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Inflation of viscous magma intrusions in Earth's shallow crust often induces strain and fracturing within heterogeneous host rocks and dome‐shaped ground deformation. Most geodetic models nevertheless consider homogeneous, isotropic, and linear‐elastic media wherein stress patterns indicate the potential for failure, but without simulating actual fracturing. We present a two‐dimensional Discrete Element Method (DEM) application to simulate magma recharge in a pre‐existing laccolith intrusion. In DEM models, fractures can propagate during simulations. We systematically investigate the effect of the host rock toughness (resistance to fracturing), stiffness (resistance to deformation) and the intrusion depth, on intrusion‐induced stress, strain, displacement and spatial fracture distribution. Our results show that the spatial fracture distribution varies between two end‐members: (a) for high stiffness or low toughness host rock or a shallow intrusion: extensive cracking, multiple vertical surface fractures propagating downward and two inward‐dipping highly cracked shear zones that connect the intrusion tip with the surface; and (b) for low stiffness or high toughness host rock or a deeper intrusion: limited cracking, one central vertical fracture initiated at the surface, and two inward‐dipping fractures at the intrusion tips. Abrupt increases in surface displacement magnitude occur in response to fracturing, even at constant magma injection rates. Our modeling application provides a novel approach to considering host rock mechanical strength and fracturing during viscous magma intrusion and associated dome‐shaped ground deformation, with important implications for interpreting geodetic signals at active volcanoes and the exploitation of geothermal reservoirs and mineral deposits. Plain Language Summary: Most viscous magmas are stored and solidified in the upper 1–2 km of Earth's crust and rarely reach the surface to produce explosive volcanic eruptions. At such shallow depths, these viscous magmas often form intrusions with a flat base and dome‐shaped roof, or "laccoliths." To accommodate the emplaced volume, the deformation of the host rock produces dome‐shaped ground uplift at the surface. Geological and geophysical observations show that laccolith emplacement often coincides with intense host rock fracturing. However, most of the numerical laccolith emplacement models ignore that fracturing and severely simplify the mechanical response of the host rock. To assess the effect of host rock fracturing on ground deformation, we designed a two‐dimensional Discrete Element Method (DEM) application, which can simulate the fracturing of the host rock during magma injection. We found that varying the strength of the host rock and/or the intrusion depth controls the spatial distribution of fracturing and magnitude of the ground uplift. Our results help to understand complex interplays between the depth of magma injection and the mechanical properties of host rocks, and to improve the modeling tools used to routinely monitor magmatic activity. Key Points: We present a two‐dimensional Discrete Element Method model that simulates host rock fracturing during the inflation of a magmatic laccolithThe host rock toughness and stiffness along with source depth control spatial fracture distribution between two end‐membersAt a constant injection rate, the vertical displacement maximum and lateral extent show sudden changes in response to host rock fracturing [ABSTRACT FROM AUTHOR]

Recent geodetic data has clearly imaged significant contraction of rift zones during effusive eruptions, which is attributed to deformation of active, elongated feeders, challenging the rigid conduit paradigm. In this work we develop a physical model to understand the impact of conduit deformation on the eruptive dynamics. Numerical calculations show that magma overpressure increases the width of the conduit, resulting in higher discharge rates than would be expected from the rigid case. At the same time, conduits with high aspect ratio, have larger compressibility and can store significant amount of magma, thereby acting as secondary reservoirs. The net result is that rift zones can maintain high fluxes over prolonged periods of time, leading to large volume eruptions and biasing magma compressibility estimates. We apply our findings to the 2018 Kīlauea eruption where episodic collapse of the summit led to pressure pulses that propagated down‐rift and that were recorded by both tiltmeters and peaks in the effusion rates. Inversion of the data indicates a conduit with a height of 700–800 m and a maximum opening of 4 m, located at a depth of 2.5 km in the Upper East Rift Zone, becoming shallower in the Puʻu ʻŌʻō region and propagating sub‐horizontally in the Middle and Lower East Rift Zone. Based on these properties we infer that up to 30% of the erupted volume can be attributed to magma stored in the rift zone. In agreement with recent studies, we find that magma over‐pressure was low at the end of the 2018 eruption. Plain Language Summary: Deformation of the volcanic edifice shows a contraction of the conduits feeding eruptions. We have developed a physical model to understand how such deformation affects the amount of magma extruded and for how long the eruption will last. The results of the model indicate that elastic conduit deformation allows for larger volumes of magma to surface more quickly, compared to cases where the conduit behaves rigidly. One important finding was that elastic conduits act as secondary magma reservoirs. We applied the model to estimate the properties of the storage and transport system of the 2018 Kīlauea eruption. We found that the conduit had a height of about 750 m and a maximum opening of 4 m. The conduit is located at a depth of about 2.5 km in the Upper East Rift Zone, becoming shallower in the Pu'u 'Ō'ō region and propagating sub‐horizontally in the Middle and Lower East Rift Zone. As much as 30% of the total erupted volume could have originated from the conduit itself. Indeed, the pressure that drove the flow of the magma was low at the end of the eruption. Key Points: Geodetic data show significant deformation of rift zones during eruptionsA physical model of elastic conduit is derived to understand deformation effects on eruption dynamicsThe model is applied to 2018 Kīlauea eruption to invert the parameters of its plumbing system [ABSTRACT FROM AUTHOR]

