Why We Still Can’t Predict Earthquakes – and We Probably Never Will
Every few years or so, the world has to deal with one catastrophic earthquake, which, especially when it hits somewhere in the developing world, can result in massive loss of life and property. The most recent one was in Nepal, where the latest death has exceeded 5,000. What makes these earthquakes even more terrifying is the fact, even though we understand them pretty well and our data gathering and computational capabilities have increased a lot over the years, scientist still have basically no way of knowing exactly when the next big one will occur. So what makes earthquakes so difficult to predict?
First of all, we have to understand what causes an earthquake. Our planet’s crust, the relatively thin outermost layer of our planet which floats on top of the semi-molten mantle, is divided into several huge slabs of rock called tectonic plates, like the cracked shell of a boiled egg. These plates aren’t static – powerful currents within the mantle slowly move them around, at a rate of a few millimeters or centimeters per year. Huge tensions build up in the places where they meet (called plate boundaries) because as the plates move, the boundaries themselves stick, due to friction. Eventually, the rocks snap (or slip), and all that tension is released as seismic waves – this is what’s called the stick-slip process, and it’s what causes earthquakes.
Over the years, as our understanding of this phenomenon got better, we’ve been getting better at forecasting (not predicting!) earthquakes. It all started with recognizing that earthquakes are caused by faulting, the movement of rock along a break in the surface (a fault), and not, as previously thought, the other way around – the cracks in the earth were just a result of the earthquake. Today we know that most seismic events happen where tectonic plates collide head-on or slide along one another, which tells us where to expect them and where we should better prepare.
There are other things seismologists can do to try to actually determine when the next big one will happen. They can use historical and geological records to determine the intensity and frequency of past earthquakes. Also, they can improve the current models of what happens along the plates and roughly estimate the time and place where a big earthquake might occur. Once again, we’re talking about a forecast – scientists are basically saying an earthquake will occur sometime in the next couple of decades. And it’s highly unlikely they’ll ever be able to do better.
That’s because those earthquake-generating tectonic plates are huge, 100 km thick on average, and tremendously heavy. In order to predict when an earthquake will happen, you’d have to know precisely the weight, speed, and direction in which these massive slabs of rock are moving; you’d have to understand the underlying mechanism which makes them move; and you’d have to exactly what kind of rocks are they made of and what are their properties, so you know how much force is needed to break them. Also, keep in mind earthquakes happen dozens or hundreds of kilometers below the surface, so you’d need to gather all this data from extremely deep underground. It’s highly unlikely we’ll ever be able to do all of this.
While we can’t predict earthquakes in time to actually organize an evacuation or take other measures which require adequate advance warning, we could do other things to mitigate the damage. First of all, there are a number of simple things each and every one of us can do to make sure we are prepared in case of a disaster. Things like securing furniture or knowing where to take cover when the ground starts to shake (here’s a link with some of these tips, or watch the video below).
But perhaps the best thing we could do in order to reduce damage from seismic events would be to build earthquake-proof structures. Engineers in Japan and California have come up with intriguing ideas to reinforce buildings, making them better suited to withstand a powerful shock. And there are plenty of low-tech ways to improve houses in the developing world as well.
Probably the only thing we can tell for sure about future big earthquake is that we’ll never be able to tell exactly when it will hit. Nevertheless, seismologists do know where earthquakes are most likely to occur, and could maybe even set a time frame for the event. Knowing which places are at risk is a valuable piece of information in and of itself, and could be used to put in place various measures, thus greatly limiting the damage done by these natural disasters.
New Evidence Modifies Homo sapiens Chronology and Behavior
Earlier this month, researchers published an article outlining new evidence from an excavation in Jebel Irhoud (Morocco) that provides the earliest date yet for the presence of Homo sapiens. A variety of dating methods provide an age of about 315,000 years ago (kya). Prior to this, the earliest securely dated evidence for Homo sapiens were the bones from the Omo Kibish site in Ethiopia dating to about 195 kya.
The decades-long excavation at Jebel Irhoud has uncovered various types of palaeo archaeological data. The skeletal material (e.g. skull, mandible, teeth, humerus, hip bone) shows that there were at least five individuals. The assemblage of stone tools includes examples of the Mousterian industry and the Levallois napping technique. Both of these are closely associated with Neanderthals (Homo neanderthalensis), though are not exclusive to the species. Also, the majority of the tools were made from stone not native to the Jebed Irhoud area. Other recovered evidence includes examples of fire use and animal bones (primarily gazelle) showing signs of hunting and butchering.
A variety of dating techniques helped establish the age of the new assemblage at 315 kya. The research team measured sediment from the different stratigraphic levels for the quantity of radiation present. They used electron spin resonance on bone samples. Finally, the researchers applied thermoluminescence to the stone tools that were in direct association with the bones. Unfortunately, the research team was unable to extract DNA from the bones.
