Through The Sandglass

Ignoring tsunami records: a "cascade of stupid errors"

In my post last week, examining the evidence of major tsunamis in the past, apparently ignored by the authorities, I chose various options to explain this failing: complacency, hubris, or simply human nature. In the light of reports that have emerged since, I was being generous. From the New York Times last weekend:

Two independent draft research papers by leading tsunami experts — Eric Geist of the United States Geological Survey and Costas Synolakis, a professor of civil engineering at the University of Southern California — indicate that earthquakes of a magnitude down to about 7.5 can create tsunamis large enough to go over the 13-foot bluff protecting the Fukushima plant.

Mr. Synolakis called Japan’s underestimation of the tsunami risk a “cascade of stupid errors that led to the disaster” and said that relevant data was virtually impossible to overlook by anyone in the field.

The Fukushima Daiichi nuclear plant was built on a 4-meter coastal bluff and “protected” by sea walls, largely designed for typhoon waves, not tsunamis, that were 5.5 meters in height. The tsunami that struck the plant was 14 meters high.

Masataka Shimizu, the President of Tokyo Electric Power, described the tsunami as “bigger than our expectations” and put the blame for the catastrophe on mother nature. “We can only work on precedent, and there was no precedent,” said Tsuneo Futami, a former Tokyo Electric nuclear engineer who was the director of Fukushima Daiichi in the late 1990s. “When I headed the plant, the thought of a tsunami never crossed my mind.”

These kinds of statements (and there are many more) are totally stupefying. This is not just stupidity, it is, arguably, criminal stupidity. In 2009, one of Japan’s leading seismologists, Yukinobu Okamura, warned that research called into question the assumptions underpinning the plant’s design, telling safety review meetings convened by the Nuclear and Industrial Safety Agency that “it’s now known that [tsunamis] of a completely different scale have come before.” Some of the evidence he was referring to came from the research, published in 2001, that the earthquake of 869, estimated magnitude 8.3, had caused an 8 meter high tsunami that inundated the Sendai coastal plain for  a distance of more than four kilometres inland; the evidence came from the extent of sand deposits left by the tsunami. No precedent?

Now, to be fair, in 2002, the Power Company had taken action - “raising the level of an electric pump near the coast by 8 inches, presumably to protect it from high water, regulators said.”

Following Mr. Okamura’s repeated warnings, the authorities only agreed to to consider the issue further – the topic of tsunamis was not on the agenda for the meeting. As reported in the Financial Times “ ‘We did not ignore tsunami issues but we thought it was not the appropriate place to talk about it,” the company said. It added, however, that it was unsure what the proper place for discussion of tsunami risk might have been.” See what I mean by stupefying?

The entire approach had been to choose historical precedents that were convenient, if not relevant, to make the totally false assumption that earthquake magnitude correlates with tsunami size, to fail abysmally to respond to expert evidence, and to attempt to bluster (a euphemism that I choose for the sake of objectivity) their way out through bureaucratic excuses. “A cascade of stupid errors.”

And there’s more:

The Japanese approach, referred to in the field as “deterministic” — as opposed to “probabilistic,” or taking unknowns into account — somehow stuck, said Noboru Nakao, a consultant who was a nuclear engineer at Hitachi for 40 years and was president of Japan’s training center for operators of boiling-water reactors.

“Japanese safety rules generally are deterministic because probabilistic methods are too difficult,” Mr. Nakao said, adding that “the U.S. has a lot more risk assessment methods.”

I can’t think of a more generous description of this than as complete rubbish. Probabalistic methods of risk assessment are common practice in a vast variety of situations and are hardly rocket science. They simply involve using evidence of the known variability in the key parameters determining the outcome of a complex phenomenon and running these through a large number of possible combinations to yield a statistical range of possible outcomes. That range – of size of outcome versus the probability of it occurring – can be depicted as a size versus probability graph like this:  This kind of shape is typical of natural events: earthquakes, storms, floods – and tsunamis. A high probability (or frequency) of “typical,” modestly sized occurrences but with the possibility of very large, “unusual” events. This is “the long tail” of rare events that are, nevertheless, consistent with the range of known parameters that conspire to cause them. The realistic possibility (particularly given the historical and geological records) of a 14-meter tsunami would not be far down that tail.

This is not rocket science – it is not “too difficult.” This is a methodology that many of us use routinely professionally on a regular basis – a simple means of doing this is available through Excel-based software. “Too difficult”? “Too difficult” when the lives of hundreds of thousands of people and the safety of a major nuclear facility are at stake? This is Japan, for crying out loud. This would be pathetic if it weren’t so utterly callous.