The ever‐increasing amount of Synthetic Aperture Radar (SAR) data motivates the development of automatic processing chains to fully exploit the opportunities offered by these large databases. The Synthetic Aperture Radar Interferometry (InSAR) Mass processing Toolbox for Multidimensional time series is an optimized tool to automatically download SAR data, select the interferometric pairs, perform the interferometric mass processing, compute the geocoded deformation maps, invert and display the velocity maps and the 2D time series on a web page updated incrementally as soon as a new image is available. New challenges relate to data management and processing load. We address them through methodological improvements dedicated to optimizing the InSAR pair selection. The proposed algorithm narrows the classical selection based on the shortest temporal and spatial baselines thanks to a coherence proxy and balances the use of each image as Primary and Secondary images thanks to graph theory methods. We apply the processing to three volcanic areas characterized with different climate, vegetation, and deformation characteristics: the Virunga Volcanic Province (DR Congo), the Reunion Island (France), and the Domuyo and Laguna del Maule area (Chile‐Argentina border). Compared to pair selection based solely on baseline criteria, this new tool produces similar velocity maps while reducing the total number of computed differential InSAR interferograms by up to 75%, which drastically reduces the computation time. The optimization also allows to reduce the influence of DEM errors and atmospheric phase screen, which increase the signal‐to‐noise ratio of the inverted displacement time series. Plain Language Summary: Development of satellite remote sensing greatly helps to mitigate natural hazard in remote or dangerous areas like volcano‐tectonic regions or landslide‐prone regions. In particular, Synthetic Aperture Radar Interferometry (InSAR) offers the possibility to measure ground surface displacements with millimeter resolution. Several methods exist to benefit from the large amount of data to perform time series of ground deformation with sub‐centimeter resolution. However, the ever‐increasing number of available images poses new challenges (e.g., to process the large amount of data, to manage large databases and to extract useful information in near‐real time for operative purposes). Mass processing Toolbox for Multidimensional time series (MasTer) is a fully automatic tool able to provide updated velocity maps and displacement time series resulting from the processing of satellites radar images, which are regularly acquired by space agencies. Hereby, we present a methodological development to speed up the processing and improve the signal‐to‐noise ratio of the obtained ground deformation time series. This is achieved by optimizing the InSAR pair selection. By also reducing the storage space and raw‐memory requirements, it allows processing longer time series with the same computational infrastructure. The proposed algorithm, written in Python, is included in the MasTer toolbox, though it can easily be adapted for other time series software. Key Points: Proposed optimized pair selection improves Synthetic Aperture Radar Interferometry time series quality while reducing computation time and memory requirementsProposed coherence proxy allows pair and image rejection without computing the interferogramsAlgorithm written in Python is used for automatic processing with Mass processing Toolbox for Multidimensional time seriestoolbox and applicable to other time series software [ABSTRACT FROM AUTHOR]

