in the state. The current map is tracking tremors from a starting point of January 12, and notes the time frame between quakes with a color legend. Red indicates quakes within the last hour; orange for quakes occurring within the last 12 hours; yellow for quakes recorded during the past day; and white for quakes a day old.
Tracking the Alaskan quakes hour by hour
The most recent recorded quake was at 4:22am local time in the Andreanof Islands, some 1700 miles west of the state capital, Juneau. Recorded at a magnitude of 2.52, this area also experienced a quake of unknown magnitude at 12:33 this morning (2011 January 15).
Today’s earthquakes began at 12:05am with M~ 2.68 shake in the Cook Inlet region. Seven quakes followed, each about an hour apart. The most severe was in the Rat Islands, recorded at 4:16am with M~ 4.06.
At 3:27am local time, a minor earthquake was located ten miles west of Anchorage and nearly 600 miles away from Juneau. This small shake was magnitude 1.79. An hour and fifteen minutes earlier, another tremor of unknown magnitude was recorded in the Yakutat Bay region, 271 miles WNW of Juneau.
First quake near Trans Alaska Pipeline pump stations
The first earthquake reported during this four-day period occurred 14 miles northeast of Fairbanks on January 12. The UA map information gave no record of the magnitude. However, the quake was within 120 miles or less of five pump stations associated with the Trans Alaska Pipeline System or TAPS, operated by Alyeska Pipeline. These included Pump Stations 6, 7, 8, 9 and 10.
According to Alyeska, pump stations 6, 8 and 10 have been in “standby” mode for a number of years. Pump stations 7, 9 and 10 are apparently operational. Alyeska also states that the pipeline is able to withstand a maximum 8.5 Richter Scale earthquake at the Denali Fault. However, that range varies from 5.5 to 8.5 in other areas of the 800-mile pipeline. In 2002, a severe 7.9 earthquake shook the interior region of Alaska near the Denali Fault, just 50 miles from the pipeline. According to the Alyeska Pipeline Factbook, this was the largest earthquake on the Denali fault in 90 years, and the pipeline held.
More recently, Pump Station 1 was shut down for four days after a leak was discovered in the Booster Pump Room basement on the morning of January 8, 2011. The oil leakage emanated from underground piping encased in cement. This is the northernmost pump station, located on Alaska’s North Slope.
Severity of earthquakes
About 70 of the recent earthquakes fall below the 3.0 intensity, which means they have likely not been felt except by a very few people. Four are at the higher end of the scale, falling within 3.0 to 3.9 in intensity. Only one quake has exceeded magnitude 4.0 in intensity. At this level, according to the U.S. Geological Survey, the repercussions would be felt by many indoors during daylight, and a few during night. Dishes, doors and walls could be disturbed. The effect of the quake would be similar to a heavy truck hitting a building.
One of the first quakes, on January 12, measured M~3.86. However, it was situated underneath the Gulf of Alaska. Another earthquake with the same magnitude occurred Friday, January 14, about 85 miles southeast of Mt. Rechesno in the Fox Islands.
The most severe earthquake recorded occurred this morning in the Rat Islands. A 4.06 magnitude quake hit this earthquake-prone, uninhabited spot in the Aleutian island chain.
Earthquake damage and destruction occurs when the quake tops the 6.0 scale.
Sources
Alaska Earthquake Information Center, Geophysical Institute, University of Alaska. 2011. Recent Earthquakes.
Alyeska Pipeline. 2008. Pipeline Facts: Pump Stations.
Trans Alaska Pipeline System Facts. 2009. “Earthquake”.
U.S. Geological Survey, Department of the Interior. 2010. Magnitude/Intensity Comparison.
Join the Conversation