Answer:
Some, but not all, earthquakes are related to volcanoes. ... However, most earthquakes are caused by the interaction of the plates not the movement of magma . Most earthquakes directly beneath a volcano are caused by the movement of magma. The magma exerts pressure on the rocks until it cracks the rock.
"The Silurian is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at 443.8 million years ago, to the beginning of the Devonian Period, 419.2 Mya.<span> <span>Wikipedia."
https://www.google.com/search?q=He+Silurian+period+occurred&rlz=1C1RUCY_enUS760US760&oq=He+Silurian+...
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Answer: It is the result of a mixture of radiation from many independent sources, such as stars and galaxies.
Microwave background radiation is a form of electromagnetic radiation that is present in the whole universe and completely fills it. In fact, it is the leftover radiation from the Big Bang that occurred 400,000 years before the events related to this cosmic radiation.
Its frequency belongs to the microwaves range and is one of the main demonstrations of the of the Big Bang theory model.