Tectonic, hydrological and industrial processes coexist in the dynamic natural environments. However, our knowledge of ground deformation associated with tectonic, hydrological and anthropogenic processes and their interactions remains limited. California represents a natural laboratory that hosts the San Andreas fault system, Central Valley and other aquifer systems, and extensive human extraction of natural resources. The attendant multi‐scale ground deformation that has been mapped using Copernicus Sentinel‐1 Synthetic Aperture Radar (SAR)‐satellite constellation from four ascending and five descending tracks during 2015–2019. We consider the secular horizontal surface velocities and strain rates, constrained from GNSS measurements and tectonic models, as proxies for tectonic processes, and seasonal displacement amplitudes from interferometric SAR (InSAR) time series as proxies for hydrological processes. We synergize 23 types of multidisciplinary datasets, including ground deformation, sedimentary basins, precipitation, soil moisture, topography, and hydrocarbon production fields, using a machine learning algorithm–random forest, and we succeed in predicting 86%–95% of the representative data sets. High strain rates along the SAF system mainly occur in areas with a low‐to‐moderate vegetation fraction (∼0.3), suggesting a correlation of rough/high‐relief coastal range morphology and topography with the active faulting, seasonal and orographic rainfall, and vegetation growth. Linear discontinuities in the long‐term, seasonal amplitude and phase of the surface displacement fields coincide with some fault strands, the boundary zone between the sediment‐fill Central Valley and bedrock‐dominated Sierra Nevada, and the margins of the inelastically deforming aquifer in the San Joaquin Valley, suggesting groundwater flow interruptions, contrasting elastic properties, and heterogeneous hydrological units. Plain Language Summary: Although scientific advances have been achieved in every individual geoscience discipline with more extensive and accurate observations and more robust models, our knowledge of the Earth complexity remains limited. The tectonic, hydrological and anthropogenic processes interact in the highly populous California, which have contributed to multi‐scale ground deformation. Here we rely on remotely sensed ground deformation products and locations of oil and gas fields as proxies for tectonic, hydrological and anthropogenic processes. The training model of the random forest algorithm has a good performance in predicting the representative multidisciplinary datasets and reveals their intrinsic similarities and relative importance in the predictions. We also note compelling spatial correlation between the long‐term and seasonal displacement discontinuities, the high‐strain‐rate fault zones, and a narrow range of vegetation fraction, as well as the margins of the heterogeneous structures. Key Points: Discontinuities in the long‐term, seasonal amplitude and phase of geodetically measured displacement fields coincide with fault strandsThe belt of high strain rate is characterized by the low‐to‐moderate vegetation fractionPhase discontinuities in seasonal displacement occur near the transition between sedimentary basins and consolidated ranges [ABSTRACT FROM AUTHOR]

Improved understanding of the impact of crystal mush rheology on the response of magma chambers to magmatic events is critical for better understanding crustal igneous systems with abundant crystals. In this study, we extend an earlier model by Liao et al. (2018); https://doi.org/10.1029/2018jb015985 which considers the mechanical response of a magma chamber with poroelastic crystal mush, by including poroviscoelastic rheology of crystal mush. We find that the coexistence of the two mechanisms of poroelastic diffusion and viscoelastic relaxation causes the magma chamber to react to a magma injection event with more complex time‐dependent behaviors. Specifically, we find that the system's short‐term evolution is dominated by the poroelastic diffusion process, while its long‐term evolution is dominated by the viscoelastic relaxation process. We identify two post‐injection timescales that represent these two stages and examine their relation to the material properties of the system. We find that better constraints on the poroelastic diffusion time are more important for the potential interpretation of surface deformation using the model. Key Points: Features of magma chamber deformation with poroviscoealstic crystal mush are examined using a mechanical modelCoexistence of poroelastic diffusion and viscoelastic relaxation causes non‐monotonous evolution in pressure, stress, and magma transportThe evolution of magma chamber is described by two characteristic time scales depending on the material properties [ABSTRACT FROM AUTHOR]

