This study presents a forward model to quantify the P‐wave velocity (V_P), S‐wave velocity (V_S), and electrical conductivity (σ) of the solid‐liquid mixtures for a given set of pressure, temperature, lithology, liquid phase (aqueous fluid or melt), liquid fraction, and geometrical parameters in relation to the aspect ratio and connectivity of the liquid phase. This is based on previous experimental and theoretical studies on seismic velocity and electrical conductivity of solid rocks and liquid phases. A total of 78 lithologies, an aqueous fluid with NaCl (∼0–10 wt.%), and mafic to felsic melt appropriate for the crust and the uppermost mantle conditions were described in terms of V_P, V_S, and σ, as per previous experimental measurements and molecular dynamics simulation. This forward model is provided as a Windows executable program, and generates synthetic V_P, V_S, and σ, referring to the seismic velocities and electrical conductivity observed in the northeast Japan arc. After generation of the synthetic V_P, V_S, and σ, the original lithology and liquid parameters (phase, fraction, aspect ratio, and connectivity) were searched by implementing the grid search algorithm to map the misfit over the broad parameter space. The mapping shows the presence of a global misfit minimum around the optimized solution and the possibility of resolving the lithology and the liquid phase parameters based on the observed V_P, V_S, and σ by using the forward model presented in this study.

The Lamongan Volcanic Field (LVF), East Java, Indonesia, has experienced numerous maar eruptions, producing varied properties and morphologies of ash particles. This study conducted textural, morphometric, and geochemical analyses of the juvenile particles to elucidate the factors governing their heterogeneous characteristics. Two distinct types of juvenile ash were identified: A (black and brown ash) and B (orange-brown ash), reflecting different fragmentation processes. The blocky to slightly elongate shapes of juvenile A across heterogenous basaltic compositions (resulting in variable textures, rheological properties, and/or cooling histories) highlight the phreatomagmatic process as the primary control of their shape. In contrast, the irregular-fluidal shapes of juvenile B particles indicate magmatic fragmentation of basaltic andesite magma. This study reveals that variable magma properties yield diverse ash components, yet fragmentation dynamics govern pyroclast shapes in the LVF maar complex. Our integrated approach emphasizes the importance of considering multiple variables when interpreting heterogeneous volcanic ash deposits.

The presence of ophiolitic mélanges in the Indonesian archipelago has been acknowledged as pivotal for the paleo-tectonic reconstruction of the Southeast Asia Region (southwestern Sundaland). However, the occurrence of rodingite as an integral component of ophiolite in Indonesia has not been thoroughly documented. The rodingites within the Ciletuh Ophiolitic Mélanges in Western Java are notably fresh and widespread, providing a valuable opportunity to initiate comprehensive research on rodingites, particularly focusing on the interplay of metasomatism between serpentinite and meta-gabbro. These metasomatic processes can provide valuable insights into reconstructing the evolution of P-T conditions and elemental transfer involving fluids in a subduction zone. This study aims to focus on field occurrences, petrography, whole-rock geochemistry, with the application of P-T pseudosection modeling to describe their metamorphic conditions.Rodingitized gabbro in Ciletuh occur as dykes intersecting serpentinized peridotite with sharp and diffuse contact. These dykes are controlled by faults in direction opposite perpendicular or diagonal to the shearing direction of serpentinites. Sheared-foliated rodingite and serpentinite are common, usually forming boudinages. Rodingites are classified into six types which are: (1) Fine to medium grain clinopyroxene rich, (2) Fine to medium grain hydrogarnet rich, (3) Coarse grain, (4) Schistose, (5) Diffused serpentinite-rodingite at peripheral dyke, and (6) Diffused serpentinite-rodingite embedded within serpentinite. Type (1) to (3) are dykes which mostly composed by garnetized plagioclase (47-49%) and clinopyroxene (29-32%), orthopyroxene (20%), olivine (

The Genbudo lava, the late Pleistocene basaltic-andesitic lava flow in the southwestern part of Iwate Volcano, Japan, is a 70 m thick columnar jointed flow that can be divided into three parts from bottom to top: the colonnade, the entablature, and the partly-brecciated uppermost part. Two main types of fractures developed in the entablature: pseudopillow fractures that formed in a branching network-like pattern throughout the entablature, and sheet fractures with curved surfaces that are nearly parallel to each other. At the uppermost part of the flow, finger-like structures of lava extend upward from the coherent lava, and cogenetic autoclastic rocks form between the fingers. This occurrence suggests that hyaloclastites were generated during emplacement in the uppermost part of the flow, apparently when water from a dammed river valley covered the flow. The texture of the lava near the pseudopillow fractures in the entablature is commonly hypocrystalline, while the texture in other parts is holocrystalline. There are two types of pyroxene microlites, large prismatic (average size ~ 30 µm) and dendritic (< 10 µm in length) crystals in the lava near the pseudopillow fractures. These suggest that the cooling rate of the lava was greatest in the vicinity of the pseudopillow fractures. Networks of palagonite-filled micro-fractures (less than 10 µm in width) are found in this part of the flow, and many bubbles are observed along the fractures. This is clear evidence that the rapid cooling of the lava was caused by water infiltration through the pseudopillow fractures. From the measurement of Fe-rich droplet sizes that formed due to liquid immiscibility within the lava, we estimate the cooling rate within the colonnade as about 49 °C/h and within the entablature as 642 °C/h, consistent with much more rapid cooling by water infiltration from above.