Faults and Earthquakes in the Greater NY City Area

Reflections at the Intersection of Science, the Media, and the Public

Alan Kafka
Weston Observatory
Department of Earth and Environmental Sciences
Boston College

Like many seismologists, I spend a great deal of my time at the intersection of science, the media, and public awareness. A major challenge that seismologists (and other scientists) face is how to make our science accessible to the public without misleading them with unwarranted claims of certainty. When scientists make claims of certainty, which are then reported (or misreported) by the media, it may in the short term feed the public’s hunger for certainty in an uncertain world, but in the longer run it undermines the scientific enterprise and does a disservice to the public.

Recent news reports about a supposed discovery of geologically mapped faults that are responsible for earthquakes in the New York City area (and the alarming “news” that one of those faults runs close to the Indian Point nuclear power plant) have given me the opportunity to muse once again on how the reports of seismological studies might be heard and interpreted by the general public.

First, the bottom line: Yes, there is an earthquake hazard in the greater New York City area (albeit less than in California), a hazard that we would be foolish to ignore. But if one claims (without scientific justification) that earthquakes are concentrated on a particular fault and that therefore future large earthquakes will occur along that same fault, then one is also claiming (without scientific justification) that the earthquake hazard is less in other nearby areas. This is a technical result of the way that earthquake hazard probabilities are determined: There is a certain number of earthquakes that are likely to occur in a given region, and if many of them are forecasted to occur in one part of the region, then there will necessarily be fewer forecasted to occur in some other part. The resulting hazard assessment might then be focused on the wrong location, which would not help the public to make informed decisions about issues like what should or should not be done to insure the seismic safety of nuclear power plants.

So what is the “news”? The New York Times, the ScienceDaily website, and other news media recently reported on the results of a Columbia University study of earthquakes in the Greater New York City area. This study by Sykes et al. (2008) presents a case for hypothesized relationships between mapped faults and earthquakes in this highly populated and densely urbanized region.

The New York Times headline: Study Maps Faults for New York Quakes. The ScienceDaily headline: Earthquakes May Endanger New York More Than Thought; Nuclear Power Plant Seen As Particular Risk.

According to the New York Times article, the Columbia University group “mapped out a family of faults responsible for most of the earthquakes.” The Times article also reported that the group “found a previously unidentified boundary, likely a fault, that runs 25 miles to Peekskill, N.Y., from Stamford, Conn., passing within a mile of Indian Point.”

According to the ScienceDaily report the study “found concrete evidence for one significant previously unknown structure: an active seismic zone running at least 25 miles from Stamford, Conn., to the Hudson Valley town of Peekskill, N.Y., where it passes less than a mile north of the Indian Point nuclear power plant.” ScienceDaily also reported that the “Ramapo Seismic Zone” is a “previously known feature” that “runs from eastern Pennsylvania to the mid-Hudson Valley, passing within a mile or two northwest of Indian Point.”

Most readers of these articles would be led to believe that there has been some great new discovery regarding the activity of geologically mapped faults that threaten specific locations in the New York City area. But for me – having spent several decades immersed in the study of seismicity in the Northeast – what is most striking is how little has changed about our knowledge on this issue compared to what was known in the mid 1980s! If there is a “news” story here at all, it is the startling revelation that, after a very thorough analysis of two additional decades of earthquake monitoring, we are left with just as many questions and unresolved issues about faults and earthquakes in the New York City area as we had in the ’80s.

Back in 1978, Aggarwal and Sykes concluded that “seismic activity in the greater New York City area is concentrated along several northeast-trending faults of which the Ramapo fault appears to be the most active,” and they emphasized the importance of how that conclusion needed to be considered in discussions of the seismic safety of the Indian Point nuclear power plant. However, based on our analysis of the data available through 1983, my colleagues and I concluded (Kafka et. al, 1985) that the network seismicity “does not necessarily indicate whether [the Ramapo] fault is either the most active fault in the greater New York City area or if it is the fault along which the largest earthquakes will occur in the future,” and that “the geologic structures associated with most (if not all) earthquakes in this region are still unknown.”

As we demonstrated in 1985, the existence of a “Ramapo Seismic Zone” (RSZ) is very difficult to disentangle from the fact that many of the seismic stations are located in the vicinity of the hypothesized seismic zone, which results in a seismicity map that is biased towards highlighting that zone. If the seismic data for the New York City area is reanalyzed to minimize this bias, the existence of the proposed seismic zone is not so clear, and the distribution of epicenters lends itself to many possible conjectures of hypothetical fault zones, all of which are based on circumstantial evidence. None of these hypotheses can be considered as “concrete evidence” that the site of the Indian Point nuclear power plant is necessarily any more seismically active than many other sites in the study area. (Click here for a more detailed explanation of the complexities of demonstrating the existence of a “seismic zone” when many seismic stations are located in the vicinity of that hypothesized seismic zone.)

Conveying a scientific result as more certain than it really is feeds the appetite of a public hungry for certainty in an uncertain world. By highlighting the discussion of the RSZ (or the newly hypothesized seismic zone between Peekskill and Stamford) as if it was a “discovery” (as opposed to an interesting, but still speculative hypothesis), the impression is given once again that our understanding of the relationship between faults and earthquakes in this region is clear when in fact it isn’t.

