My publications post 1987, on seismological methods of explosion monitoring, and consequences for verification of nuclear testing treaties


In the list which follows, a very short summary (indented) is given of each paper. Though I started with e-mail early -- in 1984 -- I didn't get around to HTML and distribution via the web until January 2000. So if you want copies of the earlier papers you'll have to send me an old-fashioned request for hard copy: e-mail to Paul G. Richards

Some of my papers after 1996 are accessible here online -- just keep on scrolling until you get to them.


Paul G. Richards, Stages Toward a New Test Ban, chapter 4 in the book Verification and Compliance: a Problem-Solving Approach, pp 73-91, eds M. Krepon and M. Umberger, Macmillan (U.K.) and Ballinger (U.S.A.), 1988.

Revised from an earlier paper done with A. Lindh. Gives a rationale for a Low Yield Threshold Test Ban, approached in stages.
Now outdated on policy, but relevant still on many verification issues.

Paul G. Richards, Seismic Methods for Verifying Test Ban Treaties, Chapter 4 of the book Nuclear Arms Technologies in the 1990's, edited by D. Schroeer and D. Hafemeister, AIP Conference Proceedings, 178, pp 54-108, American Institute of Physics, New York, 1988.

Summary of basic seismology, seismic data, and methods of analysis, relevant to monitoring.

Paul G. Richards, Seismic monitoring of nuclear explosions, in Encyclopedia of Geophysics, ed. D.E. James, pp 1071-1089, Van Nostrand Reinhold, 1989.

Overview, and indicates why decoupling is not feasible for clandestine testing above about 5 kt.

Paul G. Richards and John Zavales, Seismic Discrimination of Nuclear Explosions, Annual Reviews of Earth and Planetary Sciences, 18, 257-86, 1990.

Similar to the Discrimination section of the 1988 Office Technology Assessment report of the U.S. Congress (which was drafted partly by Richards).

Roger A. Hansen, Frode Ringdal, and Paul G. Richards, The Stability of RMS Lg Measurements and their Potential for Accurate Estimation of the Yields of Soviet Underground Nuclear Explosions, Bulletin of the Seismological Society of America, 8, 2106-2126, 1990.

This paper demonstrated the superb qualities of measurements made on Lg-waves, at a calibrated station, for purposes of accurate yield estimation. Single-station precision, 0.03 magnitude units.

Paul G. Richards, Nuclear Test Ban Treaties and Seismic Monitoring of Underground Nuclear Explosions: an Overview of Historical, Technical, and Recent Political Issues, unpublished ms. (for eventual book), 73 pages, 1990.

Review of much material associated with yield estimation, and how the TTBT was handled --- and mishandled.

Paul G. Richards, Progress in Seismic Verification of Test Ban Treaties, IEEE Technology and Society Magazine, 9, #4, 40-52, December 1990.

Reviews the first IRIS deployments in the USSR; RMS Lg and calibration; and the Joint Verification Experiments.

Paul G. Richards and Frederick K. Lamb, Testing Experts rebut Robinson, Arms Control Today, p22, September 1990.

An angry piece on people who say seismologists don't know what they are doing, vis-à-vis explosion monitoring. Some people in high places really are scoundrels.

Steve Taylor, Howard Patton, and Paul G. Richards, editors, Explosion Source Phenomenology, Geophysical Monograph 65, 268 pages, American Geophysical Union, Washington, DC, December 1991.

This book is a review of nuclear-explosion-generated seismic phenomena.

Paul G. Richards, How can the Operation of Thousands of Seismic Stations

Carried out by Hundreds of Institutions in Tens of Countries) Best be Focussed on Discrimination Research? text of a paper invited for the 1991 DARPA/Air Force Annual Symposium on Seismic Monitoring.

Advocates the study of "Problem Events" for purposes of developing consensus on capabilities.

Paul G. Richards, Douglas Anderson, and David Simpson, A Survey of Blasting Activity in the United States, Bulletin of the Seismological Society of America, 82, 1416-1433, June 1992.

