Highly Allochthonous | NEWS & COMMENTARY FROM THE WORLD OF GEOLOGY & EARTH SCIENCE

317 years since the last rupture of the Cascadia megathrust

Posted on January 26, 2017 by Chris Rowan

At around 9pm on the 26th January 1700, the Cascadia subduction zone – a shallowly dipping thrust fault that runs more than 1000 km north from Cape Mendocino in Northern California to the vicinity of Vancouver Island, ruptured in an estimated magnitude 9 earthquake. No Europeans were there to witness the shaking and the inundation that followed, as the Oregon and Washington coasts were engulfed by tsunami more than 10 m high. But indigenous people were, and some of their oral accounts, of this earthquake and similar ones before it, still survive. The tsunami crossed the Pacific basin to Japan, where it was recorded as an ‘orphan’ tsunami (one that was not preceded by a large local earthquake). The Japanese records are how we precisely know the day and rough time of the rupture.

More recent records from Japan – pictures and video of the tsunami generated by the 2011 Tohoku earthquake – provide a sobering vision of what the Cascadia megathrust might do to the Pacific Northwest when it next wakes up. 317 years have passed, and we can’t know precisely how many more might pass before the next big earthquake. Records of giant submarine landslides triggered by large subduction zone ruptures, preserved in sediments off the Cascadia margin, show that on average, a big rupture like the 1700 event occurs every 500 years or so. But the Earth is not clockwork, and the gap between two individual earthquakes can vary significantly from the long-term average. All we know is that it will happen at some point in the next few hundred years, and we had best get prepared.

This is not exactly happy knowledge. Nonetheless, having that knowledge is still something to be thankful for, when we consider the all-too-common alternative: us going about our rapid human business, unaware that the slow geological workings of the planet beneath our feet are turning, building up to a disaster we never see coming until it is upon us. But for Cascadia, dogged and careful scientific detective work* over the past thirty years means that we are in the relatively happy position of comprehending the threat before it takes us by unpleasant surprise.

It could still be a tragedy – even the most recent assessments make it clear that there is still plenty of work to do to prepare the region for the day when the ‘years since last rupture’ counter flips back to zero. But knowledge is power, and in this case it is life-saving power.

*much of it, I feel compelled to point out in these interesting times, funded by the USGS and other US government agencies.

Categories: earthquakes, geohazards, society

The costs of Trump’s environmental and scientific policies will be felt everywhere

Posted on January 25, 2017 by Anne Jefferson

A post by Anne Jefferson We are six days into the Trump administration in the United States of America and we are seeing clear signs that the Trump intends to keep his campaign promises to roll back environmental protection and federal scientific efforts (among a host of other actions). Hiring freezes, gag orders, spending freezes and more have all been announced already for federal scientific agencies (though some have been temporary). Regulatory roll backs are already underway, two oil pipelines previously stopped have been green-lighted, and there’s more new bad news in this vein every time I check the news. Amidst the news blur, I have also been listening to the voices of Canadian scientists who are frantically trying to tell us that this sounds just like the beginning of the Harper administration and that those of us with tenure (job security) absolutely must speak loudly in protest to stop what we can. I am resolved to do that, and it starts here, with this discussion of jobs, economic costs, and the timescales over which we will collectively be paying for Trump’s actions.

Let the record reflect that it is not just federal and academic scientists who are worried about the news coming out of the early days of the Trump administration. Most of those billions of dollars of EPA contracts and grants go to on-the-ground projects at the city and state level, and effectively support the work people of in city and state government agencies. If the funding for those projects go away, or the federal regulations that are enforced at the city and state levels are loosened, those city and state workers will lose their jobs. And it’s not just public sector workers that will be affected.

I was copied on an email chain this morning populated by folks from the environmental consulting world (i.e., private industry) who are worried about the future of their jobs. I have also heard from several small business owners that they may need to lay off employees or close entirely if their scientific, environmental, and clean energy clients decrease their purchases in response to Trump’s policies. These are all-American, small town businesses worried about going out of business because of the coming changes from the Trump administration.

Lots of “real Americans” are going to lose their jobs if Trump carries through with his plans.

We’ll lose the expertise of people currently working in the environmental and science disciplines and we’ll lose a critical cohort of students who will be deterred from training for science and environmental jobs because of uncertain employment futures. Those that value their scientific careers above their geography will leave the US, and those that can’t or don’t want to leave will find other jobs. Those other jobs will often be lower paying. (I heard “the bike shop” mentioned by a 20+ year career scientist in private industry.) When we eventually get an administration that decides to reverse course and re-prioritize science and environmental protection, we won’t be able to get those seasoned experts or the early career folks back. It’s easy to leave a scientific or technical career, but nearly impossible to get back into one after an absence, but the field moves on and your expertise quickly becomes outdated. Even if many of Trump’s gag orders and freezes end up being temporary, the uncertainty and fear will cause businesses to hesitate in making purchases or hiring staff, working scientists will start looking elsewhere for their next career move, and students will shy away from committing to the rigorous, sometimes decade-long, training it takes to become a scientist or environmental professional.

