New Details Emerge on Pakistan's First Nuclear Test Site
By David Albright, Corey Gay, and Frank Pabian
Immediately following the nuclear weapons tests conducted last May, Pakistan released detailed videotape images of their mountain test site during and after the May 28, 1998, test(s) . Analysis of those videos, together with other available open-source data such as media reports, seismic data, mapping and geologic references, and commercial satellite imagery, led to the determination of the precise geographic location, geologic setting, and operational features and layout of the 28 May 1998 nuclear test site. That analysis also exposed some of the techniques employed by the Pakistanis in their attempt to thwart overhead detection and monitoring of their nuclear test activities prior to testing. Comparison of both pre- and post-test imagery also showed the extent of some of the physical test effects, evident as recent rockslides on the mountain, that resulted from the underground detonation(s).
Locating the May 28 Test Site
The day after the initial nuclear test explosions (five simultaneous tests were claimed), Pakistan Television released terrestrial footage of the blasts. The videos showed dramatic surface disturbances, including rising yellowish-whitegreyish-white dust clouds and falling rockslides. The light-toned coloration of the dust contrasted sharply from the darker tones of the mountain moments before the test. Other than a simple reference to Baluchistan Province, no more detailed geographic locational information was initially released with those videos.
Most media reporting, both before and after the Pakistani nuclear testing, accurately located the 28 May 1998 test site as being within the Chagai District of Baluchistan Province in western Pakistan. Nonetheless, the media frequently, mistakenly, referred to a more precise location for the site as being within an oval shaped uplands area known as the Chagai Hills near the Afghan border just north of the town of Dalbandin. Such erroneous reports even claimed to have found the nuclear test site(s) in the Chagai Hills on commercial satellite imagery. However, just before the 28 May test, a Times of India report suggested that the test site was alternatively located south of the Chagai Hills in the 200 kilometer long Ras Koh range. That linear mountain range, trending north east-south west and having greater relief than the Chagai Hills, is located south of the town of Dalbandin. Shortly after the 28 May 1998 nuclear tests, a Reuters reporter provided possible coordinates for the test site, obtained via unnamed sources, that also placed the test site within the Ras Koh range southeast of Dalbandin. Final determination of the true test site location remained dependent upon post-test correlation of seismic data, other post-test media reporting, and any available terrestrial and satellite imagery.
Seismic data alone also proved inconclusive in locating the test site. Both the US Geological Survey (USGS) and the Prototype International Data Center (PIDC), the organization established to coordinate remote monitoring for the Comprehensive Test Ban Treaty Organization, placed the area of the May 28 seismic signals in a lowlands plain between the Ras Koh range and Chagai Hills east of Dalbandin. While the associated uncertainties of these estimates included at least a portion of the Ras Koh range, they did not cover any area having the topographic features shown in the Pakistani distributed videos. The preliminary seismic estimates did, however, narrow down the area of the Ras Koh range in which the site was most likely located. More importantly, the 28 May videos suggested that the test site was actually situated on the southern flank of steeply slopping mountain terrain. Given that the videos were taken at the time of the test, at 3:16 p.m. local time and the sun was directly behind the camera (as there were no shadows facing the camera), the camera had to have been looking in an easterly direction. The mountain shown rising abruptly from right to left, must, therefore, have been rising from the south. The significant break in slope at the base of the mountain was also consistent with geologic faulting.
Media reports stated that a very small population in the area of the test site was evacuated and geographical references were also provided. However, the villages mentioned in these reports could either not be found on available maps or were too far away from the area of the seismically derived coordinates to be credible.
An archival search of geologic maps and one SPOT satellite browser image (freely accessible via the Internet) narrowed down the most probable location of the test site to a mountainous area east-southeast of the seismic estimates, known as Koh Kambaran. That area was also roughly midway between the calculated seismic coordinates and those provided by Reuters. The south-western flank of that mountain was also found to be bounded by a significant geologic fault giving added assurance that this was the most promising area to begin a more detailed imagery search. Such a search, however, required the purchase of high-resolution imagery.
Due to the high-cost per area of image coverage, only a relatively small portion of a Russian KVR-1000 satellite image was obtained (covering only 25 square kilometers) that was limited only to the extreme southern flank of the Koh Kambaran mountain area. Despite having missed inclusion of the most prominent readily identifiable feature (the mountain summit) shown in the televised terrestrial videos, that image did show both the geologic fault and, more significantly, evidence of some human activity at the base of that mountain.
