Scientists from Columbia University’s Earth Institute and Lamont-Doherty Earth Observatory have provided some photographs and commented analysis of the earthquake in Haiti.
–Photo from the scene. Preparing to move the injured from the UN Development Program compound. Uploaded from cell phone. Marc Levy, The Earth Institute, Columbia University.
MINUSTAH HQ building, Haiti. Photo by Marc Levy.
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From Arthur Lerner-Lam Lamont, Doherty Senior Research Scientist, Seismology Geology and Tectonophysics:
There are several global plate tectonic models in common use for global earthquake hazard. Recent earthquakes are used to delineate the boundary between the Caribbean Plate and North American plate, which runs through Hispaniola. The boundary is characterized in these models as a simple strike-slip (lateral) fault system, extending west from the Puerto Rican trench and running to the north of Hispaniola. It’s not that simple.
In a Nature paper published in 1985, three Lamonters (students of Lynn Sykes) postulated that the boundary was twinned, with a second, active segment running parallel along the southern margin of Hispaniola, along the Cayman Trough. This segment does not have a lot of earthquakes relative to the northern branch, but their analysis suggested that this is because it may be “locked” between the occurrence of larger events. The global plate models took the lack of earthquakes as an indication that most of the relative plate motion is occurring along the northern segment. However, using this as the basis for the calculation of hazard potential is incomplete; a locked fault is very dangerous. Sykes et al. have been proven right (unfortunately).
The implications for future hazard are these: The fault that ruptured yesterday is a major component of a complex fault system – comprised of intertwined branches, not unlike the San Andreas in California or the Northern Anatolian Fault in northern Turkey. The release of stress yesterday has most likely loaded segments of this fault east and west of the segment that ruptured, and advanced the time to the next rupture. The segment that ruptured is probably only a 100 km long (or less), but the southern part of the system is probably 1000 km long or more. The western segments run through Jamaica, the eastern through the DR and Puerto Rico. In the next several days, I expect that calculations will give us a better idea of the excess loading on these segments.
From Dr. Geoffrey Abers, Doherty Senior Research Scientist:
I quickly made these 2 maps as an alternative to the USGS maps, to show a somewhat larger regional context around Haiti. These are generated with (LDEO-supported) GeoMapApp software.
Hispanola1.jpg shows M>5.5 earthquakes since 1970 through some time in 2009
haiti1day.jpg shows the last 24h of earthquakes/aftershocks.
Observations:
– -this fault system (Enriquillo or Enriquillo-Plantain Garden FZ?) has been dead quiet for the instrumental record, despite large earthquakes in 1700’s
– -this aftershock zone is much smaller than the several hundred km length of the fault zone; loading of adjacent segments seems worth considering/evaluating. There’s a paper by Ali et al. (2008 GJI 174, 904-918) evaluating Coulomb stress buildup & interactions between this and the parallel fault system to the north, that I’m sure will be discussed in this context.
From Steve Cohen, executive director of The Earth Institute, writing in the Huffington Post that the crisis is “a critical test” for the Obama administration:
“Haiti is connected to our country by geography, family and history. We need to demonstrate American capacity and compassion in equal measure in the following weeks and months, and especially in the next 24 hours. … [But] there is a broader lesson to be taken from this disaster for both the United States and what we sometimes optimistically call the “community of nations.” As the world becomes more crowded and urbanized, the impact of natural disasters will only grow. It is not that we are seeing more hurricanes, earthquakes and floods than we used to, but rather that more people are in harm’s way than ever before. The lesson here is that we must build a global network of emergency response capacity that is far greater than the one we have now.
To whom it may concern, I would like to know about two friends living in P-au-P
Here are their names and phone number
Nidsher Lete Ph # 3842-6220 nidhou25@hotmail.com
Monise Lete Ph # 3485=6599 minou-73@hotmail.com
I would very much like to be updated on your findings regarding expectations for movement of the fault in the Cayman Trough, especially near Grand Cayman, where I live. I have long suspected that this island of 60,000 residents has grossly ignored our obvious risk for a major quake, since we have not had a big one in occupied history (250 years). My interest in the geology of the Cayman Islands has led me to believe that this stored tension is a time bomb with a burning fuse. I further suspect that Haiti’s release will have now added massive tension to this part of the fault, speeding that fuse into our bomb. Your comments seem to corroborate my suspicion. There is a perpendicular jog in the fault near us, which looks to me like an opportunity for a shearing movement, which could generate a tsunami should it take a dive. Has anybody assessed it? Thank you for your attention to this.
In 2004 we had a 5.1 quake centered 30 miles off the SW corner of Grand Cayman, which was the first time anyone here had ever even felt a relatively minor tremor and they thought it was a big, scary event. Most people here don’t even know the basic steps to take in case of a quake. They are equally clueless about what to do when a tsunami watch is announced (like we had from the Haiti quake and which few ever heard about until too late). We have no Tsunami warning sirens or public announcement plan in place either.
P.S. I used to pilot deep dive subs to 1,000′ here, which is where my awareness of our geology began.
God bless, Courtney Platt
It looks as if a ring of fire could be in the works for this region. Perhaps, both sides (i.e. the mountainous region delineating Haiti and the Dom. Rep approx.) will experience moderate to sizable earthquakes for an unforeseeable time. But I suspect more tremors to come. Look out Puerto Rico. Look out western Cuba. Look out Caribbean as a whole.
Sincerely,
Ken