Earth's Tectonic Plates Research Articles

Upaya Mengurangi Resiko Bencana di Pedesaan dengan Memanfaatkan Citra Penginderaan Jauh

The natural disaster is one of the phenomena that can occur at any time, anywhere and anytime. The most common disasters are floods, landslides, tornadoes and earthquakes, which can cause damage, loss of life and even loss of life. The conditions of Tabaroge Village and its surroundings are prone to flooding geographically, geologically, hydrologically and demographically. The condition of the East Luwu Regency area is at the confluence of several earth tectonic plates. Therefore, most of the potential disaster threats are in the Tabaroge Village area and its surroundings. Based on the occurrence of natural disasters in East Luwu Regency in recent years, which occurred in several villages. Judging from the characteristics of the Tabaroge Village area, Efforts to Reduce Disaster Risk in Rural Areas by Utilising Remote Sensing Imagery aims to provide information on locations that have disaster risk. This research uses the analysis methods of Standardised Precipitation Index (SPI), Normalised Difference Vegetation Index (NDVI), Normalised Difference Water Index (NDWI), Soil Adjusted Vegetation Index (SAVI) and Inverse Distance Weighted (IDW) for data exploration using Arcmap (GIS). In future development, it is expected to be able to implement disaster risk reduction by utilising remote sensing imagery in Tabaroge Village, East Luwu Regency.

VISUAL ANALYSIS OF LOCAL EARTHQUAKE IN NORTH TAPANULI BASED ON DATA SCIENCE

Earthquakes are natural phenomena that occur when the Earth's tectonic plates move and release energy. Big Data's emergent epistemological and research paradigms, as well as data science, an increasingly integrated field of data research, are opening up new opportunities. Visualizing earthquake data is all about understanding earthquake characteristics such as size, location and depth. The result show that September was the quietest month in terms of earthquakes, and in this graph we can see the number of earthquakes for each month in 2022. The month of October is the one that has the highest number of earthquakes. We can see the average depth and magnitude of each year on the bubble chart. In addition, the size and color of the bubbles indicate the number of earthquakes that month. In general, most of the earthquakes occurred in the shallow earthquake range and the 1.8-3.85 magnitude range.

Modes of Mantle Convection, Their Stability, and What Controls Their Existence

AbstractThe motion of Earth's tectonic plates is the surface expression of mantle convection beneath. Analytical convection models have attempted to relate observables, such as plate velocities and surface heat flow, with the thermo‐mechanical state of the mantle, and remain deeply influential in global geophysics. While such models tend to focus on describing the mantle's behavior today, there is evidence that suggests they may not be the best description for an earlier, hotter mantle. Early in Earth's history, higher temperatures may have led to different convective regimes that include active‐lid (today's form of convection), sluggish‐lid, and stagnant‐lid convection. In this study, we adopt and extend the analytical theory laid out by Crowley & O'Connell (2012, https://doi.org/10.1111/j.1365-246X.2011.05254.x) that self‐consistently characterizes the first two of these convection regimes. For a given thermo‐mechanical state, the theory predicts one to multiple solutions that each represent distinct modes of mantle convection. Here, we derive new scaling laws that connect these modes to the mantle's Rayleigh number and identify a new fundamental, dimensionless number, which we term the O’Connell number (named after Richard “Rick” J. O'Connell (1941–2015)), that describes a plate's resistance in context of the overall convection of the system. In addition, we identify two key bifurcations that bracket the Rayleigh‐O'Connell number space within which multiple solutions may exist. Finally, we remove the assumption of steady‐state in their original framework in order to perform a linear stability analysis to characterize the relative stability of each convection mode.

The Impact of Plate Motions on Long‐Wavelength InSAR‐Derived Velocity Fields

AbstractInterferometric Synthetic Aperture Radar (InSAR) measurements are increasingly being used to measure small amplitude tectonic deformations over large spatial scales. Residual signals are often present at these scales and are interpreted to be noise of indeterminate origin, limiting studies of long‐wavelength deformation. Here, we demonstrate the impact of rigid motion by the Earth's tectonic plates on velocity fields derived from InSAR. The range‐dependent incidence angle of the InSAR observations, coupled with plate velocities of centimeters per year, can induce long‐wavelength spatial gradients of millimeters per year over hundreds of kilometers in InSAR velocity fields. We show that, after applying corrections, including for the ionosphere and troposphere, plate motion represents the dominant source of long‐wavelength secular velocity gradients in multi‐year time series for several study areas. This signal can be accounted for using plate motion models, allowing improved detection of regional tectonic strain at continental scales.

