Earthquake

What is an earthquake?

An earthquake is a natural hazard which occurs when the ground shakes or rocks violently. An earthquake can take place at any time, day or night, without any forewarning at all and is capable of inflicting the same type of damage as a major hurricane. This makes it the most unpredictable and feared of all natural disasters.

How Earthquakes Occur?

The earth is made up of four major layers: the inner core, outer core, mantle and crust. The crust is the outermost and thinnest layer of the earth made out of rock. This layer of rock is not one smooth continuous layer In fact, the rock is broken into several large pieces that can fit together like a jigsaw puzzle (Figure 1). These pieces are known as tectonic plates.

Include imagery with types of tectonic plates similar to this

These tectonic plates are able to move around and interact with one another; sliding and bumping into each other. When two or more of these plates meet, they can lock or stick together, similar to when your fingers interlock with each other. The plates continue to move about trying to get themselves unstuck from one another and this causes energy to build up below the plates.

When the plates are able to break free from each other, the built up energy is released moving through the Earth resulting in the shaking of the ground or what we call an earthquake. The region where two or more plates meet is known as a plate boundary. An earthquake typically lasts under one (1) minute or sixty (60) seconds, but the shaking could be so violent at times to cause irreparable damage. When an earthquake first takes place, it is known as the main event. However, there may be a series of smaller earthquakes that could occur after the main one. These smaller earthquakes are known as the aftershocks and are capable of inflicting further damage. The aftershock is just as unpredictable as the main one.

How are earthquakes measured?

Scientists who study earthquakes (called seismologists) are NOT able to predict the exact time and location that an earthquake would strike. However, they are able to measure the magnitude of an earthquake or the amount of energy that is released from the earth when an earthquake takes place. Seismometers are used to record the seismic waves generated by an earthquake. Seismologists are then able to use these recordings to determine where the earthquake was located and how strong it was. Seismic waves may also be used to map the interior of the earth.

Magnitude is used to measure an earthquake’s size (usually on a Richter Scale) and is related to the amount of energy generated by the earthquake. The Mercalli Intensity Scale is used to categorise the levels of shaking observed during an earthquake.

Some significant earthquakes that have affected Trinidad and Tobago

2022 (July 17) – 5.8 magnitude earthquake was felt in Trinidad. No reported injuries
2020 (August 26)- A magnitude 5.0 earthquake occurred 34.7 km (21.6 mi) NW of Güiria, Venezuela; 113.3 km (70.4 mi) W of Port of Spain, Trinidad and Tobago and 115.5 km NW of Point Fortin, Trinidad and Tobago. The epicentre of the event was located at 10.767°N, 62.550°W, and at a depth of 91.7 km.
2018 (August 21) – A magnitude 6.9 earthquake occurred and reportedly lasted for about two minutes. A magnitude 6.0 aftershock occurred August 22, 2018. Further to the earthquake event there were 32 aftershocks. These were evenly distributed from 21st August 2018 into 22nd August 2018. There were no reports of loss of life and serious injury.
2010 (Dec 26) – A 4.7 magnitude earthquake was felt throughout Trinidad, from Carenage to Moruga to Matura. No reported injuries or damages.
2009 – 4.8 magnitude earthquake occurred on land and felt in Sangre Grande and Penal, no reported injuries.
2008 – 5.6 magnitude earthquake located on the East Coast and felt mainly in Galeota, no reported injuries.
2007 – 7.3 magnitude earthquake was felt throughout the Eastern Caribbean from Puerto Rico to Guyana; damage reported in Martinique, St. Lucia, St. Vincent and Barbados. This is the fifth earthquake in the magnitude 7 range to occur near Martinique since 1727.
2006 – 5.8 magnitude earthquake was felt throughout Trinidad with 3 reported injuries in Point Lisas.
1997 (April 22) – 6.1 magnitude earthquake occurred. US # 25 million in damages to Tobago, 2 were injured and 15 were left homeless.
1996 – 5.2 magnitude earthquake occurred North of Trinidad occurred New Year’s Day. No reported injuries.
1988 – 6.3 magnitude earthquake occurred off east Coast Trinidad. No injuries reported.
1982 – 5.2 magnitude earthquake was recorded as largest earthquake near Tobago up to that time.
1968 – 7.0 magnitude earthquake was reported with significant damage occurring in Venezuela with some damages to Port of Spain, Trinidad.
1954 – 6.5 magnitude earthquake occurred with one person being killed and many were injured.
1888 – 7.5 magnitude earthquake was reported. Damage occurred from Trinidad to St. Vincent.
1766 – 7.9 magnitude earthquake destroyed Trinidad’s then capital San Jose.

