An earthquake measuring 7.5-magnitude stuck an area off the southern coast of Alaska in the Pacific Ocean early Saturday morning at 3:58 EST, immediately prompting tsunami warnings and advisories down the Alaskan coast and Canada's.
The earthquake, with a depth of 5.5 miles (9 kms), had its epicenter 63 miles (103 kms) west of Craig, a town on Prince of Wales Island in Alaska. It was located 208 miles south of the Alaskan capital, Juneau, the United States Geological Survey (USGS) said Saturday.
Initially, the size of the Alaskan temblor was given as 7.7, but later it was downgraded to a 7.5-magnitude by USGS. The earthquake readings are based on the open-ended Moment Magnitude scale used by US seismologists. This scale measures the area of the fault that ruptures and calculates the total energy released.
There were no immediate reports of casualties or damage caused by the earthquake. The West Coast and Alaska Tsunami Warning Center said a small tsunami of roughly six inches was generated by the quake close to Port Alexander, a southeastern Alaskan town on Baranof Island.
Officials said a tsunami warning was canceled for parts of British Columbia, Canada, and southeastern Alaska. A tsunami watch for the coastal areas of the British Columbia-Washington border was also revoked.
The US tsunami warning center issued a statement saying: "Sea level readings indicate a tsunami was generated. It may have been destructive along coasts near the earthquake epicenter."
Based on available data, the tsunami center also clarified there was "no destructive threat" of a tsunami to Hawaii and other coastal areas in Pacific. But, warned that those coastal areas could experience “small non-destructive sea-level changes lasting up to several hours."
According to the Juneau Empire newspaper, homes were rattled in the Alaskan state capital some 205 miles (330 kilometers) away. Fortunately, there were no obvious major damages caused in the city, the largest in the area. Speaking to the Empire, Juneau resident Archie Hinman said the quake "shook my Juneau home violently enough to awaken the entire family. (But there was) no apparent damage."
Tsunamis are formed when a massive earthquake causes a sudden rise or fall in the sea floor, which in turn triggers rapid displacement of large quantities of water. The recent 7.5 magnitude Alaskan earthquake and subsequent tsunami warnings must have surely caused panic among the local residents, conjuring visions of the horrific destruction wrought on the hapless humanity by the devastating earthquake-cum-tsunami in Japan in March 2011, which killed thousands.
Alaska residents fears would not be unjustified as just last October , a 7.7-magnitude earthquake hit British Columbia’s Queen Charlotte Islands, located just south of the present epicenter of the earthquake. It triggered a tsunami that spawned all the way to Hawaii. Then sirens were sounded to warn residents to reach higher ground.
While the warning given was that the waves surge could be between three and six feet, they proved to be smaller and less powerful than feared. The largest wave measured was in Kahului, on the island of Maui. It was about 2.5 feet above sea level. Fortunately, there was no damaged caused to the islanders.
In 1964, a gigantic earthquake measuring a magnitude of 9.2 hit the coast of Alaska. It generated a wall of water more than 40 feet high that spawned across Alaska, British Columbia, Oregon and parts of California. 130 people lost their lives, with destruction of property running into millions of dollars.
According to geologists, an even bigger tsunami that was triggered by the 1964 earthquake could one day be in store for the West Coast. This is according to one analysis of sedimentation carried along the Gulf of Alaska coast. It would, therefore, behoove the local residents to take all necessary precautions.
Other miscellaneous news: