OBJECTIVES: THE PRIMARY GOAL OF THIS STUDY IS TO CREATE A DATA ASSIMILATION FRAMEWORK USING INTERFEROMETRIC SYNTHETIC-APERTURE RADAR (INSAR) AND GPS DATA FOR SEVERAL ALEUTIAN VOLCANIC SYSTEMS (E.G. ATKA SEGUAM MAKUSHIN OKMOK WESTDAHL AND AKUTAN) TO DETECT PRECURSORS AND MAKE PROGRESS TOWARDS THE EVENTUAL GOAL OF PROVIDING ERUPTION FORECASTS IN COORDINATION WITH THE ALASKA VOLCANO OBSERVATORY (AVO). SATELLITE INSAR OBSERVATIONS DETECT VOLCANO DEFORMATION AND PROVIDE EARLY WARNING OF VOLCANIC UNREST PROVIDING CRITICAL INSIGHT INTO THE EVOLUTION OF THE UNDERLYING MAGMA SYSTEM (E.G. BIGGS ET AL. 2014). HOWEVER A QUANTITATIVE MODEL-DATA FUSION FRAMEWORK IS NECESSARY TO EFFICIENTLY UTILIZE INSAR DATA AND PROVIDE UPDATES OF VOLCANIC SYSTEMS IN NEAR-REAL TIME. THE ENSEMBLE KALMAN FILTER (ENKF) HAS PROVEN EFFECTIVE FOR COMBINING GEODETIC DATA WITH VOLCANO MODELS TO FORECAST THE EVOLUTION OF MAGMA SYSTEM STABILITY THROUGH TIME (GREGG AND PETTIJOHN 2016; ZHAN AND GREGG 2017; ZHAN ET AL. 2017). THE VOLCANO ENKF APPROACH HAS SUBSEQUENTLY BEEN ADAPTED FOR HIGH-PERFORMANCE COMPUTING (HPC) APPLICATIONS ALLOWING FOR THE INCORPORATION OF MORE SOPHISTICATED 3D MAGMA RESERVOIR MODELS. THESE RECENT ADVANCEMENTS HAVE CREATED AN EXCITING OPPORTUNITY TO DEVELOP VOLCANO-SPECIFIC MODELS TO TRACK FUTURE UNREST AND ERUPTION POTENTIAL. WE PROPOSE TO USE THE VOLCANO ENKF HPC APPROACH TO BUILD A DATA ASSIMILATION-MONITORING FRAMEWORK FOR HIGH-RISK VOLCANO SYSTEMS IN REMOTE AREAS OF THE ALEUTIAN ARC. WE WILL FOCUS OUR INVESTIGATION ON SIX VOLCANOES IN THE ALEUTIANS CLASSIFIED AS HIGH PRIORITY BY AVO: ATKA SEGUAM MAKUSHIN OKMOK WESTDAHL AND AKUTAN. GIVEN THE CHALLENGE OF COLLECTING GROUND-BASED MEASUREMENTS AT THESE SYSTEMS WE WILL FOCUS OUR EFFORTS ON OPTIMIZING THE USE OF SATELLITE INSAR DATA AND USE GPS DATA WHERE AVAILABLE. IN PARTICULAR WE PROPOSE TO ANALYZE GEODETIC OBSERVATIONS TO PRODUCE TIME SERIES SURFACE DEFORMATION DATA THAT WILL BE COMBINED WITH THERMOMECHANICAL FINITE ELEMENT MODELS FOR EACH VOLCANO TARGET. ANALYSIS OF HISTORICAL ERUPTIONS AT EACH SYSTEM WILL BE USED TO OPTIMIZE THE APPROACH AND PROVIDE HINDCASTS FOR INVESTIGATING ERUPTION PRECURSORS AND HISTORICAL STRESS THRESHOLDS. EACH MODEL WILL BE RUN FORWARD IN TIME TO PROVIDE A CURRENT SYSTEM STATUS ANALYSIS. WORKING IN COORDINATION WITH COLLEAGUES AT THE ALASKA VOLCANO OBSERVATORY THESE PRESENT-DAY OPTIMIZED MODELS WILL PROVIDE A BASIS FOR FUTURE NEAR REAL-TIME FORECASTING EFFORTS. METHODS: (1) WE WILL DEVELOP A NEW OPTIMIZED INSAR TIME SERIES WORKFLOW. HISTORICAL DATA WILL BE ANALYZED TO PROVIDE A FRAMEWORK FOR SWIFT PROCESSING OF NEW INSAR DATA. (2) WE WILL USE THE VOLCANO ENKF HPC TECHNIQUE TO ASSIMILATE UPDATED GEODETIC TIME SERIES DATA AND PROVIDE HINDCASTS . (3) WE WILL ANALYZE 3D THERMOMECHANICAL FINITE ELEMENT MODELS (GREGG ET AL. 2012 2013 2015) TO EVALUATE THE STRESS EVOLUTION OF THE SYSTEM AND INVESTIGATE ERUPTION PRECURSORS AND TRIGGERING MECHANISMS FOR HISTORICAL ERUPTIONS. (4) THE OPTIMIZED MODELS WILL ESTABLISH A PRESENT DAY BASELINE AND PROVIDE ANALYSIS OF CURRENT ACTIVITY FORECASTS AND SYSTEM STABILITY. SIGNIFICANCE TO NASA S MISSION: (1) NATURAL HAZARDS: A PRIMARY GOAL OF NASA S EARTH SCIENCE RESEARCH PROGRAM IS TO CHARACTERIZE THE DYNAMICS OF EARTH S SURFACE AND INTERIOR IMPROVING THE CAPABILITY TO ASSESS AND RESPOND TO NATURAL HAZARDS AND EXTREME EVENTS. THE PROPOSED STUDY AIMS TO ESTABLISH A MODEL-DATA FUSION TECHNIQUE TO COMBINE VOLCANO GEODYNAMIC MODELS WITH SATELLITE INSAR DATA TO INVESTIGATE ERUPTION PRECURSORS. (2) NASA EARTH OBSERVING SYSTEM DATA AND INFORMATION SYSTEM (EOSDIS): THE VOLCANOES INVESTIGATED IN THIS PROJECT WILL ADVANCE EOSDIS WHICH IN A FEW YEARS WILL PROVIDE SUB-DAILY SAR ACQUISITIONS FOR ALL MAJOR VOLCANIC CRISES. (3) NASA-ISRO: OUR PROPOSED MODEL-DATA FUSION FRAMEWORK FOR ERUPTION FORECASTING WILL PROVIDE CRITICAL TESTS BEFORE THE PROPOSED NASA-ISRO SAR MISSION GOES ONLINE.