Sports channels reported this as a (preliminary) 6.2 magnitude earthquake, said to be 97 kilometres northwest of Trinidad’s Port of Spain, with lengthy reverberations felt in St. Vincent and northeastern Guyana, and was felt just after Afghanistan beat Australia in the T20 Cricket World Cup game at Kingstown, St Vincent.
Thanks again. I contacted John Vidale at USC and he directed me to the work of Laura Wallace, which after a cursory review seems very pertinent. I’ll continue to pursue this as time allows.
Thanks so much for the response. I was watching something about the 2004 Indian Ocean EQ & tsunami and was reminded that, as massive and widespread a catastrophe that was, affecting 14 countries and causing 250,000+ deaths, it wasn’t the highest casualty disaster of this century; the 2010 Haiti Earthquake wears that dubious crown.
Sadly, it appears that whatever’s been rebuilt in Port-au-Prince has been constructed the same way that it was done before, with unreinforced concrete or unreinforced masonry. Quick, fast, cheap construction with no thought of structural integrity or saving lives.
Hopefully the poor beleaguered nation will finally get some peace instead of power playing papa docs and crumbling infrastructure.
Excellent practical advice for driving on the freeways. Good to keep in mind along with situational awareness whenever “it” finally does happen!
An excellent point. The depths for that earthquake range pretty widely - from 112 to 175 km, from the catalogs I can see - which make it difficult to tell if it occurred within the cluster, or as a separate slab-breaking event. On our cross-section above in Figure 2, the earthquake plots at ~130 km depth - a bit outside of the cluster, although for an earthquake of that magnitude the "point-source view" is incomplete. Do you know of any more detailed seismological studies of the earthquake? It would also be interesting to see if the Paria Cluster earthquakes exhibit any distinct patterns in their frequencies that would allow them to be characterized, beyond just their location and depth.
Thanks for the note, awesome! I'm a fan of your work. I was looking at the FUNVISIS Report, and the depth estimated for the Mw 7.3 was 99.6 km. Unfortunately, most researchers for years did not belong to the institution right now, and we lost this incredible opportunity associated with this event. It is not easy to access available data if it exists.
Muy interesante. I’m curious to know why a modest 6.0 with a pretty deep epicenter of 54 miles was felt over such a wide area
of 700 km (435 mi)!
The left-lateral strike-slip on the north side of the Caribbean that you referred to was also implicated in the 1692 Port Royal Jamaica earthquake, yes? Are these faults somewhat analogous to the North and East Anatolian faults? If so, could that mean that Jamaica is the next Istanbul, awaiting its next Big One?
And then, if I may, a question completely unrelated to the article, for practical purposes only…
If you were driving on a mile long freeway flyover when a big earthquake or The Big One occurred, what would you do? (Slow down, speed up, stop, ???, etc.)
It is definitely remarkable how far away earthquakes can be felt - evidence, I suppose, of just how powerful they are! That being said, "felt" can mean a lot of different things - from building collapse to a slight jolt.
Yes, the 1692 earthquake in Jamaica is thought to have occurred on one of the strike-slip faults on the north side of the Caribbean. There is a step-over in the faults in eastern Jamaica, so the situation is a bit more complicated. In terms of the analogy, there are definitely similarities to other large strike-slip systems like the North Anatolian Fault. For instance, along the North Anatolian Fault, there have been a series of large strike-slip earthquakes over the last century from east to west, where each earthquake laid the groundwork for the next by adding stress to the neighboring fault segments. As you say, this has put a lot of attention on Istanbul, as it is near the "next" earthquake segment to the west of the last large earthquake.
In Haiti, the same seems to have occurred (on a smaller scale): the 2010 M7.0 earthquake was followed by a M7.2 earthquake in 2021 to the west, and it appears that the second earthquake was made more likely by the first. (https://temblor.net/earthquake-insights/are-the-2021-and-2010-haiti-earthquakes-part-of-a-progressive-sequence-13132/) The 2021 earthquake added its own share of stress. However, Jamaica is quite far away; the fault there has not been additionally stressed by the earthquake sequence. Earthquakes there are possible, but the fault there is not (yet) significantly influenced by the Haiti sequence.
The general rule of thumb for driving in an earthquake is to stop. As you point out, in some cases that can be dangerous - there is some remarkable footage from Taiwan of people on mountain roads driving to the nearest earthquake shelter, where there is protection from rock falls. However, my guess is that on a flyover, it is more likely that there would be damage to part of the flyover rather than collapse of the entire thing. If you stopped, you would only be exposed to whatever damage occurred at your location; if you kept driving, you would be exposed to damage across the whole thing - plus the shaking could cause you to lose control.
