Shake ’n quake
Does the Dominican Republic lie in an area of seismic activity?
An extensive seismological matrix of systems covering the entire island. The Seismological Institute of the Universidad Autonoma de Santo Domingo reports that there are around 90 earthquakes a month in the DR, most of which are not felt.
Does Santo Domingo lie on a fault line? Can an earthquake in another part of the island affect the city?
You may take some comfort in the fact that Santo Domingo does not lie directly on top of a fault, but this does not eliminate the possibility of seismic waves drastically affecting the city from a distant epicenter. This lesson was dramatically learned after the catastrophe in Mexico City in 1985. Seismic waves travelled 350 kms along the Pacific coast from Acapulco.
Since important knowledge have been attained from disasters in other parts of the globe, it is necessary to know the composition of the subsoil and how the structures built on it will withstand violent vertical and horizontal shaking. Santo Domingo is built extensively on a rock foundation which provides a great deal of stability. One of the most vulnerable regions of the island is the Cibao, because of the soft soil which is not compacted.
The seismic readings from micro-shocks give scientists sufficiently precise information to enable them to form a picture of the characteristics of a fault line; they do not all behave the same way, they have separate “personalities.” One fault may produce vibrations that can be felt while another, releasing the same energy, will not; one will produce a shake while another will give no such disturbance. From such data it is known, for example, that an earthquake in Ocoa, registering strength 5 on the Richter Scale, could devastate the city of Santo Domingo.
Which city is most at risk?
Earthquake expert, engineer Rafael Corominas explains that the city of Santiago is very vulnerable to earthquakes. He said that five kilometers from the city, the Caribbean and North American tectonic plates meet. The plate crosses the island entering by way of the Manzanillo Bay leaving through Samana province. Residents in this city should make sure their dwelling’s structure has been designed to resist the energy that could be generated in an earthquake.
Can an earthquake be predicted?
There are three categories. Regarding the long range prediction, the Seismological Institute, for instance, states with confidence that there will be a big earthquake within the next 25 years. The medium range prediction and the short range prediction can possibly be forecast the day before the likelihood of a movement from data recorded on the monitoring units installed at strategic points around the island. These are still unreliable, since with even the most sophisticated equipment it is not always possible to distinguish a precursor to an earthquake from a meaningless change in the Earth’s crust.
Although we may not be able to detect their approach with any certainty, we must prepare for their assaults. More and more emphasis is being placed on such preparedness—because no matter what, predictions do not prevent earthquakes.
When was the last major earthquake recorded in the Dominican Republic?
Tremors, which are earthquakes registering between one and four on the Richter Scale, occur on a regular basis and the public in general is quite oblivious to them. Shakes registering 6, 7, 8, or 9 are the cause for greatest concern. The last earthquake of catastrophic dimensions was in 1947, when the town of Matancitas in northeastern Nagua was destroyed. On March 7,1993, a shake in the municipality of Salinas and Cristóbal registered 5.2 and another on April 12, 1993 in the Cibao measured 5.7. These are enough to open cracks or fissures that can extend up to a kilometer in distance, causing structural damage to houses and roads.
An earthquake, measuring five points on the Richter scale, occurred in San Francisco de Macorís on June 10, 1993, with no material damage reported. The earthquake’s epicenter was located at the fault in the north central area of the town. Occurring at 9:35 pm and lasting 10 to 15 seconds, it was principally felt in San Francisco de Macorís, Santiago, Moca, Villa Altagracia, Pimentel, Cotuí and some areas of Santo Domingo.
Are there monitors detecting earth movement here in the D.R.?
Yes and no. Yes, there are 15 detection units strategically placed about the country, but at any one time as many as 12 may be out of action. These monitors relay information to the Institute where seismographs are constantly working. An earthquake could cause damage to one of the large reservoirs, releasing a potential water bomb.
What precautions can I take if there is no warning of an impending earthquake?
Discuss with your family members what measures will be taken and agree upon certain responsibilities to be divided between you—this adds up to “making plans.” Preparedness is stressed, over and over again. It could save your life.