Before, After and During an Earthquake


*WHAT SHOULD I DO BEFORE AN EARTHQUAKE*	*WHAT SHOULD I DO DURING AN EARTHQUAKE?*	*WHAT SHOULD I DO AFTER AN EARTHQUAKE?*
● Build your home in accordance with the recommended building codes. See your local disaster management office for details.	If you are inside during the quake, your first order of business should be to protect your head from falling objects. Look around you for loose materials and try to move outside to a natural area free from debris or dangers. DROP – under something sturdy (desk or table). COVER – the back of your head and neck with your arms to protect yourself from falling debris. HOLD ON – to any sturdy covering so you can move until the shaking stops. – Stay where you are until the shaking stops and do not run outside! – Do not get in a doorway. – Help those who are injured or trapped and get them to safety.	Once the shaking stops, determine if you are in a safe area. If you are not, look for a clear path to safety. ● If you are in a building, determine if the building is damaged. If the building is damaged, evacuate and head for an open space away from damaged areas. ● Use stairs to exit buildings or structures. Do not use elevators. ● If you are trapped, do not move around and kick up dust. i. If possible, attempt to call for help with a cell phone. ii. Tap on a pipeline or walls to alert others of your whereabouts. ● Examine yourself for injuries and administer first aid as needed. ● Check on the wellbeing of your neighbours; apply first aid as needed. ● Once safe, monitor news sources (radio, TV, social media, etc.) for emergency information. ● If there are aftershocks, be prepared to Drop, Cover, and Hold On again.
● Bolt heavy furniture, water tanks, water heaters, gas cylinders and storage units to a wall or floor.	During an Earthquake: If you are in bed – Stay calm; lie face down and cover your head with pillows or blankets for protection. – Stay away from windows and unsecure objects.	DO NOT: ● Do not light a match or turn on a light switch. Use a flashlight instead.
● Place the largest and heaviest items on lower shelves.	If you are in a moving vehicle – Stop the vehicle as quickly as possible and stay in the vehicle – Avoid stopping near or under bridges, near buildings, trees, overpasses or utility wires. – Proceed cautiously once the earthquake has stopped.	● Never touch fallen power lines.
● Emergency items such as canned foods, medication, flashlights, battery-operated radios, fire extinguishers and a First Aid kit should be readily available and working properly.	If you are outside – Get away from buildings, trees, wires, or any potential falling objects. – Stay in a clear area until the shaking stops.	● Leave the streets clear for emergency and rescue vehicles.
● All family members should know how to use this emergency equipment and should know how to turn off electricity, gas and water using safety valves and main switches.	Drop Cover and Hold advice for differently abled. ● If you are unable to Drop, Cover and Hold on, get as low as possible and move away from windows or other items that can fall on you. ● Do not try to transfer from your wheelchair, recliner, or bed during the shaking. Wait for the shaking to stop before transferring.	● Do not attempt to move seriously injured persons unless they are in danger of further injury.
● Try to stay calm. Take deep breaths. It can help you relax. The calmer you are, the better decisions you would make.
● All family members should know what to do during an earthquake, and should practice these safety tips through regular drills.
● Build your home in accordance with the recommended building codes. See your local disaster management office for details.