3 SEPTEMBER 2017 UNDERGROUND NUCLEAR BOMB TEST ANALYSIS USING SEISMIC DATA WITH P/S SPECTRAL RATIO METHOD AND MOMENT TENSOR INVERSION IN PUNGGYE RI DISTRIC, NORTH KOREA

• Main Author: - NIM:12314062 , ADITYAPRABOWO
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/25026
• Institution: Institut Teknologi Bandung

<p align="justify">Punggye-ri district, North Korea, is a place that known as the North Korea Nuclear Test Site. In this area, there have been 5 underground nuclear tests recorded in the range of 2006-2016.In September 3, 2017 a seismic event was observed in this area which was suspected of being related to underground nuclear testing activities. Direct monitoring of nuclear test activities is dif&#64257;cult because the blasting occurs beneath the surface. Therefore,the monitoring of nuclear test activities must done with undirect method, such as seismic activity monitoring (Walter and Hartse, 2002). This study aims to analysis underground nuclear test using spectral ratio P/S method and moment tensor inversion and also to measure its explosive energy. The data used in this study is the seismic event data from the regional station in IRIS network on September 3, 2017 which occurred in the North Korea Nuclear Site. To calculate the spectral ratio of P/S, the regional phases determine using short time fourier transform and polarity analysis using eigen vector and eigen value. Afterwards, ISOLA was used to determine the solution of focal mechanism was determine using moment tensor inversion method . Furthermore, the calculation of explosive energy using the approach of magnitude body by Murphy (1996). The result of regional average P/S spectral ratio calculation is higher than 1 for a frequency 1-4 while the result of moment tensor was ISO part(53.5%) and CLVD (44.3%) dominated over DC part (2.2%). This result indicate event 3 September 2017 was related to underground nuclear test. In addition,the result from explosive energy calculation reaches 292.86 kilotons of TNT equivalent or 1,225 petajoules.<p align="justify"> <br />