Ridge regression particle swarm optimization (RR-PSO) is an optimization technique based on the simulation of social behavior of some animal swarm that has been successfully used in many different engineering fields. In this study, RR-PSO was used to invert Rayleigh wave phase velocity curves that extracted from ambient seismic noise records to obtain the shear velocity (Vs) profile. The optimization algorithm is relatively faster, stable and the important aspect is that can provide uncertainty information of the inversion results. In order to determine the capabilities of the RR-PSO algorithm, the synthetic simulation was carried out using both noise-free and noise-contaminated data. The validity test includes the calculation of similarity index and estimation of the model uncertainty using their standard deviation. Based on the resulted model, the convergence of RR-PSO algorithm is relatively faster, stable and adaptable to some level of noise and can provide good model estimation of the subsurface. The application of RR-PSO to the real dispersion curve data is carried out in order to determine the seismic crustal structure beneath Nusa Tenggara islands.

Currently, zeolites are widely used in various fields including horticultural, agricultural, household, industrial, water and wastewater management. Due to the increasing use of zeolites, it is estimated that the demand for zeolites will increase in the future. Therefore, it is necessary to conduct a survey to determine the potential of zeolites in an area. Campang Tiga is an area with quite a lot of potential zeolite and is exposed on the surface along with tuffs from the Lampung Formation. To estimate the potential zeolite in this area, it was carried out the Electrical Resistivity (ERT) measurements to determine the distribution and depth of the tuff layer associated with the zeolite. Measurements were made in 3 lines with an electrode spacing of 6 m using a dipole-dipole configuration. The result performs that the zeolites in the area are located at a depth of up to ∼ 10 m and are getting thicker towards the east until they reach a depth of ∼ 20 m. The results of this interpretation have been combined with the results of laboratory measurements of the resistivity value of zeolites in the area. Laboratory test results present that the zeolite resistivity value ranges from 20-300 Ωm.

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