Identifikasi struktur bawah permukaan daerah Yogyakarta menggunakan metode Energy Spectral Analysis Multi Window Test (ESA_MWT) dan Multiscale Second Vertical Derivative (MS-SVD) data gravitasi = Yogyakarta regional structure subsurface structural identification using Energy Spectral Analysis Multi Window Test (ESA-MWT) and Multiscale Second Vertical Derivative (MS-SVD) gravitation data abstract