…shake, but don’t get rattled

Last week was Earthquake Awareness Week in Jamaica.  In this week the Government and the Office of Disaster Preparedness and Emergency Management (ODPEM) published information and held meetings about how to be safer before an earthquake and what to do if a quake happens.  They also conducted tests of emergency services to make sure that help could come quickly and effectively if a disaster struck.

A lot of this effort seems to have been wasted on people who saw the news material and meeting notices, said, “Oh, that again” and went on their way thinking “It can’t happen here.”  But last week also marked the first anniversary of the quake that cause so much destruction and suffering in Haiti.  That should have been a grim reminder that it can happen here, and it only takes one quake to cause a lot of misery.

The Caribbean is a very active region with three live volcanoes and well over a thousand earthquakes every year, though most of them are too small to feel.  The “hot corner” between the Dominican Republic and the Virgin Islands averages more than a dozen measurable quakes every week.

Jamaica, according to UWI Mona’s Seismic Unit, records at least 200 earthquakes annually.  The most active zones are in the Blue Mountains and the Montpelier-Newmarket area, but small shocks have been recorded all over the island.  The most recent that was big enough to feel happened on December 8, near Mile Gully in Manchester.  It measured 3.8 on the Richter Scale (see chart) and was felt in parts of Manchester, St. Elizabeth and Clarendon.

Why should Jamaica be recording three or four earthquakes a week?  The answer lies in “plate tectonics” – the science of how the floating chunks of the earth’s crust move, and what happens when they rub against each other.

The layout of the plates in our area is more complicated than it looks on the big maps.  Most of these show the Caribbean Plate squeezed like a knee-cap between the North American Plate (ending just south of Cuba) and the South American Plate (just north of Venezuela).  A long sliver, the Gonave Micro-plate, is breaking away like a bone chip from the north edge of the Caribbean Plate.  Jamaica sits at the bottom of this micro-plate, about half-way along.

The North American Plate is moving west and the Caribbean Plate is moving (more slowly) eastward.  Their combined drift adds up to about an inch a year.  The micro-plate containing Jamaica is along for the ride, and it’s a bumpy one.  When friction stops a section of the plate edge from moving, a lot of momentum builds up.  Sooner or later, the “stuck” spot lets go, and the released energy shakes everything around it.

We can’t predict earthquakes very well, and we can’t stop them from happening.  We can be prepared.  Most of the preparation is just common sense, and is also useful protection against damage and injury from hurricanes and floods.  If your home is in good repair, your yard is tidy, and big dangerous things like gas cylinders, stoves and refrigerators are securely held in place, you’re about as ready for an earthquake as it’s possible to be.  Pick out a safe spot to go – for earthquakes, usually a bathroom or a sturdy doorway -- and make sure your family has a plan for any emergency.  A little preparation now can save a lot of misery later.