Earthquakes taking place “at different sides of the boundary” differ from each other not only by the depth. Shallow-focus earthquakes – they account for about 85% of all recorded events - often take place under the influence of periodic external effects, for example, rising tides, which disturb the entire lithosphere of the Earth. Periodicity is not inherent to deeper earthquakes, they always occur by chance. The conclusion was made by the researchers who had analyzed the world ISC/NEIC catalogues data that covers the 1964-2005 period and takes into account about 80,000 events.
Seismologists connect existence of the 70-kilometer boundary with water state changes in the interior of the Earth. The deeper the water molecules are located, the more compressed they are. At the depth of about 70 kilometers, the water compression strain index increases up to 1.3. This is the way water molecules are squeezed in the crystal lattice. Above this boundary, water exists mainly in free phase, below the boundary – water embeds into the rock crystallite composition.
The rock containing free water (above the boundary) promptly reacts to periodic tidal effects, even the faintest ones. Pressure changes and respective environment density changes cause formation of a crack system, where free water rushes to. The cracks widen, increase, and rock decay gives birth to a seismic focus. In the rock, where free water is absent (below the boundary), weak tidal effects are not accumulated and deformation does not grow.
So, the seismic boundary at the depth of about 70 kilometers (where, according to the researchers’ assumption, the lower hydrosphere boundary runs) separates the events that are able to react to external action and the ones incapable of such reaction. Therefore, this boundary separates different types of earthquakes. However, it is still a hypothesis that requires experimental validation.
Nadezda Markina | alfa
Sediment from Himalayas may have made 2004 Indian Ocean earthquake more severe
26.05.2017 | Oregon State University
Devils Hole: Ancient Traces of Climate History
24.05.2017 | Universität Innsbruck
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
26.05.2017 | Life Sciences
26.05.2017 | Life Sciences
26.05.2017 | Physics and Astronomy