Crustal Shear Wave Velocity Structure Using Dispersion of Rayleigh Wave Beneath Sumatra Stations

The structure of the earth's crust is a fundamental and very important topic in seismology, because the crustal structure can be used as initial information to study the surface conditions of an area. One method to determine the structure of the earth's crustal layers is by analyzing the dispersion of surface waves, because surface waves are very sensitive to S waves. The shear wave velocity as a result of Rayleigh wave velocity inversion can provide the information of the subsurface material properties in the earth that can be study the structure of the earth's crust. The inversion results using the SVAL program can provide the Rayleigh wave dispersion curve with group velocity which shows the station on the island of Sumatra is higher than the velocity on the island of Nias. The structure beneath the island of Sumatera was formed earlier than the island of Nias. The thickness of the crust varies in the Sumatra region, the thickness of the crust on the island of Sumatra (BKNI, LHMI, MNAI and PMBI) is 28 km and 33 km. Specifically on the island of Nias, the thickness of the crust is 19 km. S-wave velocity in the crust is 3.1 km/s to 3.7 km/s.