This week’s mosey around the geoscience world is more than a little serendipitous. There’s no theme, no connecting factor — just a bit of many of those things that make the subject so fascinating.
Earthquakes Large and Small
When I wrote the weekly earthquake digest, I always started with the largest event of the week. Just because I’ve stopped doing that specific style of digest doesn’t mean I’ll never write about another earthquake. This week, a tremor of M7.5 and its associated aftershocks — over 130 of them at the time of writing — caught my eye.
Large earthquakes in the western Pacific aren’t in themselves unusual, but they tend to be subduction-related and offshore. (I generalise.) This one, in Papua New Guinea, had the compressional nature of a subduction earthquake, but it occurred in the country’s Central Highlands.
Turning, as I so often do, to my favourite earthquake resource (Robert Yeats’s book on the planet’s active faults) I concluded that the earthquake is associated with the fold-thrust belt of the New Guinea Highlands. This is borne out by the USGS report on the earthquake which suggests that the cause was: “slip occurred on either a moderately dipping fault striking west-northwest, or on a moderately dipping fault striking southeast.”
This is a large earthquake, though not excessively so in its context. Some news reports are calling it the largest on record, but a quick search of the USGS archives indicates that it isn’t: the Central Highlands have seen five tremors of at least M7.0 in the past century, and many others of a similar magnitude have occurred in the country towards the subduction zone, the largest of them measuring M7.9.
And the Papua New Guinea earthquake was deadly as well as large. Though the population of the area isn’t high, there have been 20 deaths recorded at the time of writing and the number may rise. The American Geophysical Union’s blog was quick to pinpoint a further potential hazard, too — significant landslides generated by the ‘quake, which are not only blocking communication routes but also damming rivers — causing the potential for subsequent floods. As the blog notes: “This is an exceptionally dangerous situation that needs urgent attention.”
Lessons From Old Bones
It’s confession time. I’ve never quite understood the widespread appeal of dinosaurs, though I do like the odd fossil and I’m proud to be able to spell palaeontology without upsetting my spellcheck tool. But even I will sometimes raise my eyes from a bit of rock to look at an article on these creatures with interest. This week was one of those times.
Science News reported on the latest updates in the vexed question of ‘what is a dinosaur?’ You don’t know? Go and ask a ten year old child and see if they know. My guess is, they probably don’t, though they think they do. This article, which is essentially a summary of years of cumulative research, addresses exactly that question.
Biological classification (a biologist will surely correct me if I’m wrong) is based upon identification of shared characteristics, but with dinosaurs having existed for hundreds of millions of years and covering an enormous range of species, not to mention the small fact of their extinction, that’s always been problematic.
And as more dinosaurs are discovered, something that looks like a dinosaur may lack some of the signs that would previously identify a dinosaur — so the list of defining characteristics reduces. And now, apparently, we’re down to just one: “Today, only one fossil feature can be attributed solely to members of Dinosauria: a complete hole in the hip socket.”
So there you have it. Go and tell your ten year old.
To the Atacama Desert — and Beyond
Humans haven’t yet made it to Mars, and the unmanned missions that are there still have a lot to discover. But scientists, endlessly inventive as they are, aren’t stumped by this, looking to some of the most extreme environments on Earth to see if they can give any clues as to how life might adapt in the hostile surrounds of the Red Planet.
Mars has water, but not much — so the closest proxy is somewhere on Earth with water, but not much. That takes us to the driest desert on the planet, Chile’s Atacama. I can’t find rainfall figures (hardly surprising) but the received wisdom seems to be that parts of it can go for decades without rain — and a recent study has shown that when that rain comes, dormant microbial life responds.
Quite how accurate a proxy even this tough environment is for Mars remains to be seen, but it does demonstrate that life can persist in apparently lifeless environments as long as water is there, however occasionally. The study’s lead author, Dirk Schulze-Makuch, quoted on the Geology page website, noted that: “We believe these microbial communities can lay dormant for hundreds or even thousands of years in conditions very similar to what you would find on a planet like Mars and then come back to life when it rains.”
Volcano Cup Update
It’s nearly over. As I type, the closing rounds of the second semi-final pits Krakatua against Etna to see who’ll fight of with New Zealand’s Taupo volcanic field in the final.
I voted for Krakatua, as I have done throughout. There are many reasons for voting for may different volcanoes, but I can’t resist a fun fact, and Indonesia’s mighty mountain gives me one of my favourites.
According to no less a source than the Guinness Book of Records: “The loudest noise ever recorded was produced when the island-volcano Krakatoa exploded in an eruption … The sound was heard 5,000 km (3,100 miles) away.”