That being said, if you received an early warning of upcoming shaking on your phone and you were close enough to the end to drive off of the flyover in the seconds available, that might be your best option.
I’m curious to learn if this subduction zone also exhibits tremor, and if, as a subduction trench, the plate is always actively subducting, or is locked in part and infrequently capable of generating even larger events? If there is tremor is it tracked and recorded? Are these events occurring inside the descending slab as Benioff events? Has it ever been noted that there was tremor subsequent to an event?
After a pretty superficial literature search, it looks like there is not much in the way of non-volcanic tremor - one group used ocean-bottom seismometers to look, but the signals they found could mostly be attributed to noise. (https://doi.org/10.1016/j.tecto.2012.10.031) In contrast, there *is* evidence of large megathrust earthquakes - like a M8.5 in 1843. (https://en.wikipedia.org/wiki/1843_Guadeloupe_earthquake)
It would certainly be interesting to see whether tremor activates after large megathrust earthquakes. The authors of the study above note that there could well be transient signals that they missed because their deployment was short.
Thanks very much. I apologize that his response is overly long, but it’s hopefully thus self explanatory.
I’ve been pursuing an amateur interest in tectonic activity since I started reading papers on the subject in the 1970s. Since my career was in banking, and lacking formal training and accreditation in your field of expertise, I necessarily rely on you professionals as i seek answers to questions I formulate.
Among those is whether seismology can determine if there may be a relationship between tremor and several of the tectonic phenomenon, most importantly mega events, but also damaging Benioff quakes.
The year I was born, 1949, there was a large, destructive Benioff event under south Puget Sound, WA State. There had been another in 1939, and likely others since European and American settlers arrived, and they’d undoubtedly been experienced by Native Americans. Since 1949 there was one in my sophomore year in high school, 1965, and again in 2001. There are relatively frequent small Benioff events in Cascadia, but the big ones are confined to S Puget Sound and spaced randomly, usually by decades.
The Mega event that science is anticipating is surely to be feared and planned for, but the events in 1939, 1949, ‘65, and ‘01 killed and injured dozens and did billions in public and private property damage. Their consequences will only get worse as growth continues.
Since PNSN began posting ETS and tremor activity in 2008 I’ve been watching it, as well as reading about similar tremor activity in similar subduction zones, primarily Japan. I began to notice a year or so again that the small Benioff events under the NW, from Canada to Mendocino, seem at times to occur subsequent to local tremor activity, and while correlation isn’t causation it piqued my curiosity regarding a possible relationship.
So, I’ve begun, piecemeal, and in an untrained fashion, like an amateur looking for comets, to see what data I can collect to construct an argument that fleshes out my hypothesis.
I’m not anticipating predictions but I do suspect that a variable probability forecast might be possible based on tremor activity specific to the S Puget Sound “Pinch,” that zone under S Puget Sound in which the subducting plate twists somewhat In its descent.
Unfortunately, where S Puget Sound, the location of our largest damaging Benioffs, is concerned, the collection of tremor data didn’t begin until after the last big event in 2001. There’s no way for me, at age 75, relying on internet investigation, without resources, time, training and data, to establish a conclusion that verifies or disproves my hypothesis.
But I keep slogging along and the Caribbean/South America trench is one more possible source of input as to a possible relationship.
Very interesting! A link is definitely plausible. I found a handful of papers tying tremor to intraslab (Benioff) events - you might have run into some of these already. The direction of causality is a bit mixed: some of the studies suggest intraslab earthquakes triggered by slow slip/tremor; others propose that the triggering goes the other way. In general, these studies look at small, rather than large, events; it's always tricky when looking at rare large earthquakes to know what behavior is causally linked and tells us about universal behavior, and what behavior is because of some unique characteristic of the earthquake, or just random variation.
I appreciate your thoughts about the impact of smaller, more frequent damaging events compared to rare devastating ones. I remember that this topic popped up in my thesis defense - I was asked whether it would be better for LA to suffer one M8 earthquake every century, or 30 M7's - scenarios with equal earthquake moment release. Of course, with intraslab vs. megathrust earthquakes it's not an either-or situation. And intraslab earthquakes can get quite large - I believe the largest recorded was a M8.3 offshore Hokkaido.
