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Topic Review
“Every Earthquake a Precursor According to Scale” Model
The observation that major earthquakes are generally preceded by an increase in the seismicity rate on a timescale from months to decades was embedded in the “Every Earthquake a Precursor According to Scale” (EEPAS) model. EEPAS has since been successfully applied to regional real-world and synthetic earthquake catalogues to forecast future earthquake occurrence rates with time horizons up to a few decades. When combined with aftershock models, its forecasting performance is improved for short time horizons. As a result, EEPAS has been included as the medium-term component in public earthquake forecasts in New Zealand. EEPAS has been modified to advance its forecasting performance despite data limitations. One modification is to compensate for missing precursory earthquakes. Precursory earthquakes can be missing because of the time-lag between the end of a catalogue and the time at which a forecast applies or the limited lead time from the start of the catalogue to a target earthquake. An observed space-time trade-off in precursory seismicity, which affects the EEPAS scaling parameters for area and time, also can be used to improve forecasting performance. Systematic analysis of EEPAS performance on synthetic catalogues suggests that regional variations in EEPAS parameters can be explained by regional variations in the long-term earthquake rate.
  • 568
  • 21 Oct 2022
Topic Review
Carbon-Isotope Signature of Diagenetic Carbonates
Diagenetic carbonates often show large variations in their carbon isotope compositions. Variations are mainly the result of isotope fractionation effects during microbial metabolic processes, and these processes themselves may induce carbonate formation. Inorganic carbon from dissimilatory microbial activity shows negative carbon isotope values (d13C), in particular if methane is used as a carbon source. In turn, inorganic carbon produced during methanogenesis shows positive d13C values. The range of isotope values preserved in the carbonate phase ultimately depends on the reservoir sizes, diffusive mixing of different carbon sources, and episodic formation of carbonate. The carbon-isotope signature of diagenetic carbonates therefore represents an archive of past biogeochemical activity in the subsurface.
  • 1.7K
  • 30 Oct 2020
Topic Review
Characteristic Features of Skouries and Other Porphyry-Cu-Au+Pd±Pt Deposits
Many giant porphyry Cu-Au, Cu-Mo, and Mo-W deposits extend from the Pacific Rim to the Mediterranean and Carpathian system in Europe, the Himalayas, China, and Malaysia. However, only certain porphyry Cu-Au deposits, associated mostly with alkaline-type intrusions, are characterized by significant Pd and Pt contents, particularly in high-grade bornite–chalcopyrite and/or flotation concentrates. Such porphyry deposits include those in British Columbia, Colorado, in the Santo Tomas II deposit, the Philippines, the Skouries porphyry deposit, Greece, Elatsite, Bulgaria, the Kalmakyr deposit, Uzbekistan, the Grasberg deposit, Indonesia, Ok Tedi, Papua New Guinea, the Mamut deposit, Malaysia, and the Bajo de la Alumbrera, Argentina.
  • 78
  • 17 Nov 2023
Topic Review
Characterization of the Oxidation Products of Lipids
Phototrophic organisms (mainly green plants, algae, cyanobacteria and some protists) carry out photosynthesis that is, conversion of sunlight energy, carbon dioxide and water into organic materials. Due to the generation of highly reactive oxygen species (ROS) during photosynthetic electron transport, these organisms are particularly sensitive to oxidative damages. Lipids (hydrocarbons, pigments, terpenoids, free fatty acids, acylglycerides, phospholipids, galactolipids, cutins, suberins and waxes) are important components of phototrophic organisms, accounting for 16–26% of organic content in phytoplankton and up to 45% in the green alga Botryococcus Braunii.  The applications of gas chromatography-mass spectrometry techniques for the characterization of photooxidation and autoxidation products of unsaturated lipids of senescent phototrophic organisms will be introduced. 
  • 469
  • 21 Apr 2022
Topic Review
Coherence of Bangui Magnetic Anomaly
The interactions between the geophysical processes and geodynamics of the lithosphere play a crucial role in the geologic structure of the Earth’s crust. The Bangui magnetic anomaly is a notable feature in the lithospheric structure of the Central African Republic (CAR) resulting from a complex tectonic evolution.
  • 270
  • 12 May 2023
Topic Review
Cold-Water Coral Habitat Mapping
Cold-water coral (CWC) habitats are considered important centers of biodiversity in the deep sea, acting as spawning grounds and feeding area for many fish and invertebrates. 
  • 480
  • 25 Apr 2021
Topic Review
Diamond-Bearing Ophiolite
Ophiolites are fragments of ancient oceanic crust and upper mantle, which is created at ocean spreading ridges and then emplaced on land. Ophiolite-hosted diamond discovered in ophiolitic peridotite and chromitite is considered to be a new type that has been named an ophiolite-type by Yang et al., in 2011. 
  • 680
  • 22 Nov 2021
Topic Review
E-Region Auroral Ionosphere Model
E-region Auroral Ionosphere Model (AIM-E) is a numerical model involving both solar EUV radiation and electron precipitation as ionization sources. The AIM-E model allows to evaluate the concentration of the main ionospheric ions N+, N2+, NO+, O2+, O+(4S), O+(2D), O+(2P), electrons and  minor neutral components NO, N(4S), N(2D), for quiet and disturbed geomagnetic conditions at specified date, time and geographic location. The model design allows to  calculate the ionospheric composition in the entire high-latitude E-region in the retrospective, nowcast and forecast modes and shows good agreement with measurements.
  • 566
  • 02 Jul 2021
Topic Review
Earthquake Warning System Using Low-Cost Sensors in Taiwan
With advancements in technology and data processing speed, risk mitigation tools, such as earthquake early warnings (EEW), have emerged as life-saving guards in many earthquake-prone countries. The seconds-long warning achieved during EEW may be very helpful in saving the lives of human beings by allowing them to flee from buildings (if possible), or to take the proper shelter, or to move to a safer place within a building. 
  • 1.3K
  • 29 Nov 2021
Topic Review
Eudialyte-group minerals (EGMs)
       Eudialyte-group minerals (EGMs) are typical components of some kinds of agpaitic igneous rocks and related pegmatites and metasomatic assemblages. Crystal-chemical features of these minerals are important indicators reflecting conditions of their formation (pressure, temperature, fugacity of oxygen and volatile species, and activity of non-coherent elements.        A unique crystal-chemical diversity of EGMs is determined by a wide variability of their chemical composition involving more than 30 main elements and complex mechanisms of homovalent, heterovalent, and, especially, blocky isomorphism involving groups of atoms having different valency and coordination. The uniqueness of these minerals lies in the fact that they exhibit ability to blocky isomorphism at several sites of high-force-strength cations belonging to the framework and at numerous sites of extra-framework cations and anions.
  • 649
  • 26 Aug 2020
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