Natural observations of subduction initiation: Implications for the geodynamic evolution of the Paleo-Asian Ocean

Initiation of new subduction zones is an integral part of Earth's plate tectonics regime. It is generally accepted that the negative buoyancy of sufficiently old oceanic lithosphere provides the primary driving force for subduction initiation. However, the dynamic processes of the subduction initiation are still debated. In this paper, we summarize representative geological records of subduction initiation, including supra-subduction zone (SSZ) ophiolitic mélanges, forearc basalts and metamorphic soles, and review four typical mechanisms of the subduction initiation using natural examples from circum-Pacific and Tethyan subduction zones, including Izu-Bonin-Mariana (IBM), Oman, Caribbean and Solomon examples for subduction initiation by transform fault collapse, mid-ocean ridge inversion, plume-induced, and polarity reversal, respectively. Above three rock records were also preserved in different stages of evolution of the Central Asian Orogenic Belt (CAOB), which is one of the largest and long-lived accretionary orogenic belts on Earth, and indicated that the subduction initiation began at 1.02 Ga in the northern Paleo-Asian Ocean (PAO), but started at the Early Cambrian in the southern PAO. The plume-induced subduction initiation might play the dominant role prior to Cambrian, and other models were also operated in the evolution of the CAOB. More importantly, this study highlights a crucial link between SSZ ophiolitic mélanges associated with metamorphic rocks and subduction initiation in the CAOB. Therefore, we recommend that future research in this direction focuses on the SSZ ophiolitic mélanges, forearc basalts and metamorphic soles in the CAOB, this will open the door for geologists to contribute fundamentally to understanding subduction initiation in the PAO.

Plato’s cube and the natural geometry of fragmentation

Plato envisioned Earth's building blocks as cubes, a shape rarely found in nature. The solar system is littered, however, with distorted polyhedra-shards of rock and ice produced by ubiquitous fragmentation. We apply the theory of convex mosaics to show that the average geometry of natural two-dimensional (2D) fragments, from mud cracks to Earth's tectonic plates, has two attractors: "Platonic" quadrangles and "Voronoi" hexagons. In three dimensions (3D), the Platonic attractor is dominant: Remarkably, the average shape of natural rock fragments is cuboid. When viewed through the lens of convex mosaics, natural fragments are indeed geometric shadows of Plato's forms. Simulations show that generic binary breakup drives all mosaics toward the Platonic attractor, explaining the ubiquity of cuboid averages. Deviations from binary fracture produce more exotic patterns that are genetically linked to the formative stress field. We compute the universal pattern generator establishing this link, for 2D and 3D fragmentation.

The Influence of Water on the Strength of Olivine Dislocation Slip Systems

AbstractThe nature of lattice‐preferred orientation (LPO) in olivine‐rich rocks strongly influences many important physical properties of Earth's upper mantle. Different LPO types have been observed to develop in deformation experiments on olivine‐rich rocks carried out at different water fugacity conditions. The development of the different LPO types has been attributed to dislocation slip systems in olivine having different sensitivities to water fugacity, but this hypothesis has not been directly tested. To measure the influence of water fugacity on the relative strengths of olivine dislocation slip systems, we carried out a series of deformation experiments on olivine single crystals under either anhydrous or hydrous conditions. The crystals were oriented to activate either the (010)[100], (001)[100], or (100)[001] dislocation slip systems using a direct shear geometry, which allows for isolation of single slip systems, in contrast to the multiple systems activated in experiments carried out in compression. Post‐deformation electron backscatter diffraction analyses reveal orientation gradients consistent with deformation occurring via the motion of dislocations on the activated slip systems. Crystals in all of the investigated orientations exhibit hydrolytic weakening, but crystals oriented to activate the (001)[100] slip system exhibit the largest degree of weakening. These results are consistent with a water‐induced change in LPO in olivine‐rich rocks deforming by dislocation creep. The rheological data obtained from the experiments can be used to improve models of LPO evolution in Earth's mantle, which is critical for imaging the structure of Earth's interior and predicting the movement of Earth's tectonic plates.

Proposed landing on europa: instruments, radiation shielding, planetary protection, and mission

Europa is a moon of the planet Jupiter. Slightly smaller than Earth's own moon, it is the smallest of the four Galilean moons of Jupiter but the sixth largest moon in our solar system. Its primary feature is its highly reflective surface; preliminary indications are that it may have a massive ocean underneath its icy crust. In 2013, the Hubble Space Telescope detected indications of water-vapor plumes [1]. Furthermore, Europa's variegated shell may be the result of geological activity, like Earth's plate tectonics. In 2015, NASA reported that sea salt may coat some surface features on Europa [2]. Outside of Earth, Europa is the most promising body in the solar system for supporting life. Europa might support a base for human habitation while performing interplanetary exploration.

