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is taken, the major powers are averaging a This convention for aggregating and pre- Table 6: Percentage of All Earthquakes nuclear test every 7.3 days. The yearly _ senting the data in percentage values within (M>=5.8) after US and French Above- average in the 1960s was 56; in the 1970s it blocks of latitude and longitude, is used Ground Nuclear Tests, Pacific Ocean, was 47 tests; and in the 1980s, 47 tests. throughout this paper. 1946 to 1975 (five-day period) But the period of July 1985 to February These area blocks or zones of latitude ea , and 1987 was the self-imposed test ban by the and longitude received nearly 56% of all ts aan i w USSR, so the 1990s should show the yearly the Earth's quakes of M>=5.8 from 1900 to i . 1948-1 1288: level rise to above 50 again as they try to 1949, for a total of 1,935 earthquakes. By L : 278 431 1250 make up for lost ground. comparison, all other blocks of latitude and : » on ae “a Perhaps the only hope on this nuclear longitude each receive less than 1% of all : 3.36 8.75 4.17 testing path is the attempt to limit nuclear earthquakes. This established pattern of — — i bees tests to | KT with a view to total elimina- earthquakes of M>=5.8, with highlighted : = esi aa tion. The Soviets emphasised a goal of zones of high frequency occurrence on a ima, Peru: 126 3.07 : immediate cessation of all nuclear tests, global scale between 1900 and 1949, will = 4 pf while the Americans stressed the need to act as a control against which we can com- ico: 2.22 429 improve verification capabilities and the _ pare the patterns of earthquakes that follow ar Ps need to continue testing in the absence of nuclear testing. All such earthquakes were W. Alaska: 0.81 1.23 significant reductions in offensive nuclear recorded either on the day of the test or | “omar: 088 bs, weapons. within the four days afterward, for a five- | 0.88 2.45 In 1988, each side visited the other side's day period. : ee pat nuclear test site to monitor an underground ico: 3.07 1.84 nuclear explosion. The idea was to make Atmospheric (Above-Ground) Nuclear Sida el yd sure that both sides can verify whether a Testing sind - 0.47 test yields more or less than 150 KT. The The first area to consider is the Pacific Soviets prove accuracy by their preferred Ocean. The US tests here totalled 106 and _ nine tests at Christmas Island (1.7°N Lat, monitoring method, which counts seismic were conducted from 1946 through 1962. 157°W Long). Twelve British tests were units such as those used in monitoring The principal sites are listed below: conducted in Australia from 1952 to 1957. earthquakes. In the American method, an [7abje 5. Since 1962, all British tests have been electrical cable must be placed within 10 to underground at the USA Nevada test site. 15 metres of the blast. ’ Only the Christmas Island tests were exam- Se tees = ined here, but, once again, familiar terms Nuclear Testing and Earthquake eo, aa emerge. See Table 7. heer —s be Table 7: Percentage of All Earthquakes The distribution of all earthquakes of (>= A) after British Abowe-Ground M>=5.8 between 1900 through 1949 clear- When we review the earthquake data, the Nuclear Tests, Pacific Ocean, ly reflects the boundaries of the 11 major following areas emerge as receiving more 1952 to 1957 (five-day period) tectonic plate zones. All such earthquakes _ than their share of the M>=5.8 carthquakes. i s i were located in zones or blocks of 10 Hardest hit following USA Pacific tests, —e degrees of latitude and 10 degrees of longi- relative to the pattern prior to 1950, were S. Mexico: ; co 20.00 tude, to give frequency and per-cent distri- the blocks of latitude and