If Trump carries through with his plans to curtail federal science and loosen environmental regulations, there will be real economic costs that will be felt in nearly every city and state in the country… and those costs will last beyond the end of his administration.

Yes, there may be a short-term economic boost as pipelines are laid and extra smokestacks are built, but that boost needs to have the lost incomes and careers of the scientific and environmental work force deducted from it. Plus, once the pipelines are laid and the smokestacks are built, there will be only a few (often low paying) jobs left.

Of course, the environmental costs of Trump’s plans will be even greater and longer lasting than the direct economic costs. Some industries will take advantage of the looser regulatory environment to do “monstrous” things that will directly impair the public health and ecosystems of the communities in which they are situated. The people most likely to feel the worst effects of increased pollution and land degradation are almost certainly going to be poor and most likely to be non-white. The cumulative effects of many small decisions, even maintaining “business as usual” without malicious intent, will result in poorer air and water quality, more greenhouse gas emissions, and greater climate change impacts than we would have without Trump’s rollbacks. Poor air and water quality and extreme weather and sea level rise fueled by climate change have economic(*) impacts that are increasing every year.

We will live with (and pay for) the consequences of the policy decisions being made right now, for the rest of our lives, and for generations to come.

*I would link to a federal government webpage here as they provide the most definitive data for the US, but government webpages and other communications have a nasty habit of disappearing this week.

(An early version of this post appeared as public Facebook post on my account there on the morning of 25 January 2017.)

Categories: antiscience, by Anne, society

Visualising Earth Structure, redux

Posted on January 20, 2017 by Chris Rowan

Last semester, when teaching my intro class about the composition and structure of the Earth and how we know, I went a bit overboard in producing a snazzy Earth cross-section:

A slightly amended version of my cross-section through the Earth from Kent, OH to its antipode.

I’m still pretty proud of this, but one of its strengths is also a potential weakness: with so much information on offer, it may overwhelm students when they are studying. Which facts are the really important ones? So I’ve been experimenting with distilling the fundamental facts about the Earth’s compositional and mechanical layering into the one true mode of communication in the social media age. I speak, of course, of the animated GIF. Let me know what you think of my first attempts below.

Flashcard animation showing the nature of the compositional layering in the Earth.

Flashcard animation showing the nature of the mechanical layering in the Earth.

Flashcard animation of Earth layers’ radius and volume compared to the whole Earth.

Categories: basics, geology, teaching

Venus stays out in the cold

Posted on January 11, 2017 by Chris Rowan

We basically have a huge generation gap with Venus, and we really need something to launch in the early- to mid-2020s so we can maintain some kind of continuity.”

I’m not a planetary scientist, but I’m still disappointed that two proposed Venus missions lost out to two more (still-interesting looking) asteroid missions in the latest NASA mission selections.

Because I am interested in how plate tectonics works, and in that respect Venus is an important outlier. It is the same size, and has the same basic composition, as the Earth, which means it must have a hot interior and almost certainly has a convecting mantle. But as well as being a lander-melting hellhole, Venus also lacks any obvious plates or plate boundaries; so how does Venus’s internal heat get out? Sending back a radar mapper (which was one of the proposed missions) would offer the intriguing possibility of observing surface changes since the Magellan mission, which might reveal signs of tectonic and volcanic activity. Understanding how it is different is the first step to understanding why Earth became Earth and Venus became Venus – which is an increasingly important question as we start peering towards ‘Earth-like’ exoplanets.

That said, the very nature of Venus makes designing missions that have a good chance of answering that question very challenging. It has taken years of roving on Mars to start getting the basics of Mars’s geological history worked out. It is hard to see such insights flowing so easily from a Venus lander that may last only days.

Categories: planets, tectonics

Anne’s top papers of 2016 + 3 she co-wrote

Posted on January 3, 2017 by Anne Jefferson

Yesterday, I posted an epic analysis of my scientific reading habits in 2016, but I didn’t tell you about the papers I read last year that made my heart sing. And I didn’t take much time to brag about my own contributions to the scientific literature. So I’m going to rectify that omission today.