There are about 30 explosions each day in the U.S., at 50 tons and above; and about 1 a day, at 200 tons and above: total explosive use in the U.S. is about 2 megatons each year. Concern is sometimes expressed that mine-blast signals could swamp the CTBT monitoring effort, but papers (below) show that very few of these signals will be detected by treaty-monitoring networks.

Paul G. Richards, Won-Young Kim, and Göran Ekström, The Borovoye Geophysical Observatory, Kazakhstan, feature article in EOS, Transactions of the American Geophysical Union, 73, 201 and 205-6, May 5 1992.

Describes the operation of an excellent seismic station in N. Kazakhstan, equipped with digital recording since 1966; and examples from the archive there, of Soviet nuclear explosions.

Paul G. Richards and Won-Young Kim, The Problem of Chemical Explosions and some Solutions, Proceedings of a Symposium on Technologies for Monitoring Nuclear Tests Related to Weapons Proliferation, pp 1936, Las Vegas, May 6-7, 1992.

Demonstrates practical methods for discriminating ripple-fired chemical explosions from single shot explosions such as a small UNE. Shows the need for high-frequency recording to 30 Hz.

Paul G. Richards, report to Nuclear Control Institute on signals from the seismic event of 1983 May 16, in Xinjiang Province, China, 19 pages, October 1992.

Some individuals and some newspapers have identified this event as a nuclear test conducted by China for Pakistan! My report shows why I think it was an earthquake. It had surface waves.

Frode Ringdal and Paul G. Richards, The Ukrainian event of 16 September 1979, in NORSAR Scientific Report No. 1 92/93, pp 120-124, November 1992.

Describes a subkiloton nuclear explosion not known in the West until mentioned in the Russian press. Data, of low quality, was found in the NORSAR archive. mb 3.3, about 300 tons.

Cliff H. Thurber, Howard R. Quin, and Paul G. Richards, Accurate locations of nuclear explosions in Balapan, Kazakhstan, 1987 to 1989, Geophysical Research Letters, 20, 399-402, March 5, 1993.

We used SPOT photographs, and best seismic locations, to identify surface features for specific explosions; achieved location estimates with precision about 100 meters --- a tenfold improvement.

Won-Young Kim, D.W. Simpson and Paul G. Richards, Discrimination of earthquakes and explosions in the Eastern United States using regional high-frequency data, Geophysical Review Letters, 20, 1507-1510, July 23 1993.

Demonstrates a practical method, using spectral ratios, for discriminating small earthquakes from small chemical explosions. Based upon high-frequency recording.

Paul G. Richards, Testing the test-ban treaty, "News and Views" section, Nature, 364, 188189, July 15 1993.

Overview of some key issues and capabilities, as of mid 1993.

Göran Ekström and Paul G. Richards, Empirical measurements of tectonic moment release in nuclear explosions from teleseismic surface waves and body waves Geophysical Journal International, 117, 120-140, 1994.

Shows why seismic surface waves are a very poor basis upon which to estimate yield.

Won-Young Kim, D.W. Simpson, and Paul G. Richards, High-frequency Spectra of Regional Phases from Earthquakes and Chemical Explosions, Bulletin of the Seismological Society of America, pp 1365-1386, October 1994.

Reviews the technical problems and some solutions, of identification of single-fired and ripple-fired chemical explosions under a CTBT. Has many examples of the use of spectrograms.

Vitaly I. Khalturin, Tatyana G. Rautian, and Paul G. Richards, A Study of Small Explosions and Earthquakes during 1961-1989 near the Semipalatinsk Test Site, Kazakhstan, 64 page report for DOE, 1995.

Presents regional data on about 40 small explosions, half of them chemical and half nuclear, and one small earthquake, not on usual lists of seismic events, on and near the Semipalatinsk Test Site.

Paul G. Richards, Blasting Activity of the Mining Industry in the United States, in Proceedings of a DOE/LLNL Symposium on the Non-Proliferation Experiment, April 1994, Rockville, Maryland, 1994.

