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Moving beyond the widely used kinematic models for the deformation sources, we present a new dynamic model to describe the process of injecting magma into an existing magma reservoir. To validate this model, we derive an analytical solution and compare its results to those calculated using the Finite Element Method. A Newtonian fluid characterized by its viscosity, density, and overpressure (relative to the lithostatic value) flows through a vertical conduit, intruding into a reservoir embedded in an elastic domain, leading to an increase in reservoir pressure and time‐dependent surface deformation. We apply our injection model to Interferometric Synthetic Aperture Radar (InSAR) data from the ongoing unrest episode at Laguna del Maule (Chile) volcanic field that started in 2007. Using a grid search optimization, we minimize the misfit to the InSAR displacement data and vary the three parameters governing the analytical solution: the characteristic timescale τ P for magma propagation, the maximum injection pressure, and the inflection time when the acceleration switches from positive to negative. For a spheroid with semimajor axis a = 6200 m, semiminor axis c = 100 m, located at a depth of 4.5 km in a purely elastic half‐space, the best fit to the InSAR displacement data occurs for τ P=9.5 years and an injection pressure rising up to 11.5 MPa for 2 years. The volume flow rate increased to 1.2 m3/s for 2 years and then decreased to 0.7 m3/s in 2014. In 7.3 years, at least 187 × 106 m3 of magma was injected., Key Points Our analytical and numerical model describes viscous magma propagation into a reservoirIncreasing conduit inlet pressure and volumetric flow rate accounts for the accelerating upliftAt least 187 million cubic meters of magma with viscosity 100 MPa s was injected between 2007 and 2014

High-resolution magnetic data collected along the axis and the south flank of the Puna Ridge, the submarine extension of the East Rift Zone of Kilauea Volcano, Hawaii, aid in the interpretation of magmatic processes. Crustal magnetization varies along the crest of the Puna Ridge. Three prominent magnetization highs are located between the depths of 1500 and 2500 m. Each of the magnetization highs is associated with distinct volcanic features: a flow field on top of fissured terrain, a lava plateau, and a staircase of lava terraces. The crustal magnetization highs can be explained by the presence of these volcanic features, taking into account water depth and the size of the volcanic features and making simple assumptions about the rock magnetization. No measurements of rock magnetization have been made on Puna Ridge samples. We assume two values: 50 and 10 A/m, based on values from mid-ocean ridge basalts and the estimated ages of Puna Ridge rocks [Clague et al., 1995]. The two shallowest magnetization highs are adjacent to a landslide scarp. Lava flows overtop the scarp suggesting that a dike has been emplaced and eruptions have occurred since the landslide formed. A possible scenario is that the collapse of the flank led to dike intrusion and eruption at this location because of a reduction in the horizontal stress within the edifice. Our observations suggest that flows are starting to fill in the gap caused by the landslide to rebuild this section of the north flank.

[1] We examine mantle melting, fractional crystallization, and melt extraction beneath fast slipping, segmented oceanic transform fault systems. Three-dimensional mantle flow and thermal structures are calculated using a temperature-dependent rheology that incorporates a viscoplastic approximation for brittle deformation in the lithosphere. Thermal solutions are combined with the near-fractional, polybaric melting model of Kinzler and Grove (1992a, 1992b, 1993) to determine extents of melting, the shape of the melting regime, and major element melt composition. We investigate the mantle source region of intratransform spreading centers (ITSCs) using the melt migration approach of Sparks and Parmentier (1991) for two end-member pooling models: (1) a wide pooling region that incorporates all of the melt focused to the ITSC and (2) a narrow pooling region that assumes melt will not migrate across a transform fault or fracture zone. Assuming wide melt pooling, our model predictions can explain both the systematic crustal thickness excesses observed at intermediate and fast slipping transform faults as well as the deeper and lower extents of melting observed in the vicinity of several transform systems. Applying these techniques to the Siqueiros transform on the East Pacific Rise we find that both the viscoplastic rheology and wide melt pooling are required to explain the observed variations in gravity inferred crustal thickness. Finally, we show that mantle potential temperature Tp = 1350°C and fractional crystallization at depths of 9–15.5 km fit the majority of the major element geochemical data from the Siqueiros transform fault system.