Checkerboard test implementation into ionospheric tomography for SuGAr data

Available GPS data in Indonesia which coincidence with large earthquake is limited and not adequate to reconstruct a well-ionospheric tomography. Large earthquake is occur in 2004 and large GPS data is only available from Sumatra GPS Array (SuGAr). This study is intended to support ionospheric tomography for limited data by checkerboard test. Tomography result is obtained by optimizing grid size, interval, a priori models, and norm damping. The dependency to a priori model is reduce by choosing alpha value parameter (alpha=0.1). For case study, ionospheric tomography is implemented to preseismic analysis in Bengkulu earthquake at September 12, 2007 which expected to have long-term effects in the ionosphere. The result is validated by checkerboard test to shows the resolutions of ionospheric tomography.