longitude encom- | Smao™.sveame™ A butions on a global scale. The highest per passing Sakhalin Island, the Aleutian cent is the Southern Philippines block at Islands, Peru, Bolivia, Central America, From 1951 until 1963, the USA tested 3.95%, having recorded 135 earthquakes of Western Samoa, Vanuatu, Baja, California, 100 times above ground at the Nevada test M>=5.8 during the period. Japan, in the Hawaii and Japan. site. When these test dates are matched Hokkaido area, is next at 3.07%, with 105 French testing in the South Pacific cov- with earthquakes of M>=5.8 within a five- such earthquakes. ered years 1966 through 1974 when they day period, the following areas show a Table 4, below, identifies the major conducted 44 atmospheric tests, 39 over higher-than-normal! share of such earth- zones of high earthquake frequency, in Mururoa Atoll and five over Fagataufa quakes compared to the 1900-1950 period: some cases combining the values for adja- Atoll. The earthquake pattern after the Table 8. Percentage of All Earthquakes cent blocks of latitude and longitude. French South Pacific testing is somewhat (M>=5.8) after USA Above-Ground different, and the zones of high frequency Nuclear Tests in Nevada, 1951 to 1963 Table 4: Zones of High Earthquake earthquakes following these French tests (five-day period) Frequency (M>=5.8), 1900 to 1949 were Western Samoa, Fiji, the Solomon = 2900-1 us, U1 leas EE ex oem Lc.) Islands, the Alaska Panhandle, and the area | gmadecW, Samoa & . Number of Combinedno. %of Ai | between the Kamchatka Peninsula and | Vanuau: ave = Eanh- of Blocks of Ean | Aleutian Islands. Interestingly, these | Samcnas*/Aeutar's= sao Location ______quakes Latand long quakes regions of high carthquake activity follow- | Solomon Is.: 8.22 emery se bey — : (239% | ing Pacific nuclear testing are all confined Japanese isiands: 310 4 som | to the Pacific Ring of Fire, a zone of earth- The Soviet above-ground testing Cc 1S. ico: 5.99% . . ‘ Cuitenichepess te 7 sex | quakes and volcanoes that circles the entire involved 166 tests from 1949 to 1962. Philippines: 187 2 5.47% Pacific Ocean. These data are summarised About 70% of the known Soviet tests have ara Slims a zom | inTable6. occurred at their two main sites near New Zealand: 3 a 1.25% British tests in the Pacific Ocean covered Semipalatinsk in eastern Kazakhstan S. Greece, W, Turkey: 42 1 123% the period 1957 to 1958 and involved only (50%), and on the island of Novaya From 1951 until 1963, the USA tested 100 times above ground at the Nevada test site. When these test dates are matched with earthquakes of M>=5.8 within a five- day period, the following areas show a higher-than-normal share of such earth- quakes compared to the 1900-1950 period: Table 8. Percentage of All Earthquakes (M>=5.8) after USA Above-Ground Nuclear Tests in Nevada, 1951 to 1963 (five-day period) 1900-1 ys, KermadecW. Samoa & Vanuatu: 16.05 Kamehatka/Alautian Is.: 10,82 Taiwan: 5.60 Solomon Is. $.22 Table 4: Zones of High Earthquake Frequency (M>=5.8), 1900 to 1949 (1 block = 10° of Lat. x 10° of Long.) of All Number of Combined no. Eanh- of Blocks of Indonesia. New Guinea: 424 7 12.39% Vanvatu, Fiji, Tonga: 377 5 41.03% Japanese isiands: 310 4 9.07% Cont. Amer... Mexico: 205 4 5.99% Chile, Peru, N. Argent: 204 s 5.96% Philippines: 187 2 S.47% Taiwan: 74 1 216% N. India, Pakistan: 69 1 2.02% Naw Zealand: 43 3a 1.25% S. Groeca, W, Turkey: 42 1 123% 16.05 10,82 $.60 $5.22 11,61 4.48 2.16 298 The Soviet above-ground testing involved 166 tests from 1949 to 1962. About 70% of the known Soviet tests have occurred at their two main sites near Semipalatinsk in eastern Kazakhstan (50%), and on the island of Novaya NEXUS ¢ 13 OCTOBER - NOVEMBER 1995