 

Sunday sand: Bali's bounties

I wrote a bit about the sands of Bali last year, particularly the foram grains. But Bali is one of those places where the sands, reflecting, as always, the local ingredients, are diverse and bring together the products of geological and biological activity. The island is, after all, a volcano, and some beaches are clear evidence of that – sparkling grains of volcanic glass, lava fragments, and apple-green olivine crystals.

When I wrote that earlier post, little did I suspect that I would have a personal reason to reflect on the diversity of sands that Indonesia’s sprawling archipelago has to offer. I lived and worked in Indonesia a long time ago, and developed a great fondness for the place and the people; I returned recently to work on a project for the last month or so, and this has now turned into something longer term. So I’m now back briefly to London to get organised before returning to Jakarta together with Ibu Sandglass. All this may cause some disruption in blogging continuity for a while, but I look forward to reporting on this new adventure – and, hopefully, being able to describe the occasional personal encounter with my never-ending topic in this wonderful part of the world.

 

[Bali beach image, http://www.newshotram.com/wp-content/uploads/2010/08/Bali-beach-sunset.jpg]

Ignoring tsunami records: hubris, complacency, or just human nature?

The earthquake that struck Japan may have been the largest since historical records began (and the fourth largest ever recorded), but the tsunami had many precedents – bigger ones – in the historical and geological record. The size of a tsunami is related to the displacement of the seafloor, not necessarily the magnitude of the earthquake, and significantly smaller events than the one on March 11th have generated larger tsunamis. This raises two questions: given the size and devastation of past events, why should this have been a surprise and why were “defences” so woefully inadequate? And, are there, realistically, such things as “tsunami defences” at all?

These are questions that countries beyond Japan should also be asking themselves.

I have put off writing anything about the catastrophe, in part because the geoblogosphere has been doing its typical comprehensive job (see Dana Hunter’s links as a good starting point), but also because I was, I suspect like many of us, simply mesmerised by the surreal and incomprehensible scenes that unfolded, day after day, through the unprecedented documentation of the tragedy. But now I have begun reflecting on one of my earliest posts, “Tsunami forensics - sand helping save lives,” and concluded that we would seem to have a long way to go; if hubris, complacency, and other human foibles led to a failure of thinking and planning in Japan, then where is the hope for less developed (or even equally developed) parts of the world?

First of all, following up on the theme of my post on the forensics of sand deposits documenting past tsunamis in Thailand and Sumatra, I easily located a couple of examples of the same kind of work that has been conducted, hardly surprisingly, in Japan. In their article, “Geological Study of Unusual Tsunami Deposits in the Kuril Subduction Zone for Mitigation of Tsunami Disasters,” Japanese researchers describe meticulous analysis of tsunami sand deposits covering the last 5,000 years from Hokkaido, north of the recent events; the sands are carefully dated, and their internal structures used to shed light on the flow regime of the tsunamis that deposited them. They observe that “Only when an unusual tsunami strikes coastal lowlands does a large-scale sediment transfer occur, leaving a sedimentary record, that is, tsunami deposits, in the geological strata on shore.” And they calculate, from the multiple tsunami sands preserved, the average recurrence interval of “unusual tsunamis”: every 220-379 years over the past 5,000. They conclude that “The geological information obtained by this study is valuable for mitigation of tsunami disasters.” Well, maybe.

 
Similar recent studies have been done in other areas of Hokkaido. For example, “Aperiodic recurrence of geologically recorded tsunamis during the past 5500 years in eastern Hokkaido, Japan” (only the abstract is publically available) documents that “The sand sheet extents suggest that most of these tsunamis were larger than any generated at Hokkaido in the last 200 years. The intervals between these inferred outsized tsunamis average nearly 400 years but range widely from about 100 to about 800 years.” Bear in mind these intervals – 100 to 200 years are entirely possible – in the context of historical events. 

Of course, I couldn’t help but be curious about a paper with the title “A Huge Sand Dome Formed by the 1854 Earthquake Tsunami in Seruga Bay, Central Japan.” This is a geological study of tsunami sand deposition as a result of a historically documented event. Seruga Bay is not far south of Tokyo, and the 1854 tsunami was devastating; here’s the abstract of the paper:

The 1854 Ansei-Tokai earthquake brought massive destruction to Suruga Bay, central Japan. The earthquake triggered a large-scale tsunami, which surged over the Pacific coast of Japan. Waves exceeding 13.2 m in height attacked Iruma, southeastern coast of Suruga Bay, and provoked peculiar types of tsunami sedimentation. On the coast of Iruma, a huge mound of shoreface sand, reaching more than 11.2 m above sea level, appeared after the tsunami run-up. We performed a historical and sedimentological survey to clarify the origin of the mound. Result of a field excavation and submarine
investigation suggests that the sand came from the seafloor with a water depth of 20 to 30 m, and historical data illustrates a dramatic change of the landform by the tsunami run-up. Numerical examination of the tsunami implies that the coastal topography played an important role in excitation of the tsunami, and it induced the characteristic tsunami sedimentation.