Here are the papers I found:
Vidale et al. (2011): Five very small intraslab earthquakes were observed, triggered by nearby tremor and slow slip, in Cascadia. - https://doi.org/10.1029/2011GC003559
Seno and Yamasaki (2003): In Southwest Japan, areas without tremor also don't exhibit intraslab seismicity. They interpret that both processes are related to fluids being expelled from the slab, which both makes the slab more brittle, and increases pore fluid pressure on the plate boundary. https://doi.org/10.1029/2003GL018349
Kita et al. (2021): Again Southwest Japan; they observe high seismicity rates in the slab before slow slip with tremor, again linking it to fluids. https://doi.org/10.1038/s41467-021-27453-8
Wickham-Piotrowski et al. (2024): In Ecuador, they observed a sequence that included both intraslab seismicity and slow slip, and suggest that the slow slip on the megathrust triggered slow slip on a fault within the slab, which in turn drove seismicity in the slab. https://doi.org/10.1016/j.tecto.2024.230365
Thanks very much! I’ve read some papers investigating a possible relationship, but not all, so, these are of interest. Regardless of what I learn about known events it remains to be seen if when the next large Benioff occurs under S Puget Sound there’s a tremor episode prior to the EQ. If they happen after these large quakes then they’re more like the rocket in a Road Runner Cartoon that goes off after the Coyote is crushed and the Road Runner is down the highway.
As for defending your thesis, at least in Japan I suspect it’s a mixed bag. The mega quakes are horrible and as was recently demonstrated in Western Japan the not Mega, but shallow large quakes are very bad. Under Puget Sound they are at least usually 40-55 kilometers deep, so ground motion and acceleration are dampened, although that’s scant relief if it’s your loved one killed or property destroyed.
ps: Examining tremor specific to the Pinch and collecting data until the next large Benioff event could provide evidence to help science establish or reject a link, and if established might help construct a method of forecasting a window during which probability is heightened, somewhat in the way we understand foreshock and aftershock occurrence and magnitude relationships.
Sports channels reported this as a (preliminary) 6.2 magnitude earthquake, said to be 97 kilometres northwest of Trinidad’s Port of Spain, with lengthy reverberations felt in St. Vincent and northeastern Guyana, and was felt just after Afghanistan beat Australia in the T20 Cricket World Cup game at Kingstown, St Vincent.
Thanks again. I contacted John Vidale at USC and he directed me to the work of Laura Wallace, which after a cursory review seems very pertinent. I’ll continue to pursue this as time allows.
https://phys.org/news/2024-05-earthquakes-permeability.html
As does this:
https://phys.org/news/2023-10-slow-slip-events-southern-costa-rica.html
Thanks so much for the response. I was watching something about the 2004 Indian Ocean EQ & tsunami and was reminded that, as massive and widespread a catastrophe that was, affecting 14 countries and causing 250,000+ deaths, it wasn’t the highest casualty disaster of this century; the 2010 Haiti Earthquake wears that dubious crown.
Sadly, it appears that whatever’s been rebuilt in Port-au-Prince has been constructed the same way that it was done before, with unreinforced concrete or unreinforced masonry. Quick, fast, cheap construction with no thought of structural integrity or saving lives.
Hopefully the poor beleaguered nation will finally get some peace instead of power playing papa docs and crumbling infrastructure.
Excellent practical advice for driving on the freeways. Good to keep in mind along with situational awareness whenever “it” finally does happen!
In the list of largest events associated to the "Paria Cluster": Mw7.3 w
21, August, 2018. https://earthquake.usgs.gov/earthquakes/eventpage/us1000gez7/executive
An excellent point. The depths for that earthquake range pretty widely - from 112 to 175 km, from the catalogs I can see - which make it difficult to tell if it occurred within the cluster, or as a separate slab-breaking event. On our cross-section above in Figure 2, the earthquake plots at ~130 km depth - a bit outside of the cluster, although for an earthquake of that magnitude the "point-source view" is incomplete. Do you know of any more detailed seismological studies of the earthquake? It would also be interesting to see if the Paria Cluster earthquakes exhibit any distinct patterns in their frequencies that would allow them to be characterized, beyond just their location and depth.
https://www.emsc-csem.org/Earthquake_information/earthquake_map.php?id=708406
I have added a note in the text above (crediting you) to highlight this earthquake. Thanks very much for your contribution!
Thanks for the note, awesome! I'm a fan of your work. I was looking at the FUNVISIS Report, and the depth estimated for the Mw 7.3 was 99.6 km. Unfortunately, most researchers for years did not belong to the institution right now, and we lost this incredible opportunity associated with this event. It is not easy to access available data if it exists.
