Tuesday, January 21, 2014

Puerto Rico Earthquake Swarm

On January 13th news outlets reported a 6.4 quake along the northern coast of Puerto Rico, and just as the world recently became acquainted with the 'polar vortex' (previously known as a cold front), armchair seismologists were introduced to the Puerto Rico Trench. Lying just north of Puerto Rico, stretching roughly 800 miles, this topographical ditch in the Atlantic has been around for a long time, but a local awareness of plate tectonics and the forces at work that can produce earthquakes and subsequent tsunami's have not. Just as the unfamiliar term "storm surge" confused many in the Philippines and resulted in many staying in harms way as Super Typhoon Yolanda made landfall, a lack of familiarity with Earthquakes and Tsunami's in Puerto Rico mean that there is a lower level of awareness around quake preparedness. Then factor in that the last major earthquake to hit the island was in 1918 and you've got a recipe for an unmotivated public with no frame of reference when it comes to earthquakes.

And if you think that a one-off 6.5 quake isn't going to change attitudes, you're probably right, but what about the other 400+ quakes the region has experienced in the last week? While seismologists are quick to tell you that hundreds of earthquakes happen around the world everyday, the clustering and frequency of the earthquake activity around Puerto Rico has to make you wonder if something else is going on.

Compare the above to the earthquake activity in the last week in southern CA:

Does all of this seismic activity in Puerto Rico point to a larger earthquake event on the horizon? In most circumstances one would look to history for some context, but earthquake swarms, like the ones near Puerto Rico are not that well understood and answers to what is currently happening are not readily available by looking to the past. When a swarm generates a lot of small tremors, they usually fizzle out, but scientists don't understand why, so the answer to whether or not the Puerto Rico Trench is just getting warmed up remains to be seen.

While the causes and ultimate outcomes of the increased seismic activity remain a mystery, these quakes offer an opportunity to talk about the natural hazards Puerto Rico faces...especially earthquakes and tsunami's. One of the challenges in preparedness is to make people believe that the event in question can and will happen to them. For those in Puerto Rico, I hope that the attention the quakes are receiving will push these uncomfortable "what if" conversations that are generally avoided to the forefront of daily conversations. It's only when disasters are talked about that questions are asked and answers are sought. And while the constant rumblings of the earth make for sleepless nights, it's a reminder that we need to stay vigilant and continually press for greater engagement of our community partners so that when something does happen, people are prepared and communities are ready to recover.

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