THE MIGRATION OF MAGMA (IMPULSE) WITHIN A VOLCANO PRODUCES A DEFORMATION SIGNATURE (RESPONSE) AT THE EARTH S SURFACE. INVERSE MODELS OF GEODETIC DATA ESTIMATE KEY PARAMETERS THAT CHARACTERIZE THIS MIGRATION. THIS PROJECT WILL ADVANCE THE NUMERICAL MODELING METHODS THAT QUANTIFY MAGMA MIGRATION WITHIN THE NON-UNIFORM RHEOLOGICAL STRUCTURE AND STRESS FIELD OF AN ACTIVE VOLCANO. BASED ON CUSTOMARY ANALYTICAL POINT-SOURCE ANALYSES TIME-DEPENDENT VOLCANO DEFORMATION LINEARLY TRACKS MAGMA INTRUSION INTO A SPHERICAL CHAMBER. THIS PROJECT PROPOSES AN ALTERNATIVE INTERPRETATION THAT TIME-DEPENDENT VOLCANO DEFORMATION IS THE NET RESULT OF DISCRETE PULSES OF MAGMA INTRUSION THAT EXCITE SUBSEQUENT VISCOELASTIC RELAXATION OF THE THERMALLY-WEAKENED DOMAIN THAT HOSTS AN ARBITRARILYSHAPED CHAMBER. ACCURATE DESCRIPTIONS OF THE TRANSIENT MAGMA LOADING AND EVOLVING STRESS FIELDS ARE NECESSARY TO RELIABLY PREDICT DIKE PROPAGATION -THE PROCESS THAT TRANSPORTS MAGMA TO THE EARTH S SURFACE. THE OVERARCHING GOAL OF THIS PROJECT IS TO IMPROVE INSAR INTERPRETATIONS OF ACTIVE VOLCANOES BY ADVANCING THE MODELING METHODS THAT SIMULATE AND CHARACTERIZE MAGMA MIGRATION WITHIN THE COMPLEX STRUCTURE OF RHEOLOGICAL PROPERTIES AND NON-UNIFORM STRESS FIELD OF AN ACTIVE VOLCANO. THIS GOAL ADDRESSES NASA SMD S INTEREST IN CHARACTERIZING THE DYNAMICS OF THE EARTH SURFACE AND INTERIOR AND FORMS THE SCIENTIFIC BASIS FOR THE ASSESSMENT AND MITIGATION OF NATURAL HAZARDS. THIS PROJECT WILL DEVELOP NUMERICAL AND COMPUTATIONAL TOOLS TO ESTIMATE PARAMETERS AND UNCERTAINTIES THAT DESCRIBE THE SHAPE OF THE MAGMA CHAMBER THE HISTORY OF MAGMA FLUX AND SURROUNDING RHEOLOGIC STRUCTURE BASED ON INSAR DATA THAT SPAN THE 1997-2008 ERUPTION CYCLE FOR OKMOK VOLCANO ALASKA. MODELS HAVING FIDELITY TO THE RESULTING DOMAINS AND GEOMETRIC CONFIGURATIONS WILL HOST SIMULATIONS OF DIKE PROPAGATION. THE PROJECT INCLUDES THREE PRIMARY OBJECTIVES. SUCCESSFUL COMPLETION OF THESE OBJECTIVES WILL PROVIDE SOPHISTICATED NUMERICAL TOOLS FOR INTERPRETING ANTICIPATED DATA STREAMS FROM THE UPCOMING NISAR MISSION. OBJECTIVE A: CHARACTERIZING THE MAGMA CHAMBER SHAPE WITH SPHERICAL HARMONICS. AN ASSEMBLY OF SPHERICAL HARMONICS CAN REPRESENT AN ARBITRARY 3D SOLID. RATHER THAN ASSUME A PARTICULAR GEOMETRY OF THE CHAMBER THIS PROJECT WILL TREAT THE HARMONIC SCALING COEFFICIENTS AS CALIBRATION PARAMETERS AND LET THE DATA DETERMINE THE GEOMETRY OF THE CHAMBER WHICH NEED NOT BE LIMITED TO RELATIVELY SIMPLE SHAPES (SPHERE ELLIPSOID DIKE OR SILL). THE GEOMETRIC CHARACTERIZATION OF THE MAGMA CHAMBER IN TERMS OF SHAPE AND LOCATION WILL BE CALIBRATED TO CO-ERUPTION INSAR DATA HAVING A LARGE SIGNAL-TO-NOISE RATIO AND IS ASSUMED TO REPRESENT ELASTIC DEFORMATION. DEFORMATION WILL BE SIMULATED USING FINITE ELEMENT MODELS (FEMS). RESULTING MAGMA CHAMBER GEOMETRY WILL BE USED IN MODELS NECESSARY TO ACHIEVE OBJECTIVES B AND C. OBJECTIVE B: QUANTIFY HOW A MAGMA INTRUSION IS MODULATED BY THE VISCOELASTIC HOSTING DOMAIN TO PRODUCE TRANSIENT DEFORMATION. THIS PROJECT WILL DEVELOP NEW FEM-BASED NONLINEAR INVERSE ANALYSES OF INSAR DATA TO ESTIMATE PARAMETERS AND UNCERTAINTIES FOR THE LOCATION NUMBER AND TIMING OF MAGMA IMPULSES AND THE TEMPERATURE-DEPENDENT RHEOLOGIC PROPERTIES OF THE DOMAIN THAT HOSTS THE MAGMA INTRUSION. OBJECTIVE C: QUANTIFY DIKE PROPAGATION WITHIN THE STRUCTURALLY COMPLEX DOMAIN OF AN ACTIVE VOLCANO. DIKE PROPAGATION IS A FUNCTION OF THE MAGMA FLUX COMPRESSIBILITY AND VISCOSITY; THE STRENGTH OF THE ROCK; AND THE STRESS FIELD. THIS PROJECT WILL USE FEMS TO SIMULATE FLUID-SOLID COUPLING THAT TRACKS THE PROPAGATION OF DIKES WITHIN THE DOMAIN TRANSIENT STRESS FIELDS AND MAGMA LOADING SCHEDULE RESULTING FROM OBJECTIVE B.