Color Illustrations

The Mike thermonuclear (hydrogen bomb) explosion. Photo by U.S. Atomic Energy Commission.

Depths (vertical axis) for conducting decoupled nuclear explosions in an air-filled cavity in salt. Yield of the explosion is on the horizontal axis at top; the cavity radius is at bottom. Modified from Davis and Sykes, 1999.

Seismic events and stations in the vicinity of the main Russian arctic test site at Novaya Zemlya. Red stars show the locations of nuclear tests since 1977. Small blue circles indicate seismic events from 1999 to 2009 of magnitude greater than 2.0. The primary stations of the International Monitoring Service (triangles), the auxiliary station in Sweden (square), and three other publicly available stations (pentagons) are shown in white. The orange diamond locates the Kursk submarine disaster of 2000. Many of the events in Scandinavia, Finland, and mainland Russia were small mine blasts. Source: National Academies Report, 2012.

Locations of four seismic arrays that continuously monitor the Russian test site on Novaya Zemlya (NZ). Source: Kværna, unpublished figure 2016.

Ratios of high-frequency P to S waves discriminate (identify) Novaya Zemlya nuclear tests from earthquakes. Left-hand side compares 6–8 Hz (cycles per second) seismic waves at Kevo, Finland, for the 1997 Kara Sea earthquake (in blue) with a nuclear test in 1990 (in red). Right-hand side shows P/S values for five nuclear tests, nonnuclear explosions related to the sinking of the Kursk submarine, and earthquakes on and near Novaya Zemlya. The 1997 and more recent earthquakes in 2007 and 2009 are labeled. Source: National Academies Report, 2012.

Detection capability in late 2007 of thirty-eight operating primary seismic stations of the International Monitoring System. Contours indicate the magnitude of the smallest event that would be detected with high likelihood (90 percent probability). Prepared by Kværna and Ringdal of NORSAR with yields added for National Academies Report of 2012.

Measurements of high-frequency seismic waves for earthquakes and explosions near the Chinese test site at Lop Nor from 2000 to 2008. The log of the amplitude ratio of P to Lg seismic waves is shown on the vertical axis. Triangles denote earlier nuclear explosions at regional stations in blue. Yellow circles indicate earthquakes. Explosions have higher values on the vertical axis than earthquakes for frequencies of 4 and 8 Hz (cycles per second). Source: Kim, Richards, and Sykes, 2009.

Seismic and infrasound stations of the International Monitoring System that detected the North Korean nuclear explosion of 2013. Source: Comprehensive Test Ban Treaty Organization, 2013.