T&T scientists seek $$ for earthquake study

(Trinidad Express) The Seismic Research Centre (SRC) is working with foreign scientists to raise funds to conduct further investigations of the Central Range Fault line.

The results of previous studies have raised concerns that an earthquake with devastating consequences can be triggered along this fault line.

The entire Central Range-Warm Springs Fault Zone runs roughly from Manzanilla to Claxton Bay…it also extends offshore on both sides of the island.

Studies on the fault which began in earnest in the early 1990s determined that it is active and has triggered large earthquakes in the past.

Research fellow (Instrumentation) at the SRC, Lloyd Lynch told the Express that scientists at the SRC believe the fault is accumulating strain and could generate a large earthquake.

Lloyd Lynch
Lloyd Lynch

If there is a rupture of the whole length of the fault line, which is not impossible, this will amount to a magnitude 7.5 earthquake said Lynch who added that the public must be made aware of this “huge threat”.

“It’s certainly a very important enough problem. The consequences of having a large earthquake in the middle of the country is worth spending a few hundreds of thousands of dollars to determine for sure what is happening,” said Lynch.

Faults are elastic systems, they acquire strain and when the strain exceeds the crustal friction (friction in the crustal rocks), the elastic strain rebounds, there is a slip…that sudden slip is what manifests itself as an earthquake, explained Lynch.
The SRC has designed an experiment to instrument the fault, which will provide clues as to what is really going on at the depth. Lynch said scientist Dr John Webber who has been investigating the fault line since the 90s has taken a keen interest and is trying to raise more funds to do more thorough research. Webber and the SRC are also trying to get more researchers involved to look into other aspects. Lynch added that the SRC is looking to install more seismic instruments close to the fault line, this includes strong motion instruments, GPS units and four high geared seismometers (instruments that sense vibrations in the earth).

If we should have a magnitude 7.0 along the Central Range —which is a fault line that is exposed so it means that the depth is going to be shallow—we will experience lateral shaking that is greater than or equal to half the weight of any structure, said Lynch.

“Currently building codes used in Trinidad cater for lateral loads to the tune of .3 or a third of the weight of the structure. Most of the residential structures which are not conformed to building codes will not withstand shaking greater than .2 or one fifth of the weight of the structure,” said Lynch, who is also a member of the building codes committee which was set up in the wake of the devastating 2010 earthquake in Haiti.

“So magnitude 7.0 or greater in Trinidad within 30 kms north of the Cental Range and 30 kms south of the Central Range, you are likely to get extremely high ground motion and because of the magnitude you will experience this for 40 or 50 seconds which is long enough to destroy most structures that we have currently on the island. So the prospects are not very bright, they’re dull.”

In the event of an earthquake of such magnitude, ground rupture, fires, landslides and inundation of coastlines are also likely to occur. Lynch said this country has not developed any sort of resilience adding that buildings are poorly constructed.
“If this big event that we’re expecting does not happen in 40 – 50 years, the fund would have accumulated a significant amount that would go a long way in terms of rehabilitation and so on,”said Lynch.

“I pray that it does not happen in my lifetime…certainly I hate to think about what would happen, how an event like that would make one’s life miserable, not to mention the whole country,” he said.

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