“Waves exceeding 13.2 meters.” Here’s the town of Iruma today, completely rebuilt on top of this gigantic pile of sand:

Mass transfer of sediment by a tsunami causes wholesale changes to coastal topography, and when the shape of the coast resonates with, and amplifies, the character of the tsunami wave, the effects can be dramatic. Among the compelling images of the last ten days are the series of “before and after” images, of which fascinating (and depressing) examples are from the New York Times and Picasaweb. Any number of these illustrate coastal change and the shifting of huge amounts of sand. Here, for example, the coast near Ueda, south of Sendai:

But this is only part of the story of coastal change. The wholesale physical displacement of Japan as a result of the earthquake is, even to a geologist, astonishing. Callan Bentley reported GPS data showing a lateral movement of 4.4 meters and he points out the less widely reported, but in many ways more significant vertical subsidence of up to 75 cm along some parts of the coast. But now, as if these figures weren’t dramatic enough, Japan’s Geospatial Information Authority in Tsukuba are reporting that the Oshika Peninsula that lies closest to the epicentre has moved 5.3 meters and dropped 1.2 meters since the earthquake – records for Japan. Scrutinise the before and after images, and evidence of coastal subsidence as well as erosion, becomes apparent. Consider these images of the Yamamoto coast, not far from Sendai:

 
But, for me, the greatest drama is apparent in images from the area of Ofunato and Otomo, a hundred kilometres north of the Oshika Peninsula:

Look closely and compare – the entire coastline appears to have sunk (even allowing for the fact that the relative state of the normal tide in the two images is unknown). The town of Otomo is at the left in each image; a seawall is apparent across the bay “before,” but has completely disappeared – and would seem to be buried in sand – in the post-tsunami image. The devastation in these towns was almost total and rescuers are still struggling to even access them. Here’s another pair of images – are we seeing an enormous sand deposition event similar to that at Iruma in 1854? Was there also a resonance between the shape of the coastline and the tsunami that amplified the potential for catastrophe?

 
That potential for catastrophe certainly becomes greater if the subsidence of the coast as a result of the earthquake is taken into account. A seawall, such as that supposedly protecting Otomo, instantly drops by a meter, its height rendered even less effective against an unusual tsunami. And it’s not as if this stretch of coast had not experienced “unusual tsunamis” before – you don’t even have to dig into the geological record. In 1896, an earthquake whose magnitude is estimated as 7.2 – in other words, not at the worst end of the scale – caused a reported 25 meter tsunami. And the 1933 8.4 magnitude earthquake caused a tsunami described as 28 meters high. The scale of a tsunami is very much dependent on the shape of the coast, not necessarily the magnitude of the earthquake.

The recorded history of Japan’s coast is filled with accounts of “unusual tsunamis” – David Bressan has an excellent summary. Look into the sedimentary record, and the evidence continues: around Sendai, five tsunami sands are found up to four kilometres inland; along the coast near Ofunato and Otomo, up to 113 sand layers record major tsunamis – some of them from elsewhere in the Pacific. These figures come from the presciently titled book by Edward Bryant, Tsunami – The Underrated Hazard (published in 2001 and now extremely expensive, but available on Google books). As Bryant writes, “the stratigraphic evidence designates this coastline as the most frequently threatened inhabited coastline in the world.” Indeed.

So how, when the historical and geological evidence shows so clearly that devastating tsunamis hit a sinking coastline with a frequency that hardly labels them as “black swans,” could such a catastrophic loss of life – not to mention a nuclear emergency - as we have been witnessing possibly occur?

There is, clearly, no simple answer, but part of the problem would seem to be a level of complacency that is not, unfortunately, atypical of human nature. Take the seawalls, for a major example. As a piece in the New York Times reported, “At least 40 percent of Japan’s 22,000-mile coastline is lined with concrete seawalls, breakwaters or other structures meant to protect the country against high waves, typhoons or even tsunamis. They are as much a part of Japan’s coastal scenery as beaches or fishing boats, especially in areas where the government estimates the possibility of a major earthquake occurring in the next three decades at more than 90 percent, like the northern stretch that was devastated by Friday’s earthquake and tsunami.” But the article goes on to say:

A fuller picture of how seawalls protected or failed to protect areas beyond the nuclear plants will not emerge for at least a few more days. But reports from affected areas indicate that waves simply washed over seawalls, some of which collapsed. Even in the two cities with seawalls built specifically to withstand tsunamis, Ofunato and Kamaishi, the tsunami crashed over before moving a few miles inland, carrying houses and cars with it.

