The earthquake phenomenon in the St. Thomas/ St. John region is a case of good news and bad news. The bad news is the fact we do have some 30 to 40 tremors (measurable events) a month and can expect a big one at any time. The good news is, we appear to be moving upward.
For several decades, Californians have been subjected to the theory there will be a great seismic event, which will split off a good segment of the western coastal states and drop it into the Pacific Ocean. The Santa Barbara Channel islands of Catalina, Santa Cruz, Santa Rosa, and San Nicholas are results of a major seismic event which moved them away from the rest of California dropping a chunk of land into what is now the Santa Barbara Channel. This structure, a down fallen block is know by geologists as a "graben."
In the case of Puerto Rico, St. Thomas, St. John, and the British Virgins; we appear to be rising out of the sea. This movement is brought about by South America moving closer to North America. As these two giants move together, the Caribbean Plate is being pushed out into the Atlantic like a blob of toothpaste.
It appears the northern edge of the Plate is rising as it rides over the North American Plate. The Antilles Chain, on the other hand, is volcanic in nature. Apparently as the Caribbean Plate rides over the submerged Atlantic Plate, material is forced into the earth's core (magma), where it melts and seeks release through the tender zone at the edge of the intruding Caribbean Plate. This causes volcanoes, which continue to form the eastern Caribbean islands today. Examples include the current activity at Montserrat and the underground volcano called "Kick em Jenny" off the coast of Granada.
Now that we know that earthquakes are always happening and that the time may come when it is a disastrous event, we can plan to cope. The first thing to do is to develop a family plan, especially where to meet following a sudden disaster. If everyone now where to go, the stress of lost family and wasted energy looking is mitigated.
Second, secure heavy objects that could fall down injuring people and causing unnecessary damage. This is especially important with high bookcases and propane gas cylinders.
Third, secure breakable items on shelves. A piece of fishing line, weed eater line, wire, whatever to keep items from slipping off shelves.
Finally, secure any item that might fall onto the floor and be damaged such as radios, TVs, cable boxes, microwaves, etc.
We could go another 100 years without an event of any magnitude, or it could hit tonight. How well your family will survive depends on your ability to plan ahead based on your understanding of the dangers you face.
Editors' note: Kirk Grybowski is a graduate geological engineer who served two years as Director of the Virgin Islands Territorial Emergency Management Agency.
