U.S. and B.C. officials say there is no tsunami threat for British Columbia after a 7.5-magnitude earthquake struck in the Pacific Ocean, near the Alaska Peninsula Coast.
According to the United States Geological Survey, an earthquake with a magnitude 7.5 occurred 91 kilometres southeast of Sand Point Alaska at 1:55 p.m. PDT, with a depth of 40.1 kilometres. There were several reports of the earthquake being felt.
A 7.5-magnitude earthquake near the Alaska Peninsula on Oct. 19, 2020 (USGS)
According to the U.S. Tsunami Warning System, run by the U.S. National Oceanic and Atmospheric Administration (NOAA) and the U.S. National Weather Service (NWS), a tsunami warning was in effect for South Alaska and the Alaska Peninsula: Pacific coasts from Kennedy Entrance, Alaska (64 km southwest of Homer) to Unimak Pass, Alaska (128 km northeast of Unalaska).
By 4:06 p.m. PDT, the warning was downgraded to an advisory.
The tsunami threat for B.C. had been under evaluation but by 3:39 PDT, the National Weather Service’s National Tsunami Warning Center in Palmer, Alaska said “for other U.S. and Canadian Pacific coasts in North America, there is no tsunami threat.
Emergency Management BC confirmed shortly after there was no tsunami threat for British Columbia.
The Port Alberni Fire Department had said they were aware of the earthquake and possibility of a tsunami, noting the epicentre is 2,000 kilometres away from North Vancouver Island.
The fire department said if the Island was to be impacted, it would not have been for a number of hours.
We are aware of the earthquake & possibility of a tsunami. Epicentre is 2K km away from the North V. Isle. If V. Isle were to be impacted it would not be for a number of hrs as indicated on the attached map. Standby for further updates. No action required at this time. #tsunami https://t.co/DmNs6TR7eA
— Port Alberni Fire (@portalbernifire) October 19, 2020
Attached is a map of the current Tsunami Warning. The risk to British Columbia continues to be evaluated. #tsunami #earthquake #alaska #britishcolumbia pic.twitter.com/iMFR4rPl18
— Port Alberni Fire (@portalbernifire) October 19, 2020
There was a small tsunami in the Alaska area after the earthquake, with tsunami activity observed at Sand Point, Alaska at 4:11 p.m. PDT, with a maximum tsunami height (the highest recorded water level above the tide level) at 2.3 feet (0.7 metres).
There was also tsunami activity at
- King Cove, Alaska at 4:36 p.m. PDT, maximum height 2.1 ft (0.6 m)
- Nikolski, Alaska 4:37 p.m. PDT, maximum height 0.3 ft (0.09 m)
- Unalaska, Alaska 5:58 p.m. PDT maximum height 0.3 ft (0.09 m)
- Atka, Alaska 4:52 p.m. PDT 0.2 ft (0.06 m)
- Chignik Bay, Alaska 6:26 PDT 2.5 ft (2.5 m)
Tue Oct 20 00:37:37 UTC 2020 event picture pic.twitter.com/WqyrnzQxCy
— NWS Tsunami Alerts (@NWS_NTWC) October 20, 2020
The NOAA and NWS said people who are in a tsunami warning area need to:
- Evacuate inland or to higher ground above and beyond designated tsunami hazard zones or move to an upper floor of a multi-story building depending on your situation.
- Move out of the water, off the beach, and away from harbours, marinas, breakwaters, bays and inlets.
- Be alert to and follow instructions from your local emergency officials because they may have more detailed or specific information for your location.
- If you feel a strong earthquake or extended ground rolling take immediate protective actions such as moving inland and/or uphill preferably by foot.
- Boat operators, where time and conditions permit, move your boat out to sea to a depth of at least 180 feet (54 metres).
- If at sea avoid entering shallow water, harbours, marinas, bays, and inlets to avoid floating and submerged debris and strong currents.
- Do not go to the shore to observe the tsunami.
- Do not return to the coast until local emergency officials indicate it is safe to do so.
Impacts:
If you are in a tsunami warning area;
- A tsunami with damaging waves and powerful currents is
possible. - Repeated coastal flooding is possible as waves arrive onshore, move inland, and drain back into the ocean.
- Strong and unusual waves, currents and inland flooding can drown or injure people and weaken or destroy structures on land and in water.
- Water filled with floating or submerged debris that can injure or kill people and weaken or destroy buildings and bridges is possible.
- Strong and unusual currents and waves in harbours, marinas, bays, and inlets may be especially destructive.
- Some impacts may continue for many hours to days after arrival of the first wave.
- The first wave may not be the largest so later waves may be larger.
- Each wave may last five to 45 minutes as a wave encroaches and recedes.
- Coasts facing all directions are threatened because the waves can wrap around islands and headlands and into bays.
- Strong shaking or rolling of the ground indicates an earthquake has occurred and a tsunami may be imminent.
- A rapidly receding or receded shoreline, unusual waves and sounds, and strong currents are signs of a tsunami.
- The tsunami may appear as water moving rapidly out to sea, a gentle rising tide like flood with no breaking wave, as a series of breaking waves, or a frothy wall of water.
Alexa Huffman
