Published: 29th Oct, 2019
Scientists have discovered an earthquake-like event “stormquake” that can happen during a hurricane or other powerful ocean storms.
Context:
Scientists have discovered an earthquake-like event “stormquake” that can happen during a hurricane or other powerful ocean storms.
What is a stormquake?
- It is a new geophysical phenomenon entirely unknown to science - a hybrid entity where powerful storms such as hurricanes trigger seismic episodes that can rumble for hours or even days.
- Storms trigger giant waves in the sea, which cause another type of wave. These secondary waves then interact with the seafloor only in certain places and that causes the shaking.
- Stormquakes are limited to places along the edge of continental shelves or on ocean banks.
- "Earth's hum': It Is a phenomenon in which the constant sloshing of ocean waves produces seismic signals at frequencies of about once every few minutes.
- Microseisms: These are high-frequency signals created by ocean waves which occur every five seconds.
- Seismic noise is a band of signals generated in the ocean that occur once every 20 to 50 seconds or so or at a frequency of between 0.02 and 0.05 hertz.
- Stormquakes frequently occur in the Maritimes and Labrador Sea in the North American margin.
When is a stormquake generated?
To be a stormquake the source of the seismic data had to meet several criteria:
It had to occur during a stormy day.
It should not to be a part of known earthquake event and belong to a swarm of similar quakes on the same day.
Stormquakes are confined to certain regions along the coast where seafloor topography has small raised regions called ocean banks.
Examples of stormquake:
Hurricane Bill, a storm that formed 10 years ago in the Atlantic Ocean. Bill strengthened into a Category 4 hurricane before weakening to a tropical storm and hitting Newfoundland. This storm caused "numerous seismic events “off the northeast U.S. and Canadian coasts. As Bill approached several stormquakes located offshore New England and Nova Scotia were detected and caused continent-wide ground motions that lasted for about 30 hours.
Hurricane Ike (2008) and Hurricane Irene (2011) which led to stormquake activity in the Gulf of Mexico, while Irene caused seismic events off the coast of southern Florida.
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