There are about 10,000 explosions a year in the U.S. at 50 tons and above; but only 10 to 30 a year are detected teleseismically. So chemical explosions need not be a big problem for CTBT monitoring.

Paul G. Richards, Verification of a Comprehensive Test Ban Treaty - a Seismological Overview, pp 28-36 in Verification after the Cold War, eds J. Altmann, T. Stock, J.-P. Stroot, VU University Press, Amsterdam, 1994.

Commentary on the problems of CTBT verification, and how different organizations can contribute solutions. The seismological data gathered by the open research community will likely be needed.

Problems for CTBT Verification posed by Chemical Explosions, paper presented for the United States in Geneva, June 10, 1994, CD/NTB/WP.105, 1994.

A formal paper, developed through an interagency process in the United States, and presented in Geneva by Richards at an Experts Meeting of the Conference on Disarmament.

Paul G. Richards and John Zavales, Seismological methods for monitoring a CTBT: the technical issues arising in early negotiations, pages 53-81 in Monitoring a Comprehensive Test Ban Treaty, eds. E.S. Husebye and A.M. Dainty, Kluwer, Dordrecht, 836 pages, 1996. (text and graphics)

Reviews the technical issues that affected the history of CTBT negotiations in the period 1958-1963; and assesses whether the answers given at the time to technical questions turned out with hindsight to be correct. (Often, they were grossly wrong. The most pessimistic view of monitoring capabilities usually prevailed in the U.S. side during these negotiations.)

Paul G. Richards and Göran Ekström, Earthquake activity associated with underground nuclear explosions, in Inducing of Earthquakes by Underground Nuclear Explosions, NATO ASI Series, Partnership Sub-Series, 2. Environment Vol. 4, eds. R. Console and A. Nikolaev, pp 2134, Springer Verlag, Berlin Heidelberg, 1995.

Reviews the phenomena of tectonic release, and explosion aftershocks. Tectonic release can make an explosion have surface waves of the wrong sign. Explosion aftershocks may be important as a target for on-site inspection eforts.

Kim, W.-Y., V. Aharonian, A.L. Lerner-Lam, and P.G. Richards, Discrimination of earthquakes and explosions in Southern Russia using regional high-frequency three-component data from the IRIS/JSP Caucasus network, Bulletin of the Seismological Society of America, 87, 569-588, 1997.

Develops and evaluates a new method of discriminating between earthquakes and explosions, using three-component recordings of seismic motion and making a significant correction for the effects of recording at the Earth's free surface.
The outcome is a much better objective discriminant that works at low magnitude, for events down to a few tens of tons in yield.

Hennet, C.B., G.E. van der Vink, P.G. Richards, V.V. Adushkin, Y.F. Kopnichev, and R. Geary, Multi-use seismic stations offer strong deterrent to clandestine nuclear weapons testing, feature article in EOS, Transactions of the American Geophysical Union, 77, 289 & 300-301, July 30, 1996.

Documents the numbers of US underground nuclear explosions that were seismically detected at regional and teleseismic distances including tests that for many years were unannounced.

Richards, Paul G., Seismological Methods of Monitoring and the International Monitoring System, in The Comprehensive Test Ban Treaty: Issues and Answers, edited by Matthew McKinzie (Proceedings of a Symposium held at Cornell University, October 11 13, 1996), pp 7189, June 1997.

A review of practical problems arising in the use of seismological methods to monitor compliance with the CTBT; and of what the CTBT text has to say about seismological methods of verification.

Richards, Paul G., and Won-Young Kim, Testing the nuclear test-ban treaty, NATURE, 389, 781-782, October 23 1997.

An earthquake on 1997 August 16 near the Novaya Zemlya test site tested mechanisms for monitoring the new CTBT. Though data and open analysis gave good results, US agencies performed poorly.

Khalturin, Vitaly I., Tatyana G. Rautian, and Paul G. Richards, The seismic signal strength of chemical explosions, Bulletin of the Seismological Society of America, 88, 1511-1524, 1998.