What a shame! At 99.6 km, it does sound like this event would fall into the cluster.
Muy interesante. I’m curious to know why a modest 6.0 with a pretty deep epicenter of 54 miles was felt over such a wide area
of 700 km (435 mi)!
The left-lateral strike-slip on the north side of the Caribbean that you referred to was also implicated in the 1692 Port Royal Jamaica earthquake, yes? Are these faults somewhat analogous to the North and East Anatolian faults? If so, could that mean that Jamaica is the next Istanbul, awaiting its next Big One?
And then, if I may, a question completely unrelated to the article, for practical purposes only…
If you were driving on a mile long freeway flyover when a big earthquake or The Big One occurred, what would you do? (Slow down, speed up, stop, ???, etc.)
Thank you!!
Lots of good questions!
It is definitely remarkable how far away earthquakes can be felt - evidence, I suppose, of just how powerful they are! That being said, "felt" can mean a lot of different things - from building collapse to a slight jolt.
Yes, the 1692 earthquake in Jamaica is thought to have occurred on one of the strike-slip faults on the north side of the Caribbean. There is a step-over in the faults in eastern Jamaica, so the situation is a bit more complicated. In terms of the analogy, there are definitely similarities to other large strike-slip systems like the North Anatolian Fault. For instance, along the North Anatolian Fault, there have been a series of large strike-slip earthquakes over the last century from east to west, where each earthquake laid the groundwork for the next by adding stress to the neighboring fault segments. As you say, this has put a lot of attention on Istanbul, as it is near the "next" earthquake segment to the west of the last large earthquake.
In Haiti, the same seems to have occurred (on a smaller scale): the 2010 M7.0 earthquake was followed by a M7.2 earthquake in 2021 to the west, and it appears that the second earthquake was made more likely by the first. (https://temblor.net/earthquake-insights/are-the-2021-and-2010-haiti-earthquakes-part-of-a-progressive-sequence-13132/) The 2021 earthquake added its own share of stress. However, Jamaica is quite far away; the fault there has not been additionally stressed by the earthquake sequence. Earthquakes there are possible, but the fault there is not (yet) significantly influenced by the Haiti sequence.
The general rule of thumb for driving in an earthquake is to stop. As you point out, in some cases that can be dangerous - there is some remarkable footage from Taiwan of people on mountain roads driving to the nearest earthquake shelter, where there is protection from rock falls. However, my guess is that on a flyover, it is more likely that there would be damage to part of the flyover rather than collapse of the entire thing. If you stopped, you would only be exposed to whatever damage occurred at your location; if you kept driving, you would be exposed to damage across the whole thing - plus the shaking could cause you to lose control.
That being said, if you received an early warning of upcoming shaking on your phone and you were close enough to the end to drive off of the flyover in the seconds available, that might be your best option.
I’m curious to learn if this subduction zone also exhibits tremor, and if, as a subduction trench, the plate is always actively subducting, or is locked in part and infrequently capable of generating even larger events? If there is tremor is it tracked and recorded? Are these events occurring inside the descending slab as Benioff events? Has it ever been noted that there was tremor subsequent to an event?
Thanks very much.
John F McBride
seanmacgpo@hotmail.com
After a pretty superficial literature search, it looks like there is not much in the way of non-volcanic tremor - one group used ocean-bottom seismometers to look, but the signals they found could mostly be attributed to noise. (https://doi.org/10.1016/j.tecto.2012.10.031) In contrast, there *is* evidence of large megathrust earthquakes - like a M8.5 in 1843. (https://en.wikipedia.org/wiki/1843_Guadeloupe_earthquake)
It would certainly be interesting to see whether tremor activates after large megathrust earthquakes. The authors of the study above note that there could well be transient signals that they missed because their deployment was short.
Thanks very much. I apologize that his response is overly long, but it’s hopefully thus self explanatory.
I’ve been pursuing an amateur interest in tectonic activity since I started reading papers on the subject in the 1970s. Since my career was in banking, and lacking formal training and accreditation in your field of expertise, I necessarily rely on you professionals as i seek answers to questions I formulate.
Among those is whether seismology can determine if there may be a relationship between tremor and several of the tectonic phenomenon, most importantly mega events, but also damaging Benioff quakes.
The year I was born, 1949, there was a large, destructive Benioff event under south Puget Sound, WA State. There had been another in 1939, and likely others since European and American settlers arrived, and they’d undoubtedly been experienced by Native Americans. Since 1949 there was one in my sophomore year in high school, 1965, and again in 2001. There are relatively frequent small Benioff events in Cascadia, but the big ones are confined to S Puget Sound and spaced randomly, usually by decades.
