Topic Review
"Zorbas" on Southeastern Sicily
Over the last few years, several authors have presented contrasting models to describe the response of boulders to extreme waves, but the absence of direct observation of movements has hindered the evaluation of these models. The recent development of online video-sharing platforms in coastal settings has provided the opportunity to monitor the evolution of rocky coastlines during storm events. In September 2018, a surveillance camera of the Marine Protected Area of Plemmirio recorded the movement of several boulders along the coast of Maddalena Peninsula (Siracusa, Southeastern Sicily) during the landfall of the Mediterranean tropical-like cyclone (Medicane) Zorbas. Unmanned autonomous vehicle (UAV) photogrammetric and terrestrial laser scanner (TLS) surveys were performed to reconstruct immersive virtual scenarios to geometrically analyze the boulder displacements recorded in the video. Analyses highlighted that the displacements occurred when the boulders were submerged as a result of the impact of multiple small waves rather than due to a single large wave. Comparison between flow velocities obtained by videos and calculated through relationships showed a strong overestimation of the models, suggesting that values of flow density and lift coefficient used in literature are underestimated.
  • 764
  • 25 Aug 2021
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.
  • 58
  • 21 Oct 2022
Topic Review
Effect of Potassium on Tea Plant Growth
Potassium is among the three essential macronutrients for tea plants, along with nitrogen and phosphorous, and plays important roles in growth and stress response. Potassium is absorbed by plants in larger amounts than any other mineral element except nitrogen and, in some cases, calcium. Potassium is positively correlated with the elements nitrogen, copper, and zinc. Sufficient potassium dramatically improves the yield and quality of tea: it accelerates metabolism, promotes synthesis of catechins, and strengthens biotic and abiotic resistance by activating and regulating different enzymes. Moderate application of potassium fertilizers, along with potassium-solubilizing bacteria, can regulate the ratio of different forms of potassium and increase available potassium in soils of tea gardens.
  • 177
  • 06 Sep 2022
Topic Review
100,000-Year Problem
The 100,000-year problem ("100 ky problem", "100 ka problem") of the Milankovitch theory of orbital forcing refers to a discrepancy between the reconstructed geologic temperature record and the reconstructed amount of incoming solar radiation, or insolation over the past 800,000 years. Due to variations in the Earth's orbit, the amount of insolation varies with periods of around 21,000, 40,000, 100,000, and 400,000 years. Variations in the amount of incident solar energy drive changes in the climate of the Earth, and are recognised as a key factor in the timing of initiation and termination of glaciations. While there is a Milankovitch cycle in the range of 100,000 years, related to Earth's orbital eccentricity, its contribution to variation in insolation is much smaller than those of precession and obliquity. The 100,000-year-problem refers to the lack of an obvious explanation for the periodicity of ice ages at roughly 100,000 years for the past million years, but not before, when the dominant periodicity corresponded to 41,000 years. The unexplained transition between the two periodicity regimes is known as the Mid-Pleistocene Transition, dated to some 800,000 years ago. The related "400,000-year-problem" refers to the absence of a 400,000-year periodicity due to orbital eccentricity in the geological temperature record over the past 1.2 million years. The transition in periodicity from 41,000 years to 100,000 years can now be reproduced in numerical simulations that include a decreasing trend in carbon dioxide and glacially induced removal of regolith, as explained in more detail in the article Mid-Pleistocene Transition.
  • 35
  • 08 Oct 2022
Topic Review
17O in Hydrological Cycle
17O is the one of the naturally occurring stable isotopes of oxygen, and also it has the lowest abundance, 0.038%(). The distribution of isotopes in hydrological systems is controlled by isotope fractionation processes. Oxygen isotopes fractionate through mass-dependent isotopic fractionation, which includes kinetic processes, isotopic exchange reactions, and physicochemical phenomena (diffusion, condensation, and evaporation).
  • 340
  • 03 Aug 2021
Topic Review
1888 Ritter Island Tsunami
On the morning of March 13, 1888, an explosion took place on Ritter Island, a small volcanic island in the Bismarck and Solomon Seas, between New Britain and Umboi Island. This event is the largest volcanic island sector collapse in recent history. The explosion resulted in the almost complete loss of the island and generated a tsunami with runups of up to 20 meters (66 ft) that caused damage more than 600 kilometers (370 mi) away and killed anywhere between 500 and 3,000 on neighbouring islands, including scientists and explorers.
  • 19
  • 01 Nov 2022
Topic Review
1968 Burma Cyclone
The 1968 Burma cyclone was regarded as the worst to strike the country during the 20th century before it was surpassed by another unnamed cyclone in 2004 and further, Cyclone Nargis in 2008, respectively. The first tropical cyclone of the 1968 North Indian Ocean cyclone season, it started as a depression on May 7 on the northern Andaman Sea. With low wind shear and warm sea surface temperatures, the storm intensified in the waters near Burma before heading northwestwards. It then started to rapidly intensify, with an eye becoming apparent on satellite imagery on May 9. Also that day, it reached its peak intensity, with 3-minute maximum sustained winds of 220 km/h (140 mph) by the Indian Meteorological Department, which is equivalent to a super cyclonic storm; however, the agency treated the system as a severe cyclonic storm. Little to no changes happened on the cyclone as it turned northeastwards, making landfall near Akyab (now Sittwe) between 18:00 and 21:00 UTC on that day. Land interaction rapidly weakened the storm, dissipating on May 10 as an area of low-pressure in south Chin State. The predecessor to the cyclone caused light to moderate downpour to the Andaman Islands; however, no deaths were reported. Winds reported from the cyclone inland Burma reached an estimate of 60–100 mph, altogether with heavy rainfall and large storm surges. The former flooded the crops, submerging them in floodwaters in the process while the latter washed out villages near the path of the storm. Schools and hospitals throughout Akyab were destroyed by high winds and large waves, while the port suffered major damages. The town was almost destroyed due to the storm. In addition, some ships in the said harbor, including the Greek freighter Geros Michalos were reportedly sunk in the Bay of Bengal. Houses were destroyed during the storm and many livestock died, mainly due to drowning. The death toll from the cyclone was finalized on May 1968 at 1,307 individuals, while 2,000 more were reportedly missing. The property damages were estimated at K15 million kyat ($3.248 million United States dollar ). After the cyclone, the Government of Burma started to release aid to the victims, altogether with food supplies and cotton blankets. The Red Cross Society of the country donated cases of medicines to the country, while the United States Government released over 25,000 blankets to be transferred to the area. In addition, many countries and organizations including the UNICEF contributed over $121,291 (1968 USD) to Myanmar, following the disaster.
  • 13
  • 24 Nov 2022
Topic Review
2004 Indian Ocean Tsunami in Malaysia
The tsunami is one of the deadliest natural disasters, responsible for more than 260,000 deaths and billions in economic losses over the last two decades. The footage of the devastating power of the 2004 Indian Ocean tsunami perhaps remains vivid in the memory of most survivors, and Malaysia was one of the countries affected by the unprecedented 2004 tsunami. It was the first time the Malaysian government had managed such a great disaster. A compilation of post-event observations regarding tsunami characteristics is first presented in the form of maps, followed by building damage, including damage modes of wall failure, total collapse, debris impact and tilting of structures.
  • 1174
  • 25 Aug 2022
Topic Review
2017 in Paleomalacology
This list, 2017 in paleomalacology, is a list of new taxa of ammonites and other fossil cephalopods, as well as fossil gastropods, bivalves and other molluscs that are scheduled to be described during the year 2017, as well as other significant discoveries and events related to molluscan paleontology that are scheduled to occur in the year 2017.
  • 8
  • 27 Nov 2022
Topic Review
2020–2021 Taal Volcano Eruptions
Taal Volcano in Batangas, Philippines began to erupt on January 12, 2020, when a phreatomagmatic eruption from its main crater spewed ashes over Calabarzon, Metro Manila, and some parts of Central Luzon and Ilocos Region, resulting in the suspension of school classes, work schedules, and flights in the area. The Philippine Institute of Volcanology and Seismology (PHIVOLCS) subsequently issued an Alert Level 4, indicating "that a hazardous explosive eruption is possible within hours to days." Volcanic activity continued into 2021, when smaller eruptions occurred in July 2021.
  • 5
  • 24 Nov 2022
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