Discusses the magnitude -yield relation for chemical explosions, and shows that such explosions are almost always more poorly coupled into seismic signal, than tamped underground nuclear explosions. This is the reason that the vast majority of mineblasts are no problem in CTBT monitoring.

Khalturin, Vitaly I., Tatyana G. Rautian, and Paul G. Richards, Magnitude distributions of mine blasting activity in different regions, technical report, 1998

Discusses the numbers of mining blasts that may be large enough to be detected by CTBT monitoring networks, showing that the largest number of such events is likely to occur in W. Siberia.

Barker, Brian, Michael Clark, Peter Davis, Mark Fisk, Michael Hedlin, Hans Israelsson, Vitaly Khalturin, Won-Young Kim, Keith McLaughlin, Charles Meade, John Murphy, Robert North, John Orcutt, Chris Powell, Paul G. Richards, Richard Stead, Jeffry Stevens, Frank Vernon, Terry Wallace, Seismology: Monitoring Nuclear Tests, Science, 281, number 5385, pages 1967-1968, issue of 25 Sept 1998.

Gives locations, magnitudes, and yield estimates, of India/Pakistan nuclear explosions on May 11, 28, and 30 of 1998; and discusses the failure to detect the announced Indian explosions of May 13.

Khalturin, Vitaly I., Tatyana G. Rautian, and Paul G. Richards, A study of small magnitude seismic events during 1961 – 1989 near and on the Semipalatinsk Test Site, Kazkhstan, accepted for publication, Pure and Applied Geophysics, 158, 143 -- 171, 2001.
[on-line version of text and graphics]
[electronic supplement covering many technical details]

There were 340 underground nuclear explosions at the Semipalatinsk Test Site. From seismic data we were able to document almost all of them, missing only two with yield announced as above 2 tons!

Paul G. Richards, Detailed description of the Semipalatinsk Test Site boundaries. (text and graphic)

This is an electronic supplement to the previous paper.

Richards, Paul G., Building the Global Seismographic Network for Test Ban Monitoring, EARTHmatters, pp 37 – 40, Fall 1999.
[on-line version of text and graphics]
[link to EARTHmatters layout].

Gives basic information on the International Monitoring System and the International Data Centre, of the Comprehensive Test Ban Treaty Organization.
I felt good about prose toward the end of this paper, which says how well seismology can support of a major arms control initiative --- until the CTBT went off-course in October 1999 in the hands of the U.S. Senate and the Clinton Administration .

Richards, Paul G., Seismological Methods of Monitoring Compliance with the Comprehensive Nuclear Test-Ban Treaty, Chapter 24 (pp. 369--382) of the International Handbook of Earthquake and Engineering Seismology, Part A, edited by W.H.K. Lee, H. Kanamori, and P. Jennings on behalf of the International Association of Seismology and Physics of the Earth's Interior, Academic Press, 2002. PDF (336K)

Reviews technical issues as of mid-2000, in the use of seismological methods for CTBT monitoring.

Richards, Paul G., Seismology and CTBT Verification, Background Paper #4, contributed for the Roundtable Discussion on the CTBT organized at Stanford University, July 19, 2000. [download pdf version]
[on-line text version]

A paper written for a forum in which most speakers were from the political arena.

V. I. Khalturin, T. G. Rautian, and P. G. Richards, Chemical Explosions during 1961--1988 on the Semipalatinsk Test Site, Kazakhstan, in Geophysics and Non-Proliferation Problems, Bulletin of the National Nuclear Center of the Republic of Kazakhstan, issue number 2, 41--44, June 2000. PDF (168K)

In addition to hundreds of underground and atmospheric nuclear explosions at the Semipalatinsk Test Site in Kazakhstan, there were a few tens of large chemical explosions.  Here, we give details on 29 of them with seismic magnitudes in the range from 3.2 to 4.4


Paul G. Richards, Won-Young Kim, and Vitaly I. Khalturin, A Plan for Location Calibration of IMS Stations in and near Kazakhstan, in Geophysics and Non-proliferation problems, issue 2, National Nuclear Centre of the Republic of Kazakhstan, June 2001.[download pdf version]

Outlines the work of a consortium, led by Lamont, that engaged in a three-year effort (which began March 2000) to improve the ability of the International Monitoring System to locate seismic events in Eastern Asia.