My top 3 papers of 2016 are (in no particular order):

Of rocks and social justice. (unsigned editorial) Nature Geoscience 9, 797 (2016) doi:10.1038/ngeo2836

The whole thing is absolutely worth reading (and it’s not behind a paywall) but here’s where it really starts to hit home:

Two main challenges stand in the way of achieving a diverse geoscience workforce representative of society: we need to attract more people who have not been wearing checkered shirts, walking boots and rucksacks since secondary school, and we need to retain them.

Waters, C. N., Zalasiewicz, J., Summerhayes, C., Barnosky, A. D., Poirier, C., Ga?uszka, A., … & Jeandel, C. (2016). The Anthropocene is functionally and stratigraphically distinct from the Holocene. Science, 351(6269), aad2622.

Want an up-to-date, data-rich, and condensed summary of why many scientists think it is time for a new geologic epoch? This is the paper to read.

Wu, Q., Zhao, Z., Liu, L., Granger, D. E., Wang, H., Cohen, D. J., … & Zhang, J. (2016). Outburst flood at 1920 BCE supports historicity of China’s Great Flood and the Xia dynasty. Science, 353(6299), 579-582.

I am a sucker for a good mega-paleo-flood story, and this one ticks all of the right boxes. An earthquake generates a landslide, which dams a river, and then fails, resulting in one of the largest floods of the last 10,000 years and alters the course of Chinese history. Geology, archaeology, and history combine in this compelling story.

Plus, a bonus paper, that was definitely one of the best papers I read in 2016.

Shields, C., and C. Tague (2015), Ecohydrology in semiarid urban ecosystems: Modeling the relationship between connected impervious area and ecosystem productivity, Water Resour. Res., 51, 302–319, doi:10.1002/2014WR016108.

I’m cheating a little bit here, because this paper came out in 2015. But I read this paper in 2015, and then I read it twice more in 2016. That’s how much I like it. Why? Because it’s a really nice illustration of how physically-based models can reveal the complex and unexpected ways that ecosystems and watersheds respond to urban environments. In a semi-arid environment, deep rooted vegetation can take advantage of the bonus water that gets delivered from rooftop downspouts that drain out onto the land. The additional water use boosts net primary productivity, potentially enough to offset the loss of productivity that occurred when parts of the landscape were paved and built upon. But while deep rooted vegetation, native to the semi-arid landscape, can take advantage of the bonus water, grass can’t. It’s a cool story, with implications for the way we develop and manage urban landscapes – and the way we model them. (This paper is open access as of January 1, 2017!)

I was thrilled to be able to contribute to 3 papers in 2016.

Turner, V.K., Jarden, K.M., and Jefferson, A.J., 2016. Resident perspectives on green infrastructure in an experimental suburban stormwater management program. Cities and the Environment, 9(1): art. 4.

In 2015, my team published a paper showing how the installation of bioretention cells, rain gardens, and rain barrels on a residential street in the Cleveland area substantially decreased stormwater runoff. This paper represents the other side of the story – the side that is, just as important (if not more so) – how the people on the street responded to the addition of this green infrastructure. In short, getting residents on board with stormwater management is a big challenge that we’re going to face as we scale-up from demonstration projects to widespread deployment of these technologies. (This paper is open access and free to all.)

Bell, C.D., McMillan, S.K., Clinton, S.M., and Jefferson, A.J., 2016. Hydrologic response to stormwater control measures in urban watersheds. Journal of Hydrology. Online ahead of print. doi: 10.1016/j.jhydrol.2016.08.049.

Bell, C.D., McMillan, S.K., Clinton, S.M., and Jefferson, A.J., 2016. Characterizing the Effects of Stormwater Mitigation on Nutrient Export and Stream Concentrations. Environmental Management. doi:10.1007/s00267-016-0801-4

I’m thrilled that first author Colin Bell completed his doctorate in 2016 and got two papers out to boot. These papers are the culmination of 5 years of research in Charlotte, North Carolina. In the Journal of Hydrology, we try to disentangle the effects of stormwater management from the overall signal of urbanization across 16 watersheds. It turns out that for the level of stormwater management we see in the real world, it’s not enough to counter-act the effects of impervious surfaces (pavement and rooftops) as a driver of the hydrologic behavior of urban streams. In Environmental Management, we aim to understand the influence of stormwater ponds and wetlands on water quality in the receiving streams. This turns out to be quite tricky, because the placement of stormwater management structures spatially correlates with changes in land use, but based on differences in concentration between stormwater structure outflow and the stream, we show that it should be possible. This echoes the findings from our 2015 paper using water isotopes to understand stormwater management influences at one of the same sites. Colin will have another paper or two coming out of his modeling work in the next year or so, and we’re still analyzing more data from this project, so keep your eyes out for more work along these lines.