A strong earthquake struck Alaska’s Aleutian Islands on Thursday morning, with the U.S. Geological Survey later listing the event at a preliminary magnitude of 6.5.
The quake was centered about 165 kilometers west of Nikolski on Umnak Island, according to the USGS. It was not immediately clear whether the earthquake caused injuries or damage, and officials said there was no immediate tsunami threat.
The September 17 earthquake was reported shortly after it occurred, with early information focusing on its magnitude, depth and location west of Nikolski. As more seismic data became available, the reported magnitude changed from the initial figure carried by some news organizations.
Early reports placed the earthquake at magnitude 6.3. The Jerusalem Post, citing Reuters and the USGS, reported that figure shortly after the quake and said it occurred at a depth of 83 kilometers, or about 51.6 miles. Later reporting listed the magnitude at 6.5, reflecting an updated preliminary estimate.
No immediate tsunami threat
The National Tsunami Warning Center said there was no immediate tsunami threat following the earthquake, according to USA TODAY.
Initial reports also did not identify any confirmed injuries or structural damage. The available information remained limited in the hours after the quake, with the USGS providing the main technical details about the event.
The earthquake’s location placed its epicenter well west of Nikolski, in the Aleutian Islands. USA TODAY described the event as a significant earthquake and noted that the magnitude was preliminary, meaning the reported strength could still be adjusted as additional seismic data was reviewed.
Earthquake strength put in context
USA TODAY also included a general breakdown of earthquake magnitudes, citing information from Michigan Technological University. Under that scale, earthquakes between magnitude 6.1 and 6.9 can cause serious damage, while events between 5.5 and 6.0 may cause slight damage to buildings.
Stronger earthquakes in the 7.0 to 7.9 range are classified as major and can cause serious damage, while earthquakes of magnitude 8.0 or higher can be massive and capable of destroying communities. Those categories describe the potential effects associated with different magnitudes and do not mean comparable damage occurred in Thursday’s Alaska earthquake.
The key early indicators after the Aleutian Islands quake remained reassuring: no immediate tsunami threat was announced, and no injuries or damage had been confirmed in the first reports.
The event nevertheless drew attention because of its strength and the revision from the initially reported magnitude of 6.3 to 6.5. The USGS event page carried the continuing record of the earthquake as seismic data was reviewed.