Granville,  John P., Won-Young Kim, and Paul G. Richards, An assessment of seismic body-wave magnitudes published by the Prototype International Data Centre, Seismological Review Letters, 73, 893--906, 2002.

This became a chapter in John Granville’s thesis, in which he showed that the teleseismic mb assigned by the pIDC (and later by the IDC) is systematically different from a classical mb, for earthquakes; but there’s not much difference between these two magnitude scales, in application to underground explosions.


Valeriu Burlacu, Mark Fisk, John Armbruster, Vitaly I. Khalturin, Won-Young Kim, Paul G. Richards, David P. Schaff, Felix Waldhauser, Michael West, Igor Morozov, Elena Morozova, Vernon Cormier, Anastasia Stroujkova, and Chandan Saikia, Development and Validation Testing of a Regionalized Travel-Time Model, and Source-Specific Station Corrections for Thirty IMS Stations and Other Stations in East Asia, Final Report on DTRA01-00-C-0031, 281 pages, August 2003. PDF (40M -- very large) is obtainable by ftp from (then cd to pub/richards and acquire the binary file VTR_2003.pdf). A short version is available as PDF (860K)

Summarizes the work over three years of a consortium, led by Lamont (which began March 2000), to improve the ability of the International Monitoring System to locate seismic events in Eastern Asia.


Felix Waldhauser, David Schaff, Paul G. Richards, and Won-Young Kim, Lop Nor Revisited: Underground Nuclear Explosion Locations, 1976-1996, from Double-difference Analysis of Regional and Teleseismic Data, Bulletin of the Seismological Society of America, 94, 1879--1889, October 2004. PDF (372K)

We give details on all the nuclear tests conducted by China, and provide accurate locations of underground tests in tunnels and vertical shafts.


Paul G. Richards, Won-Young Kim, and Vitaly I. Khalturin, A Plan for Location Calibration of IMS Stations in and near Kazakhstan, in Geophysics and Non-proliferation problems, issue 2, National Nuclear Centre of the Republic of Kazakhstan, June 2001.[download pdf version]

Outlines the work of a consortium, led by Lamont, that is engaged in a three-year effort (which began March 2000) to improve the ability of the International Monitoring System to locate seismic events in Eastern Asia.


Paul Vitaly I. Khalturin, Tatyana G. Rautian, Paul G. Richards, and William S. Leith, A review of nuclear testing by the Soviet Union at Novaya Zemlya, 1955 -- 1990, Science & Global Security, 13, 1--42, 2005. PDF (2.8M)

Apart from the technical details, this paper tells an amazing story of what it took to establish and operate the Novaya Zemlya nuclear test site in far northern latitudes (thousands of soldiers in tents through the first winter…).  Those details include basic information on tests conducted in the atmosphere, near the surface, under water, and underground.


John P. Granville, Paul G. Richards, Won-Young Kim, and Lynn R. Sykes, Understanding the difference between three teleseismic mb scales, Bulletin of the Seismological Society of America, with electronic supplement, 95, 1809--1824, October 2005. PDF (460K); also online supplement (1.7M)

Another chapter of John Granville’s thesis, showing how much the IDC mb differs from classic mb as assigned by the US Geological Survey; and what are the underlying causes of this difference.


Paul G. Richards, Forensic Seismology and CTBT verification, feature article in CTBTO Spectrum, issue no. 9, pages 1, 6, and 14, January 2007. PDF (764K)

Response to an invitation from Ola Dahman.   This journal is published by the Preparatory Commission of the CTBT Organization in Vienna, Austria.


Paul G. Richards and Won-Young Kim, Commentary: Seismic Signature, Nature Physics, 3, 4--6, January 2007. PDF (616K)

This paper, submitted a few weeks after the first nuclear test by North Korea (October 9, 2006), describes the effectiveness of the P/S spectral ratio as a seismic discriminant.  Parts of this paper appeared in the October 10, 2006, issue of the New York Times (e.g. key seismograms of the events, and of a nearby earthquake).


