Sealed shear cracks associate abundant jog filled with albite, quartz, chlorite and calcite in the low - grade metamorphic rocks of the plate boundary. These shear crack jog should open at the time of shear crack growth and propagation, of which the shear slip velocity varies in the very wide range from km to nm order per second, suggesting that the volume increasing rate of the jog may become imbalance with the fluid influx from the surrounding matrix. The simulation of the fluid pressure in jog for various slip velocity can be carried out by means of the equation of state and inflow of aqueous fluid in the increasing jog volume controlled by the slip velocity. The results indicate the various patterns of rapid drop of fluid pressure depending on the shear slip velocity before jog collapse. The change in the degree of oversaturation of albite and quartz is inferred by the difference of fluid pressure in jog and matrix, because of saturation equilibrium of them with matrix aqueous fluid. Therefore, it is possible that the crystal shape of albite and quartz in jog is controlled by the degree of oversaturation controlled by the shear slip velocity, that means the speed of the shear crack slip motion. In the case of the fast earthquakes, the degree of oversaturation reaches over unity, and thus the crystal shape may be dendritic, but in the medium speed slip, it should be flower-like shape, and in the very slow slip event, it may be euhedral shape. The diagram of slip velocity and temperature is divided into the regimes of dendrite, flower, acicular (needle), and euhedral shape.

Short-lived fluid flow in the crust modifies hydrological properties and controls on the earthquake triggering. However, there are limited numerical constraints on the fluid volumes that can be rapidly transported. Comprehension of the timescales of fluid infiltration and the permeability evolution from geological samples is essential to estimating the fluid flux during crustal fracturing and its relation to seismic activities. This study focuses on fluid flow through a single fracture and scales its results to a series of low-magnitude fracturing events, such as tremors and low-frequency earthquakes, providing insights into fracturing and fluid-rock interactions in the lower–middle crust. Specifically, we analyse unique geological and geochemical evidence preserved in amphibolite-facies fluid-rock reaction zones to approximate the duration of fluid infiltration and time-integrated fluid fluxes and then determine the generated seismic moment and magnitude. This study is based on evidence of rapid fluid infiltration (~10 h) related to crustal fracturing and permeability evolution from low- to highly-permeable rocks (~10⁻⁹–10⁻⁸ m²). We estimate both through and perpendicular time-integrated fluid fluxes to a given fracture and the overall fluid-rock reaction zone. We present an advanced methodology for calculating the fluid volume via coupled reactive-transport modelling and thermodynamic analyses, focusing on Si alteration processes within reaction zones. In this study, we use two independent methods for constraining magnitude, which are based on fluid volumes and single fracture geometry. We compare the estimated values with the results provided by fluid injection experiments. Our finding reveals that the transportation of voluminous fluid volumes through a fracture (10¹ to 10⁴ m³) may be related to short seismic/aseismic events such as tremors and LFEs, as suggested from duration (~10 h) and cumulative magnitude, representing the maximum values as 2.0–3.8. In addition, we define the lower limit of the magnitude for a single fluid-driven seismic event as –0.6 to 0.2. However, a single fracture remains possible to transfer voluminous fluid flow and could be a key control on the generation of seismic activity above the tremor and slow slip events source regions in the lower–middle crust.

The geological correlation between the Korean Peninsula and China Cratons is important for the interpretation of the tectonic evolution of Northeast Asia. Jangbong Island is located in the northwestern coastal area of the Gyeonggi Massif on the Korean Peninsula. Combining with previous studies, this study interprets the tectonic evolution of the northern Gyeonggi Massif by analyzing the age of intrusion and metamorphism of the mafic igneous rocks in Jangbong Island. The basement of Jangbong Island consists of Paleoproterozoic gneiss and is covered by Neoproterozoic metasedimentary rocks. These rocks were intruded by mafic dikes that were metamorphosed into amphibolite. All rocks in Jangbong Island were intruded by Triassic gabbro and granite, and Jurassic granites. The U-Pb dating analysis on zircon analysis using LA-ICP-MS gives the intrusion ages of 917-873 Ma for amphibolites. The whole-rock geochemical analysis indicates that amphibolites are all alkaline and tholeiitic basalts formed in a within-plate tectonic setting. Two metamorphic ages of 254.4±2.8 Ma and 231.5±1.9 Ma were obtained from amphibolite with an intrusion age of 873 Ma. On the other hand, one metamorphic age was obtained for two amphibolites which give metamorphic ages of 255±12 Ma and 229.8±1.4 Ma, respectively. Zircons with metamorphic ages of 255-254 Ma have lower trace element contents and Th/U values than zircons with metamorphic ages of 231-229 Ma. During the Permo-Triassic continental collision between the North China Craton and South China Craton, Jangbong Island experienced intermediate-P/T peak metamorphism (680-630 °C/8.6-7.3 kbar) at ca. 255 Ma and then underwent low-P/T retrograde metamorphism (600-560 °C/5.7-3.1 kbar) at ca. 230 Ma. The Triassic gabbro gives an intrusion age of 229.1±0.57 Ma and formed in a post-collisional tectonic setting with Triassic granite. Together with previous data, this study supports the tectonic correlation between the northern Gyeonggi Massif and the North China Craton and the Permo-Triassic collision within the Gyeonggi Massif.