Importance of Evidence
The importance of the evidence is twofold. First, it secures a mature development of Homo sapiens over 100,000 years earlier than previous evidence indicated. The date does not remove the firm placement of Homo sapiens within the Middle Pleistocene and during the Middle Palaeolithic. However, a date of 315 kya does provide overlap with the existence of Homo heidelbergensis. Previous evidence indicated that Homo sapiens developed from Homo heidelbergensis between 300 – 200 kya. The Jebel Irhoud data do not exclude this hypothesis but it means that Homo sapiens must have developed much earlier, probably closer to the nadir of Homo antecessor. It also means that Homo sapiens had much longer contemporaneity with Homo erectus than previously known.
The second important aspect is the location of the finds. Morocco is around 3,400 miles from Ethiopia. The prevailing models of human evolution place the development of Homo sapiens in Ethiopia. This makes sense based on the quantity and age of data recovered from sites in Ethiopia and in East Africa. The location of the new finds, and the fact that the fossils represent developed Homo sapiens, indicate that our ancestors had already moved across the continent in viable population sizes so the broad evolutionary changes that resulted in our species had already occurred.
The Jebel Irhoud evidence does not lessen the importance of East Africa in understanding the development of our species. Rather, it contributes data to provide a richer, more robust picture of hominid development and migrations across Africa and the world. It is quite exciting to imagine what else the excavation will recover to further elucidate the history of hominids and Homo sapiens. What are your thoughts?
Volcanic rocks’ primordial water suggests life might be more common
Life on other planets is considered to be a certainty, and with new evidence of the infinitely intricate details of the universe and their influence on Earth come to light more often as ever, it is undoubtable. However, in a new study involving volcanic rocks and the types of isotopes they contain revealed that life could be more common in the universe than we might have expected.
Volcanic rocks examined by Lydia Hallis and her planetary scientist colleagues revealed that the Earth might have been “born with water”. In the theory they put forward in the latest issue of Science magazine, they argue that the isotopes discovered within volcanic rocks found in Iceland and Baffin Island suggest water had been part of Earth since it first started forming within the protosolar nebula.
Based on the light hydrogen isotope ratio discovered in the volcanic rocks we mentioned earlier, the primordial water within trapped within the rocks came from the protosolar nebula. The researchers demonstrated in their paper last week that the hydrogen isotope ratio in the volcanic rocks was much lighter than ocean water, making it much older. The discovery could hold against the theory that the water on our planet came from numerous water-contaminated asteroid collisions.
The breakthrough came after scientists evaporated volcanic rocks and examined the trapped water in their insides, revealing that Earth has not in fact gathered its water isotopes over the years due to debris from outer space impacting its surface, as previous theories believed. In fact, the primordial water from within the volcanic rocks of Iceland might be straight out of the Protosolar Nebula – or the gas and hydrogen molecular clouds that eventually became the Solar System.
The theory suggests that if the Solar System’s nebular history of formation is considered, then we should be able to find many different solar systems with planets like Earth orbiting around. These planets could have actually harbored the same primordial water at one point in time in the past few billion years, and if their geology was as fortunate as Earth’s, they might have evolved in the same way our own planet has. Water may signify the presence of biological life, thus the chances of finding planets similar to Earth might be slightly higher. The theory cannot be considered definite proof, of course, but it does propose an interesting idea.
If planets within solar systems are formed from the same materials as the primordial protosolar nebula, and are capable of retaining water in a similar manner to Earth, the possibility of finding life closer to home is greatly increased. However, that doesn’t mean that we might be closer to intelligence. You might have heard theories about inferior forms of life being closer to us than we had ever thought – on Mars, for instance. In the future, we might discover primordial water on the Red Planet.
The volcanic rocks that the scientists base their theory on can now be considered as the first evidence of primordial water on Earth. If you want to get in on the science behind analyzing these unique volcanic rocks, you can read the full study in Science magazine. The discovery is significant and brings us one step closer to identifying the first planet, aside from Earth, harboring biological life.
Unusual double crater found in Sweden
Erik Sturkell, Professor of Geophysics at the University of Gothenburg, led a team of researchers who discovered two craters in the Swedish country of Jämtland. One huge crater, with a diameter of 4.6 miles was found south of Östersund in Brunsflo and another smaller crater, with a diameter of 0.4 miles was located 9.9 miles. What’s unique about the craters is that they are both made by meteorite impacts 458 million years ago and the impacts happened at the same time. No other meteorite impacts around the world have been dated at the same exact time.
“Information from drilling operations demonstrates that identical sequences are present in the two craters, and the sediment above the impact sequences is of the same age. In other words, these are simultaneous impacts,” says Erik Sturkell. Several others meteorites have been found all around Sweden. An interesting fact is that large meteors explode and disintegrate at impact, leaving behind enormous craters, while small meteorites fall as stones. A lot of these types of stone, which are actually meteorites, were found all around Sweden in 1940.
“Around 470 million years ago, two large asteroids collided in the asteroid belt between Mars and Jupiter, and many fragments were thrown off in new orbits. Many of these crashed on Earth, such as these two in Jämtland,” explained Erik Sturkell, by that time, Jämtland, was under the sea. It seems that 460 million years ago was a very dangerous place to live on earth, because of the numerous meteorite impacts. Makes you wonder when a big meteorite will hit earth again.
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