washington two minor tremor detect saturday near north korea nuclear test site probably aftershocks country massive nuclear test early september u.s. geological survey official say aftershocks magnitude 2.9 2.4 detect 0613 0640 gmt 1:13 a.m. 1:40 a.m. est respectively say usgs lassina zerbo executive secretary vienna-based comprehensive nuclear-test-ban treaty organization tweet zerbo say analysts confirm activity tectonic origin usgs official say tremor vicinity punggye-ri nuclear test site north korea conduct sixth large underground nuclear test sept. 3. probably relaxation events sixth nuclear test official say large nuclear test move earth crust around area take fully subside since sixth nuclear test pyongyang say september test h-bomb experts estimate 10 time powerful u.s. atomic bomb drop hiroshima 1945. series quake since prompt experts observers suspect test might damage mountainous location site northwest tip north korea country nuclear test conduct south korea spy agency tell south korean lawmakers october north korea might ready two tunnel site north korea hint next nuclear test could grind u.s. president donald trump warn september unite state would totally destroy north korea threaten america another possible obstacle north korea use punggye-ri test nearby active volcano mount paektu north koreans consider sacred site last eruption 1903 experts debate whether nuclear test could trigger another north korea official media report saturday national leader kim jong un scale mount paektu senior military officials emphasize military vision completion country nuclear force kim declare nuclear force complete test north korea large ever intercontinental ballistic missile last month experts say put america within range aftershocks likely september test detect north korea nuclear site usgs