The Mega event that science is anticipating is surely to be feared and planned for, but the events in 1939, 1949, ‘65, and ‘01 killed and injured dozens and did billions in public and private property damage. Their consequences will only get worse as growth continues.
Since PNSN began posting ETS and tremor activity in 2008 I’ve been watching it, as well as reading about similar tremor activity in similar subduction zones, primarily Japan. I began to notice a year or so again that the small Benioff events under the NW, from Canada to Mendocino, seem at times to occur subsequent to local tremor activity, and while correlation isn’t causation it piqued my curiosity regarding a possible relationship.
So, I’ve begun, piecemeal, and in an untrained fashion, like an amateur looking for comets, to see what data I can collect to construct an argument that fleshes out my hypothesis.
I’m not anticipating predictions but I do suspect that a variable probability forecast might be possible based on tremor activity specific to the S Puget Sound “Pinch,” that zone under S Puget Sound in which the subducting plate twists somewhat In its descent.
Unfortunately, where S Puget Sound, the location of our largest damaging Benioffs, is concerned, the collection of tremor data didn’t begin until after the last big event in 2001. There’s no way for me, at age 75, relying on internet investigation, without resources, time, training and data, to establish a conclusion that verifies or disproves my hypothesis.
But I keep slogging along and the Caribbean/South America trench is one more possible source of input as to a possible relationship.
Thanks.
Yours sincerely.
John F McBride
seanmacgpo@hotmail.com
Seattle WA 98115
Very interesting! A link is definitely plausible. I found a handful of papers tying tremor to intraslab (Benioff) events - you might have run into some of these already. The direction of causality is a bit mixed: some of the studies suggest intraslab earthquakes triggered by slow slip/tremor; others propose that the triggering goes the other way. In general, these studies look at small, rather than large, events; it's always tricky when looking at rare large earthquakes to know what behavior is causally linked and tells us about universal behavior, and what behavior is because of some unique characteristic of the earthquake, or just random variation.
I appreciate your thoughts about the impact of smaller, more frequent damaging events compared to rare devastating ones. I remember that this topic popped up in my thesis defense - I was asked whether it would be better for LA to suffer one M8 earthquake every century, or 30 M7's - scenarios with equal earthquake moment release. Of course, with intraslab vs. megathrust earthquakes it's not an either-or situation. And intraslab earthquakes can get quite large - I believe the largest recorded was a M8.3 offshore Hokkaido.
Here are the papers I found:
Vidale et al. (2011): Five very small intraslab earthquakes were observed, triggered by nearby tremor and slow slip, in Cascadia. - https://doi.org/10.1029/2011GC003559
Seno and Yamasaki (2003): In Southwest Japan, areas without tremor also don't exhibit intraslab seismicity. They interpret that both processes are related to fluids being expelled from the slab, which both makes the slab more brittle, and increases pore fluid pressure on the plate boundary. https://doi.org/10.1029/2003GL018349
Kita et al. (2021): Again Southwest Japan; they observe high seismicity rates in the slab before slow slip with tremor, again linking it to fluids. https://doi.org/10.1038/s41467-021-27453-8
Wickham-Piotrowski et al. (2024): In Ecuador, they observed a sequence that included both intraslab seismicity and slow slip, and suggest that the slow slip on the megathrust triggered slow slip on a fault within the slab, which in turn drove seismicity in the slab. https://doi.org/10.1016/j.tecto.2024.230365
Thanks very much! I’ve read some papers investigating a possible relationship, but not all, so, these are of interest. Regardless of what I learn about known events it remains to be seen if when the next large Benioff occurs under S Puget Sound there’s a tremor episode prior to the EQ. If they happen after these large quakes then they’re more like the rocket in a Road Runner Cartoon that goes off after the Coyote is crushed and the Road Runner is down the highway.
As for defending your thesis, at least in Japan I suspect it’s a mixed bag. The mega quakes are horrible and as was recently demonstrated in Western Japan the not Mega, but shallow large quakes are very bad. Under Puget Sound they are at least usually 40-55 kilometers deep, so ground motion and acceleration are dampened, although that’s scant relief if it’s your loved one killed or property destroyed.
John McBride
ps: Examining tremor specific to the Pinch and collecting data until the next large Benioff event could provide evidence to help science establish or reject a link, and if established might help construct a method of forecasting a window during which probability is heightened, somewhat in the way we understand foreshock and aftershock occurrence and magnitude relationships.
JFM