Earth's Geology, Our Vulnerabilities

Canada, leading an initiative to be shared by the international scientific community, has undertaken the installation of three seismic stations spaced 50 kilometers apart, in the Haitian capital of Port-au-Prince. Their purpose: to detect otherwise-imperceptible tremors and quakes and, of course, larger jolts such as the one that devastated Haiti a mere month earlier.

Those jolts, of a less impressively destructive variety, are still ongoing. One was picked up a quarter-hour after the installation had been switched on.

The three stations were carefully positioned to ensure as little interference as possible with the critical seismic measurements. Each station is valued at $45,000 with the inclusion of a seismic sensor anchored within a concrete paid, along with solar panels for power-provision, and a 1.8-metre-wide satellite dish capable of relaying the data back to the receiving laboratory at Natural Resources Canada.

The team installed at the Geological Survey of Canada stationed in Ottawa, scrutinizes the recovered data, picking up dozens of tremors along the Haiti faultline to attempt to fully understand the ongoing quake threats in a country with a history of violent tremors, to gauge the impact for the country in the future, while it rebuilds itself. Seismic monitors in Puerto Rico, Jamaica and Cuba had picked up data of the cataclysmic quake that shook Haiti.

Placing the three stations at strategic places within the country itself provides a far clearer understanding of what is occurring underground. "We can see about 100 times more events", geologist David McCormack said. Explaining that quakes rupture the surface only when the geological action that leads to them are produced sufficiently close to the surface.

The devastating January 12 earthquake began with a rupture roughly 12 kilometres below surface, resulting in a rupture two kilometres below the surface. That rupture was 40 kilometres long, resulting in two plates bordering the fault sliding a few metres, releasing pressure that had been building for several centuries. Additional strain has been created on the ends of the rupture zone.

And the $64-thousand question now is the future of that added pressure placed on the eastern end of the fault, close to Port-au-Prince. Seismologists now estimate a 50% chance of another major earthquake sometime in the next half-century. The seismic-measurement installations will assist researchers in reading the potential threat and the possible intensity of anticipated quakes.

"The plates keep moving and earthquakes keep happening, that's just the way the world works."