Global drainage patterns and the origins of topographic relief on Earth, Mars, and Titan.

Rivers have eroded the topography of Mars, Titan, and Earth, creating diverse landscapes. However, the dominant processes that generated topography on Titan (and to some extent on early Mars) are not well known. We analyzed drainage patterns on all three bodies and found that large drainages, which record interactions between deformation and erosional modification, conform much better to long-wavelength topography on Titan and Mars than on Earth. We use a numerical landscape evolution model to demonstrate that short-wavelength deformation causes drainage directions to diverge from long-wavelength topography, as observed on Earth. We attribute the observed differences to ancient long-wavelength topography on Mars, recent or ongoing generation of long-wavelength relief on Titan, and the creation of short-wavelength relief by plate tectonics on Earth.

River systems reveal planetary tectonics

Planetary Topography![Figure][1] An ancient river erodes the landscape in Namibia. PHOTO: ERIC NATHAN/ALAMY STOCK PHOTO Earth, Mars, and Titan have all hosted rivers at some point in their histories. Rivers erode the landscape, leaving behind signatures that depend on whether the surface topography was in place before, during, or after the period of liquid flow. Black et al. developed two metrics to measure how well river channels align with the surrounding large-scale topography (see the Perspective by Burr). Earth's plate tectonics introduce features such as mountain ranges that cause rivers to divert, processes that clearly differ from those found on Mars and Titan. Science , this issue p. [727][2]; see also p. [708][3] [1]: pending:yes [2]: /lookup/doi/10.1126/science.aag0171 [3]: /lookup/doi/10.1126/science.aan2719

Creeping faults: Good news, bad news?

AbstractThe motion of the Earth's tectonic plates drive fault slip. Some faults slip in sudden movements, releasing great amounts of energy during large earthquake ruptures, while others slip in steadier movements which release energy more slowly. The latter, known as creeping faults, are believed to be less hazardous but there is mounting evidence that they are more complex than previously thought and can also pose a significant hazard. A recent review by Harris [2017] documents the earthquake potential of creeping faults in shallow continental fault zones from worldwide data. She presents a comprehensive review of prior studies; key insights into when, where, and why fault creep takes place and under which conditions creeping faults may represent high seismic hazard and suggests some directions for future research.

Alignment between seafloor spreading directions and absolute plate motions through time

AbstractThe history of seafloor spreading in the ocean basins provides a detailed record of relative motions between Earth's tectonic plates since Pangea breakup. Determining how tectonic plates have moved relative to the Earth's deep interior is more challenging. Recent studies of contemporary plate motions have demonstrated links between relative plate motion and absolute plate motion (APM), and with seismic anisotropy in the upper mantle. Here we explore the link between spreading directions and APM since the Early Cretaceous. We find a significant alignment between APM and spreading directions at mid‐ocean ridges; however, the degree of alignment is influenced by geodynamic setting, and is strongest for mid‐Atlantic spreading ridges between plates that are not directly influenced by time‐varying slab pull. In the Pacific, significant mismatches between spreading and APM direction may relate to a major plate‐mantle reorganization. We conclude that spreading fabric can be used to improve models of APM.

Lithospheric controls on magma composition along Earth's longest continental hotspot track.

Hotspots are anomalous regions of volcanism at Earth's surface that show no obvious association with tectonic plate boundaries. Classic examples include the Hawaiian-Emperor chain and the Yellowstone-Snake River Plain province. The majority are believed to form as Earth's tectonic plates move over long-lived mantle plumes: buoyant upwellings that bring hot material from Earth's deep mantle to its surface. It has long been recognized that lithospheric thickness limits the rise height of plumes and, thereby, their minimum melting pressure. It should, therefore, have a controlling influence on the geochemistry of plume-related magmas, although unambiguous evidence of this has, so far, been lacking. Here we integrate observational constraints from surface geology, geochronology, plate-motion reconstructions, geochemistry and seismology to ascertain plume melting depths beneath Earth's longest continental hotspot track, a 2,000-kilometre-long track in eastern Australia that displays a record of volcanic activity between 33 and 9 million years ago, which we call the Cosgrove track. Our analyses highlight a strong correlation between lithospheric thickness and magma composition along this track, with: (1) standard basaltic compositions in regions where lithospheric thickness is less than 110 kilometres; (2) volcanic gaps in regions where lithospheric thickness exceeds 150 kilometres; and (3) low-volume, leucitite-bearing volcanism in regions of intermediate lithospheric thickness. Trace-element concentrations from samples along this track support the notion that these compositional variations result from different degrees of partial melting, which is controlled by the thickness of overlying lithosphere. Our results place the first observational constraints on the sub-continental melting depth of mantle plumes and provide direct evidence that lithospheric thickness has a dominant influence on the volume and chemical composition of plume-derived magmas.