We have modeled the fast dike intrusion that started on 24 December 2018 at Mount Etna. The intrusion was accompanied by an intense seismicity swarm that also continued the following day. Since previous studies did not detail the overall chain of events in time during the magma ascent, here we propose a combined analytical and FEM modeling of all available continuous deformation data, focusing on the signals over 2 days (24–25 December) when the continuous deformation networks recorded clear variations directly related to the dike ascent. High‐rate GPS enabled obtaining an early and reliable source model. Borehole instruments (strainmeters and tiltmeters) highlighted clear variations, starting about 1 hr before those recorded by GPS, and moreover, made it possible to improve the dike ascent modeling. In particular, our continuous deformation data clearly revealed not one but two dikes and showed how they evolved in time. We inferred one dike that began propagating in the first kilometer above sea level, continued to rise with a maximum opening of 1.9 m and increased its horizontal dimension until reaching the ground surface. Soon after, continuous deformation networks revealed a new elongated intrusion in the southern flank, matching the south shifted position of the seismic swarm. This second dike, with a thicker opening of 4.9 m, started from a depth of about −3 km (below sea level) but did not reach the ground surface. This proposed multiparametric modeling of continuous deformation data has therefore enabled disentangling the complexity of the real volcanic processes. Key Points: Imaging multidisciplinary continuous deformation data to improve dike ascent modelingDetailed temporal model of the 2018 intrusion at Etna volcano [ABSTRACT FROM AUTHOR]

Fiber‐optic sensing is emerging as a superior means for distributed strain sensing of the subsurface. The ability of an embedded fiber‐optic cable to capture accurate strain profiles depends on the degree of rigid mechanical coupling between the ground and the cable. However, a current challenge in this field is to determine the actual level of ground deformation from strain signatures sensed by the cable deployed in the subsurface; addressing this issue has been hampered by the lack of suitable theoretical methods. Here we propose a two‐step ground‐cable coupling evaluation procedure, whereby we develop analytical formulations to quantify the interaction and interface shear transfer of a ground‐borehole‐cable system. We constrain key model parameters using a data set acquired with a fiber optics‐instrumented borehole for monitoring groundwater‐related sediment compaction. Extensive parametric analyses reveal that increasing the backfill modulus and cable gauge length or decreasing the borehole radius and cable stiffness can improve the quality of strain transferred to the cable from the ground; the effect of ground properties is comparably insignificant. Further, we develop design charts and tables at designated transfer thresholds to facilitate the development and field deployment of fiber sensing elements. Taken together, the theoretical quantification of ground‐cable coupling should improve the state‐of‐the‐art performance of distributed fiber‐optic strain sensing for subsurface ground movements detection and monitoring. Key Points: A new definition of ground‐cable coupling allows determining actual levels of ground deformation from fiber‐optic (FO) strain measurementsExtensive parametric analyses reveal effects of ground, borehole, backfill, and cable properties on ground‐to‐cable strain transfer qualityWe develop design charts and tables at designated transfer thresholds to facilitate FO instrumentation development and field deployment [ABSTRACT FROM AUTHOR]

Wind‐induced ground vibrations are a source of noise in seismic surveys. In a previous study, a wind‐ground coupling theory was developed to predict the power spectral density of ground motions caused by wind perturbations on the ground surface. The prediction was developed using a superposition of the point source response of an elastic isotropic homogeneous medium deforming quasi‐statically with the statistical description of the wind‐induced pressure fluctuations on the ground. Model predictions and field measurements were in agreement for the normal component of the displacement but underpredicted the horizontal component. In this paper, two generalizations are investigated to see if they lead to increased horizontal displacement predictions: (1) First, the dynamic point source response is calculated and incorporated into the ground displacement calculation. Measured ground responses are used to incorporate losses into the dynamic calculation. (2) The quasi‐static response function for three different types of nonuniform grounds are calculated and used in the seismic wind noise superposition. The dynamic point source response and the three more realistic ground models result in larger horizontal displacements for the point source at distances on the order of 1 m or greater from the source. However, the superposition to predict the seismic wind noise is dominated by the displacements very close to the point source where the prediction is unchanged. This research indicates that the modeling of the wind‐induced pressure source distribution must be improved to predict the observed equivalency of the vertical and horizontal displacements. Key Points: Two generalizations on a previous method for predicting ground vibrations caused by wind are investigatedA dynamic model for wind‐induced ground motion is developedThe wind‐induced surface deformations of three different types of nonuniform grounds are predicted [ABSTRACT FROM AUTHOR]