JUST before 11 pm on Thursday, shaken residents in the northern part of the island took to social media to alert friends and family with a ubiquitous, “Earthquake” update.
The tremor lasted, according to some, about a minute. The UWI Seismic Research Centre quickly responded with its own Facebook update that an earthquake measuring 5.0 pm the Richter scale, did indeed occur at 10:49 pm, 75 kilometres west-north-west of Port of Spain, in the Caribbean Sea, just off the coast of Venezuela.
Earlier that day, Seismologist Dr Ilias Papadopoulos, a Research Fellow in Engineering Seismology at the Centre, had given a presentation to members of the Port of Spain Central Rotary Club about the risk of earthquakes to TT.
The country, he noted, is located at the convergence of three tectonic plates— the Caribbean, North American and South American— part of the earth’s rocky crust that glide over the mantle, the second layer of molten rock.
Trinidad, in particular, is split in two, with half the country part of the North American plate, and the next part of the South American— demarcated by the Central Range.
The country gets 2,200 earthquakes a year— ten to 15 a day—but most are so small that only the most sensitive scientific instruments pick them up. The recent activity caused by Grenada’s underwater volcano, Kick ‘Em Jenny, has brought that up to about 50 to 70 per day.
While most destruction caused by earthquakes is caused because of poor construction, Papadopolous said the biggest risk to Trinidad—or rather, Port of Spain—is liquefaction.
Liquefaction, as the name suggests, is when a solid behaves like a liquid when under stress—for example, land that is waterlogged is shaken during an earthquake. This can cause buildings or other material to sink into the ground, and when the stress is removed, that is, the shaking stops, stay there, stuck because the earth has returned to its solid state.
“Port of Spain is in grave danger because the water in the subsurface is shallow— you only have to dig a metre down to find water,” Papadopolous said.
Luckily, despite another aftershock yesterday afternoon at about 2pm, the city still stands.