Comparison of India's and Pakinstan's nuclear tests and the 30 May, 1998 Afghanistan earthquake

The four figures below show the first Indian nuclear test of 11 May 1998, the first Pakistani test of 28 May 1998, the predicted arrival time for the second Pakistani test of 30 May 1998 and the Ms 6.9 Afghanistan earthquake of 30 May 1998. All are plotted with the same amplitude and time scale. The amplitude of the waveforms in the final figure showing the Afghanistan earthquake plot off scale because the scale was normalized to the Indian nuclear test.

Frequently Asked Question

Q: Did the Pakistani nuclear test cause the Ms 6.9 Afghanistan earthquake on May 30, 1998?

A: No. The Afghanistan earthquake occured 32 minutes BEFORE the Pakistan nuclear test on the same day. The earthquake is located over 700 km away from the Indian and Pakistani nuclear test sites, in a region known for earthquakes. The same region suffered an Ms 6.1 earthquake on February 4, 1998.

India's 11 May 1998 nuclear test

Station Channel Arrival Time Phase Delta Azimuth mb SNR
AML BHZ 5/11/1998 10:17:16.040 P 15.142 186.60 5.81 204.41
UCH BHZ 5/11/1998 10:17:18.425 P 15.322 189.31 5.47 137.99
AAK BHZ 5/11/1998 10:17:24.023 P 15.720 189.02 5.43 61.87
KBK BHZ 5/11/1998 10:17:25.004 P 15.799 190.47 5.48 19.50
CHM BHZ 5/11/1998 10:17:28.874 P 16.111 189.64 5.69 37.11
TKM2 BHZ 5/11/1998 10:17:29.222 P 16.153 192.36 5.50 62.52
USP BHZ 5/11/1998 10:17:31.191 P 16.347 188.69 5.07 27.60

India test magnitude based on REB location using 7 stations is mb = 5.49

Pakistan's 28 May 1998 nuclear test

Station Channel Arrival Time Phase Delta Azimuth mb SNR
AAK BHZ 5/28/1998 10:20:01.026 P 15.776 213.08 5.37 47.74
CHM BHZ 5/28/1998 10:20:05.688 P 16.184 213.11 5.33 21.83
TKM2 BHZ 5/28/1998 10:20:09.431 P 16.469 215.58 5.18 54.23

Pakistan test magnitude based on QED location using 3 stations is mb = 5.29

Indian test magnitude based on REB location using same 3 stations which recorded the Pakistan test of 5/28/1998 is mb = 5.54

The second Pakistan test was obscured by aftershocks from the Ms 6.9 earthquake which occured about 30 minutes before the second test.

Examination of the waveform data, based on the QED location, shows no observable body waves at the predicted arrival times. Using the first Pakistani explosion for calibration, the amplitude of the second Pakistani explosion is at least a factor of four smaller (0.6 magnitude units) for it not to be observed in the aftershock data. Please click on the images below for an enlarged version.

KNET recording of India nuclear test KNET recording of first Pakistan nuclear test

KNET recording of second Pakistan nuclear test KNET recording of Afghanistan earthquake

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URL: http://eqinfo.ucsd.edu/special_events/nuclear_tests/comparison.php [Last updated: 2010-11-23 (327) 23:01:44 UTC]