A Closer Look: Confirmation and Camouflage
A Russian satellite image, obtained from Spin-2, revealed a complex of roads and buildings in the northeastern corner, consistent with a small test support camp with geographic coordinates: 28 46 52N, 064 56 43E. Confirmation that these features were indeed associated with activity to support Pakistan's first nuclear test was made through correlation with additional terrestrial images taken on the ground by Pakistan Television during Prime Minister Nawaz Sharif's 19 June 1998 visit to the test site. A Pakistani media report at the time also specified that the test site which the Prime Minister visited was in the "Ras Koh mountain range in the Chagai district." The site layout consists of a small collection of buildings on an upper terrace, including the Forward Recording Site (FRS) instrumentation bunker with a single dirt road that leads to the tunnel portal. A loop-shaped road leads from the terrace down to the lower level, where the main support camp is located. An exterior view of the forward recording site's instrumentation bunker with an interior view showing what appear to be oscilloscopes (including one with a recording camera) connected with extensive input signal cabling appear on the video footage shot by Pakistan Television. Additional footage reveals a frame-capture mosaic of the tunnel portal area, illustrating how the Pakistanis used adobe structures to obscure the portal's presence from overhead observation and monitoring. Similar adobe structures were scattered throughout the site successfully giving it the general appearance of a simple hamlet. The Pakistanis also used camouflage netting, matting, and canvas to conceal the instrumentation bunker, cabling, a few other structures, along with various pieces of equipment around the site.
During the May 28 test, the relative motion in the terrestrial video of the shaking of the mountain suggested that the strongest explosion(s) most likely was directly beneath the light-toned rock-capped false summit located on the southern flank of the Koh Kamabaran massive, well within the Kuchakki volcanics, approxi mately one kilometer from the tunnel portal (geographic coordinates: 28 47 23N, 064 56 34E). This is consistent with a media report that the shot occurred 1 km inside the mountain. Another report indicated that the tests were conducted in an "M-shaped tun- nel." Such a tunnel arrangement, when seen in plain-view, could be used to support multiple nuclear tests simultaneously, with the zig-zag pattern providing assistance with closure to prevent venting of the blasts.
A comparison of an 7 April 1998 Indian IRS-1C panchromatic 5-meter resolution image (obtained from Space Imaging, Inc., subsequent to the purchase and analysis of the Russian image) with a geological map shows the relative location of the peak, and permits the identification of the likely detonation point on the geologic map. According to the surficial geologic map, the rocks located above the shot point consist of hard volcanics, such as andesites, rhyolites, or welded tuffs, similar to those found in the mesas of the US Nuclear Test Site in Nevada. Interestingly, the geological map also shows that the tunnel actually crosses the fault line. The fault line can most clearly be seen in the Indian IRS-1C satellite image.
Physical Test Effects
Many pieces of distinctively light-toned, hard capping rock on the peak were broken and dislodged during the test which resulted in significant rockslides (clearly visible in ravines located on the south side of the mountain in the 19 June 1998 post-test video frame capture of the mountain). None of those rockslides were evident on the most recent available 7 April 1998 pre-test satellite image of the mountain.
This study demonstrates how new information can be derived through the integration of data from a variety of open sources, including commercial satellite imagery, to (for the first time) accurately pin-point and describe the location and operational layout of Pakistan's first nuclear test as well as the measures taken to conceal associated test preparations. Additionally, the general geologic setting and extent of short-term physical effects of the test(s) were also determined. That new information can, in turn, provide a basis for improving the geographic accuracy of processed seismic data for the region, possibly refining yield estimates, and for verifying previous media reporting. This information also provides historical and mapping datum necessary for the planning of any future onsite inspections that may be conducted by the Comprehensive Test ban Treaty (CTBT) organization, should Pakistan accede to that treaty.
Satellite imagery is an important complement to seismic networks. Although each alone has limits, together they can greatly enhance the effectiveness of efforts to verify the CTBT.
This report is limited to information generated about the first test(s) on May 28. Analysis continues of the second test site located about 100 kilometers southwest of the first site, where another nuclear detonation occurred on May 30, 1998.
About the Authors:
David Albright, is the President of ISIS. Corey Gay is a Policy Analyst at ISIS. Frank Pabian is certified by the American Society of Photogrammetry and Remote Sensing as a "Certified Mapping Scientist, Remote Sensing," and is an imagery analysis consultant to ISIS.