In-situ stress measurements and regional stress field assessment in the Xinjiang candidate area for China's HLW disposal

Altogether 180 hydraulic fracturing (HF) in-situ stress measurements were conducted in a pre-selected area in the Xinjiang Uygur Autonomous Region, China, which is being considered as one of the candidate areas for China's high-level radioactive waste (HLW) repository. In-situ stress magnitudes and orientations in three sub-areas (i.e., Yamansu, Tianhu and Aqishan sub-areas) were obtained from 163 valid measurement points in eight sub-vertical boreholes at depths ranging from 17 to 647m, and the variation of the in-situ stress components with depth was analyzed. The measurement results show that the maximum horizontal stress is larger than the vertical stress within most of the measurement depth ranges, indicating that the regional stress field is dominated by tectonic horizontal stress rather than by the overburden stress (σv). Within the range of the tested depths, the stress field is characterized by σH>σv>σh, where σH and σh are the maximum and minimum horizontal stresses, respectively. Fracture impression results reveal that the maximum horizontal stress is dominantly oriented in the NEE–SWW direction, which is in general in agreement with the orientation of regional tectonic stress field generated from movement of the Earth's tectonic plates and is consistent with those interpreted by GPS measurements and focal mechanism solutions. In addition, an abnormal phenomenon in performing stress measurements in one borehole was noticed and the result was discussed using borehole injection test data.

Earth's tectonic plates skitter about

Earth's tectonic plates skitter about

What drives Earth's thermodynamic engine?

Geology The asthenosphere lies right below Earth's tectonic plates. The asthenosphere is a thin layer of partially molten rock that has long been thought to play a minor role in Earth's thermodynamic engine. In a Perspective, Anderson and King highlight recent studies that point to a much more active role for the asthenosphere. They argue that this layer is hotter than the mantle below. It may thus be a source of hotspot volcanoes that have been widely attributed to plumes rising up from the lower mantle. Furthermore, model studies suggest that the asthenosphere has a strong effect on patterns of mantle flow. Science , this issue p. [1184][1] [1]: /lookup/doi/10.1126/science.1261831

Earth's plate tectonics speeding up, says study

Earth's plate tectonics speeding up, says study

Drilling to Resolve the Evolution of the Corinth Rift

The initiation and evolution of continental rifting, ultimately leading to rifted margin and ocean basin formation, are major unanswered questions in solid Earth–plate tectonics. Many previous insights have come from mature rifted margins where activity has ceased or from computer models. The Gulf of Corinth Rift in central Greece presents an ideal laboratory for the study of young, highly active rifting that complements other rift zones (e.g., the East African and Gulf of California rifts). Exposure and preservation of syn‐rift stratigraphy, high rates of extension, and an existing network of offshore seismic data offer a unique opportunity to constrain the rift history and basin development at exceptionally high resolution in the Gulf of Corinth.

New origin seen for Earth's tectonic plates

New origin seen for Earth's tectonic plates

Reconstructing Plate Tectonics

Geophysics The modern-day distribution of Earth's tectonic plates is just a snapshot of an ever-changing process. Reconstructions of previous plate arrangements have resulted in the identification of the ancient supercontinents Pangea and Rodinia, but does this cycle follow any sort of predictable law o r pattern? Morra et al. statistically analyzed the organization of large and small plates across Earth's surface over the past 200 million years, based on models of plate reconstructions. Small plates do not show much statistical variation in their distribution over time, because they are largely unstable and form from unrelated events. Large plates, however, tend to organize either into heterogeneous or homogenous states based on plate size distributions over ∼100-million-year time scales. The rapid rate at which heterogeneous distribution states are stabilized suggests that these may be excited states, whereas homogeneous distribution states tend more toward equilibrium. In this case, the underlying driving force for the transition from one state to another depends on cycling between top-down and bottom-up mantle convection as a control on plate motion. Earth Planet. Sci. Lett. 373 , 93 (2013).