Tag Archives: GPS

Which satellite is that? What does it measure?

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Space may well be the final frontier (there are one or two on earth that still require some work), but the space around our own planet is decidedly crowded. Folk at NASA’s Goddard Space Center (Maryland) estimate about 2300 satellites now orbit Earth; vehicles in various states of repair, use or disuse, of which a little more than 1400 are operational Continue reading

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The earth moved; GPS, earthquakes, and slow-slip

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A post about earthquake tremor swarms and slow slip events.

It is often useful to know where you are, in a spatial sense. In the old days (LOL), field geologists, the kind that make maps of rocks and earth structures would, armed with topography maps and compass, determine their location from some vantage point using line-of-sight and triangulation.  I don’t hanker for a return to these days. I’m grateful for the kind of location data instantly available on my smart phone – the little blue dot that seems to follow my course across some digital representation of the universe. But I acknowledge a kind of smugness, in the event the digital world nosedives, knowing that I can still find my way; no General Panic Stations (GPS) if the satellite-based Global Positioning System (the other GPS) fails.

GPS devices can also be attached to bits of the earth’s crust.  This is useful because the crust, whether continent, sea floor, or volcanic island, is always on the move. Continue reading

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