At 9:51 AM local time on September 25, 2014, a magnitude 6.2 earthquake hit Alaska about 95 km WNW of Willow, Alaska. This earthquake caused moderate to strong shaking in Anchorage, Alaska and many other surrounding cities. Although the earthquake seems to have caused significant shaking near the epicenter, no fatalities have been reported and the damage seems to be minimal with reports of objects rattling and falling off shelves, but no other major damage to buildings and other structures.
This earthquake serves as a reminder to the Great Alaskan earthquake in 1964, a magnitude 9.2 earthquake that shook Anchorage and other parts of Alaska as the second largest earthquake in recent history. A magnitude 9.2 earthquake is 31,622 times stronger (energy release) than a magnitude 6.2 earthquake. Earthquakes are typically judged based on the Richter Scale, in which the amplitude of the wave created by the earthquake is measured by a seismometer and put through a formula to rank the quake in terms of intensity. Another less scientific method of ranking earthquake intensity and magnitude is the Mercalli Scale, in which the observations and reactions of people who experienced the earthquake first-hand are gathered and used to rank the earthquake based on the damage. This method is not considered an accurate reflection of earthquake magnitude, size, or strength because of the margin for human error. See below for a chart of the Mercalli Scale.
Earthquakes in Alaska are frequent because of the convergent plate boundary between the Pacific and North American plates. The dense oceanic plate is subducted beneath the less-dense continental plate. The boundary runs along the southern portion of Alaska and along the Aleutian islands creating frequent tectonic activity such as earthquakes and volcanic eruptions. For more information on subduction and convergent plate boundaries, see the IRIS video below.
This earthquake is a reminder to all to be prepared in the event of an earthquake. The Great ShakeOut earthquake drill event is an opportunity for all to be prepared, and is coming up in the month of October. The EarthScope National Office is involved with this event and encourages all to register online and participate in the drill. For more information about the ShakeOut, visit the ShakeOut website.
For more information about Earthquakes in Alaska, visit the Alaska Earthquake Center.