The surface of our planet varies greatly in altitude. In fact about ¾ are covered by seawater, whose average level has been conventionally chosen as a reference for the surface elevations. The statistical analysis of the elevations of the earth’s surface shows us something interesting: the highest percentage of the elevations is around two particular values that are the average level of the ocean floor (about -3790) and the average level of the emerged lands (about 840 m).
On the relative graph of the percentage distribution of the areas with respect to the altitudes, called “hypsographic curve”, it can be noted that the portions of surface that reach the minimum altitudes (about -11000 m of the Mariana Trench) and the maximum ones (8850 m of Mount Everest) are a very small fraction of the total.
In a nutshell, the mountain ranges are almost an exception, as are the oceanic trenches, on the surface of the Earth. They appear in so-called belts, which are considerably more developed in one direction than in the other. But what is it that keeps them standing at such exceptional altitudes compared to most of the land above ground?
A bit of a big headline. I’ll explain the earthquakes. Who do I think I am? Well… I’m a geologist. I know the problem. If you want to know about heart attacks, you ask a cardiologist, right? If you lose your tap, you call the plumber, not the cardiologist. Or am I wrong? Geologists know about earthquakes. They have to. It’s a must. Even if they’re not going to deal with earthquakes in their career, they must be familiar with the phenomenon. So, by academic background geologists know very well that earthquakes are an entirely natural phenomenon over which man has no influence. It is due to the fact that the Earth’s lithosphere (the most superficial rocky envelope of the planet) is divided into a series of plates and microplates; most of the earthquakes are distributed along their margins because the plates move one with respect to the other. And huge blocks of rock “rubbing” each other make a big mess. The “mess” are earthquakes: rock breaks, and the energy released at the moment of breaking propagates in all directions in the form of seismic waves, oscillations of the rocky body that also involve the surface on which we live. They are waves completely similar to those generated by a rock thrown into the water (but they are not only those – it’s just to give an idea).
Fifty years after Apollo 11 astronauts deployed the first seismometer on the surface of the Moon, NASA InSight’s seismic experiment transmits data giving researchers the opportunity to compare marsquakes to moon and earthquakes.
Seismologists operating the Marsquake Service at ETH Zurich literally rocked and rolled as they experienced, for the first time, two “marsquakes” in the university’s quake simulator. Researchers uploaded actual data from marsquakes detected on Martian solar day or Sol 128 and 173.The marsquakes were detected by the SEIS seismometer, whose highly sensitive electronics were delivered by the Aerospace Electronics and Instruments laboratory at ETH.
Fifty years ago, when astronauts first landed on the moon, they carried not only humanity’s highest hopes but an important experiment from Columbia.
On the afternoon of July 20, 1969, Gary Latham ’65GSAS, a thirty-three-year-old geophysicist at Columbia’s Lamont-Doherty Geological Observatory, arrived at NASA’s Manned Spaceflight Center (now the Johnson Space Center) in Houston to witness the fulfillment of thousands of years of curiosity and wonder: humanity’s first attempt to land men on the moon…
Many are aware that dinosaurs disappeared nearly 66 million years ago, after a major climate change that made their environments inhospitable. Most people know about the dinosaurs disappearance, but few know that what happened at the end of the Mesozoic era was actually a mass extinction. Well, maybe even fewer people know that some clues of what happened in that period have been first found in central Italy, close to Saint Francis’ hometown, near a small city in the Apennines called Gubbio. The story is about father and son, Louis Alvarez, a Nobel prize physicist, and Walter Alvarez, a renown American geologist at Berkeley with a love for Italy.