Pre-eruption Deformation Prior to 2018 Eruption of Anak Krakatau Volcano

Abstract Anak Krakatau is an active volcano situtated in Sunda Strait between Sumatera and Java that is frequently erupts. In 2018, Anak Krakatau eruupted where its eruptions destroys its western and south western flank that created a tsunami that swept across western Banten Province and southern Lampung Province, killed hundreds of casualties and destroyed homes in the shorelines. With the use of Differential InSAR analysis, we observe the dynamics of activity of Anak Krakatau starting from January 2018 until December 2019. To observe the unrest of Anak Krakatau prior and after the eruption, we’re using radar satellite imagery from Sentinel 1 from European Space Agency with temporal baseline every 12 days with total of 60 images being used. These images then processed using differential Interferometric Synthetic Aperture Radar (DInSAR) method and then being analysed the ups and downs patterns between 12-day-pairs. From our observation, deformation signals appeared in some interferogram pairs prior to eruption in December 2018. We also find that the activity of Anak Krakatau still rising after the eruption of 2018, showed by the upward trend that happened in the point samples near the vent. The graph analysed from InSAR pairs also show that there is a pattern of inflation and subsidence that shows the activity of Anak Krakatau. It is suggested that the supply from magma chamber played a role in the uplift of Anak Krakatau that happened in the time of our observation. We conclude that the activity of Anak Krakatau was detected prior the eruption and still not decline and will going to be active in some more time.