Won-Young Kim and Paul G. Richards, North Korean Nuclear Test: Seismic Discrimination at Low Yield, feature article in EOS, Transactions of the American Geophysical Union, 88, no. 14, pages 157 and 161, 3 April 2007. PDF (468K)

Similar to the previous paper, on the North Korean nuclear test of 2006 but with more detail, and with a comparison also to chemical explosions in Jilin province conducted in August 1998.


Paul G. Richards, CTBT Monitoring: a vital activity for our profession, Seismological Review Letters, 79, 375--378, May/June, 2008. PDF (184K)

An opinion piece, solicited by the then SRL editor (Luciana Astiz), in which I encouraged seismologists to become familiar with technical issues associated with nuclear explosion monitoring in order to promote a more informed policy debate on a major policy issue of our time (whether the CTBT should be supported, or not).


Paul G. Richards and Won-Young Kim, Monitoring for Nuclear Explosions, Scientific American, 300, 70–77, March 2009. PDF (156K) also eight-page paper (4.8M)

The editors summarize our 8-page paper very well as saying “Detecting a test of a nuclear weapon has become so effective and reliable that no nation could expect to get away with secretly exploding a device having military significance.” There are two errata (due to editors errors): the Figure showing a global map of the detection capability of the International Monitoring System did not explain that this is hypothetical---it’s what is expected if the primary network is built and operated according to specifications (but, it turns out to have been about right, now that the network is more than 80% built).  Also, there’s a mistaken sentence on the first page---about North Korea having a significant amount of weapons grade uranium---which was introduced by an editor after I’d done the page proofs! (North Korea has apparently obtained enough plutonium for several weapons.)


Lynn R. Sykes and Paul G. Richards, Seismology, in Science for Security, Verifying the Comprehensive Nuclear-Test-Ban Treaty, pages 5--10, Public Information Preparatory Commission for the CTBTO, 2009. PDF (1.2M)

Summarizes papers on seismic monitoring at the CTBTO’s ISS2009 conference in the Hofburg Palace, Vienna.


Won-Young Kim, Paul G. Richards, Diane Baker, Howard Patton, and George Randall, Improvements to a Major Digital Archive of Seismic Waveforms from Nuclear Explosions, Final Report AFRL-RV-HA-TR-2010-1024, Air Force Research Laboratory, 127 pages, 23 March 2010. PDF (8.9M)

This is the Final Report on a 20-year project to save and make openly available a major archive of digital seismic recordings of nuclear explosions from the Borovoye Observatory in Kazakhstan.  Most of the data were obtained at regional distances, and we focused on explosions in Eurasia.


Paul G. Richards and Zhongliang Wu, Seismic Monitoring of Nuclear Explosions, in Encyclopedia of Solid Earth Geophysics, ed. Harsh Gupta, Encyclopedia of Earth Sciences Series, pages 1144 to 1156, Springer: Dordrecht, The Netherlands, 2011.

Reviews technical issues as of mid-2010, in the use of seismological methods for nuclear explosion monitoring.

Zhongliang Wu and Paul G. Richards, Seismology, Monitoring of CTBT, in Encyclopedia of Solid Earth Geophysics, ed. Harsh Gupta, Encyclopedia of Earth Sciences Series, pages 1340 to 1344, Springer: Dordrecht, The Netherlands, 2011.


A companion to the previous paper, with special reference to CTBT issues.


David P. Schaff, Won-Young Kim, and Paul G. Richards,  Comments on “Radionuclide Evidence for Low-Yield Nuclear Testing in North Korea in April/May 2010”  (De Geer, S&GS issue of April 2012), submitted April 29 2012 for publication in Science & Global Security

Responds to a paper published in Volume 20 of Science & Global Security that reported evidence (from radio xenon anomalies) that North Korea might have conducted small nuclear test explosions in April and May of 2010.




go to Richards' home page at Lamont