ANALISIS DATA TILTMETER DENGAN METODE FAST FOURIER TRANSFORM (FFT) UNTUK MENENTUKAN PERIODISASI DEFORMASI LAVA 56” GUNUNG MERAPI

Abstract

Merapi vulcano is one of the most active and dangerous vulcanoes in Indonesia. Merapi vulcano has a special eruption type,it’s know as Merapi type. When have eruption, most of magma flow from magma dome to surface be lava or another material. Process of magma climbing and pressure increase cause changing of Merapi Volcano body’s, pressure increasingly in a deep to surface will give deformation effect to Merapi Vulcano body’s. One of research to know deformasi changing is use tiltmeter. From tiltmeter data can knowed changing of form Merapi vulcano body’s in a radial and tangensial direction. Use a Fast Fourier Transform ( FFT ) analysis can knowed dominant frequency from deformasi activity from Merapi Vulcano. Division of history into periodisity of Merapi vulcano can knowed use periodogram. This research had did between February 27th until June 30th 2008. Tiltmeter data which recorded at this time divided be six groups. This research shows that had different times for each deformation observation. Every had increasing of deformation activity, usually followed by increasing of temperature. Increasing of rain intensity make increasing of deformation value. Highest deformation value on Febuary 27th until june 30th 2008 are 145,2 μrad ( radial ) dan 130,7 μrad (tangensial).