- Walk through your house room by room making a mental note of where you could take cover.
- Put large heavy objects on lower shelves. Peg bookshelves and glass cupboards to the walls with strong nails.
- Move beds so that they are not directly under any windows or mirrors.
- Learn how to shut off the main sources of electricity, water, and gas and secure the gas tanks and water heaters to the walls because if they fall over, they could cause a fire.
- Keep a torch (flashlight) with spare batteries in a designated spot, e.g., bedside.
- Keep your exits clear of bicycles, boxes, furniture or anything blocking your exit.
- Store insurance policies, inventory lists, and any important documents or valuables in a safety deposit box or other such safe place.
- Know the basics of first aid and keep a first aid kit stocked and easily available.
What can I expect to see and feel during an earthquake?
Although the duration of a tremor is approximately one minute, it will be the longest 60 seconds of your life. The deafening noise is aggravated by objects crashing to the ground and house alarms tripping in. The ground will start to move softly at first becoming progressively more violent.
Where can I take cover during an earthquake?
Some people “freeze” in moments of extreme stress, but you must “react.” If you are in a public place, e.g., a restaurant, office etc. where there are a lot of people, resist the urge to run for the nearest exit. Keep calm, you do not want to be trampled in a stampede. Also, the elevator or stairs may have been damaged or the electrical supply knocked out. Duck under the nearest table or desk.
If you are at home, stay there. Do not run outside where you will be at a greater risk from flying debris or from falling and hurting yourself. Keep away from windows, glass doors, bookshelves, or anything that may fall over or break and therefore pose a serious threat. Again, take cover under a sturdy table, bed or in a small cupboard. If you are in an apartment, the area in front of the elevators is often windowless and can provide protection.
What do I do if I am outdoors when an earthquake hits?
Keep away from buildings, trees, and most important of all, electric cables that could arc and electrocute a person. If you are in a car, pull over and stop. Then lie down on the seats or in the seat well and cover your head to protect it against flying objects.
Is the beach a good place to be during an earthquake?
No. Get out of the water and get yourself to higher ground as soon as possible. Stay at least 300 meters from the edge of the shore. If there should be a seismic sea wave (tidal waves are very rare), it will cause waist-high surf.
What should I do after the earthquake?
Wait for a moment or two to make sure there will be no secondary tremors known as after-shocks. Although these are usually much less intense than the original, they can cause damage to already debilitated structures. Make a quick inspection to see if anyone is injured or trapped. Do not move anyone seriously hurt unless they are in imminent danger.
May I move about freely?
Yes, but be careful opening cupboards and closets as everything will have shifted position. Try to keep your curiosity in check and do not drive around your area to see the damage. Rescue vehicles will be having enough trouble getting through without unnecessary traffic on the roads. If you have a medical emergency, use the telephone if it still works, but otherwise try to leave the lines free.
What do I do if I smell gas?
Shut off the gas at the source, e.g., the cylinders, open the windows, and leave the building. Do not return until the gas has completely cleared and do not use gas powered apparatus until the system has been checked.
Will I be evacuated from my house?
The Civil Defense, the organization responsible for coordinating emergency response and assistance, will inform you if you are to evacuate a specific area. If you are in such an evacuation zone, do so promptly and take with you a radio, torch, first aid kit, important documents, money, food, and a sleeping bag, if you have one. It is a good idea to leave a note at your home indicating your temporary location.
Do the local building regulations call for special standards to counter the effects of earthquakes?
The objective is to prevent structures from collapsing, and thereby avoid loss of life, by building strengthening factors into the design. A building should be able to withstand the horizontal and vertical forces, resulting from the ground shaking violently during an earthquake. The typical residence in the Dominican Republic is made of concrete and eminently able to withstand such pressures. As a consequence, the special regulatory provisions only apply to buildings over four floors.
Earthquake expert, engineer Rafael Corominas explains that the city of Santiago is very vulnerable to earthquakes. He said that five kilometers from the city, the Caribbean and North American tectonic plates meet. The plate crosses the island entering by way of the Manzanillo Bay leaving through Samana province.