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Do earthquakes swarm? April 12, 2008

Posted by eyegillian in environment, explore, learn, life, nature, science, world.
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Swarm of Bees poster by Malcolm Warrington

It’s not every day that you read about a “swarm” of earthquakes. Yet the story about a swarm of hundreds of earthquakes off the Oregon coast is all over the news this morning.

According to the Oxford dictionary, a swarm is a large number or dense group of insects, birds, small animals, persons, etc., moving about in a cluster; when referring to bees, it means to congregate in large numbers; when referring to a place: be overrun, be crowded, abound…

A word like “cluster” would have seemed more accurate to me. “Swarm” sounds like a negative term, a warning that Westcoasters are about to be overrun by a swarm of earthquakes.

And maybe they are. Geophysicists have reported 600 earthquakes in 10 days in a basin 320 kilometres southwest of Newport, near the Juan de Fuca fault. One quake was as big as magnitude 5.4.

More unusual, however, is the sound of these earthquakes. Scientists have been listening in on underwater life for 17 years, using hydrophones (underwater microphones) — placed by the navy to listen for submarines during the Cold War — and they’ve never heard anything like this. What do underwater earthquakes sound like? Thunder.

underwater volcanic vent

I’m wondering if the earthquakes are caused by a new hyperthermal vent system, like the one in the photo to the right.

A story earlier this year noted how a team of seismologists have been studying these vent systems, working under 2,500 meters of water on the East Pacific Rise, some 565 miles southwest of Acapulco, Mexico. They planted seismometers around an ocean ridge to record tiny, shallow earthquakes — in this study, 7,000 of them, over 7 months in 2003 and 2004.

The researchers interpret the quakes as the result of cold water passing through hot rocks and picking up their heat, a process that shrinks the rocks, and cracks them, creating the small quakes.

If these hyperthermal vents are the source, maybe the news reports should be referring to a “burp” or a “rumble” of earthquakes. I am tempted to use “explosion” of earthquakes, but I hope it doesn’t come to that.

Speaking of collective nouns, does anyone have a good suggestion for a group of bloggers? One suggestion here is a “waffle” of bloggers. Any other ideas?

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Related Links:
CBC: “Scientists baffled by unusual swarm of hundreds of quakes of the Oregon coast”
Science Daily: “Earthquakes under Pacific floor reveal unexpected circulatory system”
National Geographic: “Swarm Behaviour”
Collective Nouns

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Comments»

1. lavenderbay - April 12, 2008

The people on my blogroll feel to me like a small group of friends, gathered around a virtual cafe table, so I would like to offer the expression “a klatsch of bloggers” to describe a friendly sub-community of the blogosphere.

2. eyegillian - April 12, 2008

Thanks, Lavenderbay,I really like your suggestion. “Klatsch” has a lovely scent of coffee and cafe and cosy about it.

3. 88mileshome - April 13, 2008

How about a ‘teem’ of bloggers? Not meant to be a pun on team, I just love the sense I get on WordPress and in other blogging communities – being part of a busy hub of writers, all buzzing and teeming with ideas.

4. eyegillian - April 13, 2008

Great suggestion, 88mileshome — the way you describe “teem” sounds almost like a “swarm” of bees, except it’s much more friendly!


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