Camilla Cattania (left) and William Frank are assistant professors in the Department of Earth, Atmospheric and Planetary Sciences focused on earthquake science. Credit: Photos thanks to the professors
Q: Why is Haiti prone to earthquakes?
Cattania: Ill start with the broad tectonics setting. The island of Hispaniola, which consists of Haiti and the Dominican Republic, is sandwiched in between the North American plate to the north and the Caribbean plate to the south. Haiti is primarily on a tiny plate thats sandwiched in between the two. At each plate border it has faults, fractures within the Earths crust, running around east to west. The earthquake happened in the southern-most fault system, called the Enriquillo-Plantain Garden fault system, where there are faults with somewhat different orientations, developing complex fault geometry. The northern plate is relocating to the west while the southern plate is transferring to the east, causing earthquakes along this fault zone.
Frank: Not only do you have the moving motion from east to west, but you likewise have compressive, or squeezing, movement at the plate limit that is accommodated by other close-by faults. One of the big questions for the 2010 earthquake is: What fault did it actually occur on? It looked like it was ideal next Enriquillo-Plantain Garden fault system, however was it was on a translational, or sliding, fault or a compressive fault? There are lots of exceptional questions about the intricacy of what, from far, looks simple.
Cattania: The region transitions between horizontal motion, in which plates slide past each other, to the compressive movement William explained, which has some vertical motion. Even in this earthquake, initial designs reveal that there was a little both.
The Enriquillo-Plantain Garden fault system has been associated with earthquakes in 1751, 1770, 1860, without much in between. The 2010 earthquake, which took place on a subsidiary fault, further increased the stress at the area of the 2021 earthquake.
The Gonâve microplate and surrounding fault zones. Credit: NASA WorldWind (retouched by mikenorton).
Q: What is the same and what is various about this earthquake versus the 2010 earthquake?
Frank: The 2010 earthquake occurred on a fault that wasnt previously determined, among the faults that accommodates the compressive motion of the plate boundary. The question we have now is whether this recent earthquake is on the primary translational fault, or whether its likewise on another fault that accommodates compressive movement. If that were the case, it would be the very same plate boundary, but a different faulting program.
Cattania: The factor there are so numerous unknowns is due to the fact that this region was very sparsely instrumented up till 2010, when Haiti had no irreversible seismic network. The quality of the data that we have from this earthquake is remarkable compared to anything we would have had in 2010 or previously.
Frank: Increased instrumentation allows us to get a much better image of whats occurring in the fault zone during the main earthquake and the aftershocks that follow. The parallel story on why thats possible is that throughout the 2010 earthquake, there was no seismology at the State University of Haiti. Now, theres a geoscience department thats recruiting and training seismologists.
Theres an informative site that is the outcome of an interesting collaboration in between geoscience scientists in Haiti and the University of Nice in France, where they release real-time areas and detections of aftershocks. It provides enormous amounts of data that is openly available. In general, theres a lot more activity within Haiti, of instrumentation, of basic interest in earthquake risk, and of people to study the information, than there was during the 2010 earthquake.
Cattania: Another distinction between these events was their magnitude. The place was likewise different– the first was closer to Port-au-Prince and usually more inhabited locations.
Q: What does your research study inform us about future earthquakes in this area? What do we understand as a scientific community?
Cattania: We can not predict with certainty the place or the magnitude of big earthquakes in this area, or anywhere else; nevertheless, we do know the normal properties of aftershocks. Essentially, you will feel numerous earthquakes in the first couple of weeks, and then this number slowly goes down unless one of these earthquakes happens to be big enough to begin a new sequence.
We had an earthquake in 2010 that happened to the east of the current earthquake, and it increased the amount of stress where the 2021 earthquake took place. If you look at a map of this location, its clear that there are other sectors of this exact same fault system on which major earthquakes havent happened for a long time.
Frank: For me, whats most associated to my research study is developing efficient ways to discover, identify, and characterize the aftershocks. Weve established signal processing methods that we can use on the seismic information to identify the earthquakes, and when were able to determine them, were able to get excellent places. Were able to study the incident rate of these aftershocks.
These aftershock catalogs are incredibly important to understanding the degree of rupture and to identifying the actual faults and aircrafts that they occur on. There are two simple ways to determine the structure. You can take a look at the primary earthquake itself, or at the rupture zone of the main earthquake, where the aftershocks frequently define where the primary earthquake happened. And as soon as you can identify, locate, and identify those aftershocks, you can much better model the earthquake.
Cattania: My work has been about consisting of geometrical intricacy in aftershock projections. When youre attempting to find out where aftershocks will happen, you require to referred to as much as possible about the orientation of existing faults, and often you need to make simplified presumptions about it. Ive developed methods that help better include everything we understand, utilizing data and the kind of details that William was describing, to attempt to infer how an aftershock will develop given what the fault geometry looks like and how variable it remains in this region. My methods permit you to take refined information about fault geometry to produce better aftershock forecasts.
Frank: Thats why Im thrilled to be here with Camilla– because we can make that direct connection.
Two assistant professors in the MIT Department of Earth, Atmospheric and Planetary Sciences go over why the area is susceptible to earthquakes and what has changed– in Haiti and in earthquake science– because the disastrous 2010 occasion, when the country had just one seismometer.
The 2010 earthquake, which took place on a subsidiary fault, even more increased the stress at the area of the 2021 earthquake.
In general, theres much more activity within Haiti, of instrumentation, of basic interest in earthquake threat, and of individuals to study the information, than there was during the 2010 earthquake.
We had an earthquake in 2010 that occurred to the east of the existing earthquake, and it increased the amount of stress where the 2021 earthquake occurred. You can look at the primary earthquake itself, or at the rupture zone of the primary earthquake, where the aftershocks typically define where the main earthquake took place.
Haiti earthquake damage.
Assistant professors Camilla Cattania and William Frank go over the science behind the 2010 and 2021 earthquakes in Haiti.
On August 14, 2021, a magnitude 7.2 earthquake struck Haiti. The biggest earthquake in the area given that 2010, the catastrophe left at least 2,000 people dead, 12,000 individuals injured, and almost 53,000 houses destroyed. Two assistant teachers in the MIT Department of Earth, Atmospheric and Planetary Sciences discuss why the area is prone to earthquakes and what has actually altered– in Haiti and in earthquake science– given that the devastating 2010 occasion, when the country had just one seismometer.
Camilla Cattania is a seismologist with experience in numerical modeling, earthquake physics, and statistical seismology; and William Frank is a geophysicist focused the physical mechanisms that manage deformation within the Earths crust.