Does any of this matter? Is this just an academic discussion? In 2000, I wrote an opinion piece in Seismological Research Letters, entitled Public Misconceptions about Faults and Earthquakes in the Eastern United States: Is it Our Own Fault?, explaining why I don’t think this is just an academic matter.

Based on the availability of new and revised earthquake data resulting from the Columbia University study, my opinion hasn’t changed from what I wrote in 2000. Yes, it does go beyond being just an academic matter when reports are made of discoveries of correlations between faults and earthquakes, when in reality what is found is at best anecdotal evidence.

In this particular case, it does not help the public to make informed decisions about the seismic safety of nuclear power plants when we are not careful to distinguish between our interesting hypotheses supported by anecdotal evidence versus scientifically-tested hypotheses that are well supported by data.

September, 2008

19 thoughts on “Faults and Earthquakes in the Greater NY City Area

  1. This has as much to do with the lack of integrity by major media news outlets as it does with the general lack of understanding about seismology, and science in general. These news providers are looking for whatever sells papers, ratings, mouse clicks, etc. They are run like a business and Sensationalism sells. It’s an unpleasant side effect of an increasingly “bottom line” driven society. Not that the other side of that coin is necessarily more desirable. But all bitter and cynical rantings aside…
    From an information dissemination side, I think this also has to do with the lack of kowledge base where seismology is concerned, and really the concept of science in general. People are fed information about faults and earthquake probabilities without any previous information about the concepts aside from the words “faults” and “earthquake” and the damage they can do. Most people have absolutely no idea what an earthquake really is, aside from terrifying ground shaking that occurs and that they supposedly come from these things called “faults”. We need to have more education in the sciences, particularly in explaining what science really is. Because it’s my experience that most people don’t know. They think that it’s definitive answers. Science is not answers, science is the process of searching for answers. And all the beauty and wonder that comes with it.

  2. I am glad I found your site on yahoo. Thanks for the sensible critique. Me and my neighbour were just preparing to do some research about this. I am very glad to see such reliable information being shared for free out there.
    Best Regards,
    Conn from Seattle city

  3. Quite absorbing. I’d absolutely like to read more about this. Does anybody have any advice where I can acquire some further resources? Appreciate it.

  4. I am curious, in light of the recent event in Japan, if anyone has mapped worldwide faults and power plants or other potentially-hazardous commercial/government enterprises which could cause collateral disasters if they were impacted by earthquakes. Do you have any information or suggestions along those lines of inquiry?

  5. In studying topographic maps of the area between Peekskill and Stamford, if a fault existed I would expect it to have left superficial traces; i.e., fault valleys, somewhere in a band between the two towns. But I haven’t found any. All the obvious fault valleys, such as the Croton River gorge’s, trend SW-NE. Numerous ridges separate Peekskill and Stamford, and nothing like a break due to faulting can I see.

  6. Is there any explanation for the Maine 2.2 quake this week? (copy from USGS recent quake:) Thank you!
    Update time = Sat Mar 26 9:05:36 EDT 2011
    Here are the earthquakes appearing on this map, most recent at top …

    y/m/d h:m:s deg deg km

    2.2 2011/03/25 06:35:47 45.259N 68.383W 9.2 62 km (38 mi) NE of Bangor,ME
    2.0 2011/01/31 03:06:14 45.052N 67.105W 7.3 108 km (67 mi) SSW of Fredericton, N.B.
    1.4 2011/01/05 01:17:46 44.571N 67.033W 6.1 107 km (66 mi) E of Bar Harbor,ME
    1.5 2010/10/16 15:11:23 45.203N 67.049W 0.5 90 km (56 mi) SSW of Fredericton, N.B

  7. The reference that Indian is the highest risk plant is not correct. The referenced study was to determine which plants need to update their analysis not their actual siesmic hazard. The study is being misapplied by politicians and the governor who don’t know better or don’t want to know better because of who supplies their campaign funding.

  8. I beleive that media awareness for these kinds of events should increase. But the sensationalism started by the media is the real problem. If the media weren’t sensational, networks like NBC, Eyewitness, FOX, ABC, CNN, and MSNBC would be out of business. My personnel opinion on the topic itself though is that we should be prepared as I beleive the next NYC quake, reguardless of any particular hypothetical or proven fault line it occurs on, could occur soon and the likelyhood of it occuring only increases as each day passes. If we are smart though, wether we are a seismologist working in the area, or just the average everyday joe, we can all take precautions to outpace another event.

  9. Not to mention that we aren’t very sure what magnitude the next event could be. I personnely beleive it will be a moderate one within the 5-5.9 range around the intensity of VII or VIII. But it could be 6-6.9, or 7-7.9, or even 8. Scientists have come up with frequencies for these events. 5-5.9 every 100 years. 6-6.9 every 1000 years. 7-7.9 every 3600 years. But whatever the magnitude is we aren’t nearly as ready as we should be.

  10. Perhaps it would be best to just keep the public informed though without a media spin. The public should also keep in mind how new seismology is. Especially intraplate seismolgy. Very little is understood about these quakes and very little can be suggested about their causes. I beleive it’s probably stress from other boundries on the plate or perhaps ancient stress accumulated overtime naturally. But i could be wrong.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s