In Kamaishi, 14-foot waves surmounted the seawall — the world’s largest, erected a few years ago in the city’s harbor at a depth of 209 feet, a length of 1.2 miles and a cost of $1.5 billion — and eventually submerged the city center.

“This is going to force us to rethink our strategy,” said Yoshiaki Kawata, a specialist on disaster management at Kansai University in Osaka and the director of a disaster prevention center in Kobe. “This kind of hardware just isn’t effective.”

We are all now numbed by the videos of the tsunami not only crashing over seawalls, but destroying them – videos taken by residents who may well have assumed that they could remain, protected by those defences, residents who were lucky to have survived. And then look at the before and after images of Otomo, above: a seawall not only rendered useless, but consumed.

Again, from the New York Times article: 

The height of seawalls varies according to the predictions of the highest waves in a region. Critics say that no matter how high the seawalls are raised, there will eventually be a higher wave. Indeed, the waves from Friday’s tsunami far exceeded predictions for Japan’s northern region.

And, for a mind-numbing example of tragic complacency, watch this BBC video of the Fire Chief of the town of Rikuzentakata, just SW of Ofunato, describing how a tsunami two years ago damaged the seawall. His warnings went unheeded, and, on the 11th March, 45 of his crew were lost trying to close the harbour gates by hand.

I simply don’t understand how, given even the sampling of historical and geological records above, what the “predictions” that were "far exceeded" could possibly have been based on, and how there could have been the total lack of imagination that allowed them to be regarded as definitive. And then there’s the reliance on the – tragically inadequate – seawalls protecting the nuclear power plants. Couldn’t someone, even years after the construction of the plants, have said, in the spirit of over-engineering where failure could have catastrophic consequences, “There is a scenario, not impossible to conceive, in which the seawalls would fail – just to be safe, why don’t we put our generators and pumps, the switchboards and backup systems, on top of an impregnable fifty-foot reinforced concrete structure?” Or something to that effect.

Maybe I’m over-simplifying things, maybe not….

Update: since I wrote this post, I have been in touch with my geologist friend, Rovicky (who writes his own blog on these kinds of things and many other matters geological - in Indonesian) and he provided me with yet another paper on reconstructing ancient Japanese tsunamis from sand deposits. This is from studies of the Sendai area, one focus of recent devastation. Titled "The 869 Jogan tsunami deposit and recurrence interval of large-scale tsunami on the Pacific coast of northeast Japan," the abstract is as follows:

The fore-arc region of northeast Japan is an area of extensive seismic activity and tsunami generation. On July 13, 869 a tsunami triggered by a large-scale earthquake invaded its coastal zones, causing extensive deposition of well-sorted fine sand over the coastal plains of Sendai and S ma. Sediment analysis and hydrodynamic simulation indicate that the tsunami inferred to be triggered by a magnitude 8.3 earthquake spread more than 4 km inland then coast. We postulate that the sand layer was developed by the tsunami’s first wave. Traces of largescale invasion by old tsunami as recorded in the coastal sequences of the Sendai plain show about a 1000-year
reoccurrence interval. We suggest that the J gan tsunami was much larger than tsunami generated by normal earthquakes in the subduction interface.

The paper would normally be available online from the Japanese National Institute of Informatics, but at the moment, the site sadly simply contains the following note: "NII services is currently unavailable due to a scheduled blackout in connection with the Japan earthquake. Sorry for your inconvenience." If anyone is interested, I can email a pdf, thanks to Rovicky.

 

[For an interestingly different approach to tsunami shelters, and other approaches, see this report from the New Scientist. And for further reading on earthquake and tsunami - and general - hazard assessment, see http://blogs.agu.org/landslideblog/2011/03/15/from-a-geological-perspective-what-is-surprising-about-the-sendai-earthquake/. For a mesmerising display of the - at the time of writing - more than 600 aftershocks, visit http://www.japanquakemap.com/]

 

Sunday sand - not

What can these colourful grains be? Clearly a variety of rock-types, quite angular but showing signs of smoothing and abrasion. Some limestones? Green chert, perhaps? Dark basalt? And turquoise?

Well, actually, no. A colleague where I’m working just returned from taking his 82-year-old mother on the “Mini-Haj” in Mecca (he had spent some time in advance getting into shape so as to be able to push her wheelchair the necessary distances). When he saw these in Mecca, he thought of his geologist friends and brought them back – they’re candies/sweets, chocolate inside, a sugar colourful glaze on the outside. And they are granule-size, not sand. So this post is entirely a hoax, a bit of perhaps much-needed fun – and they are good!

Guest post: A Museum with Sands

Finally, a voice other than mine again: this from Kate Clover, Gallery Manager at the Science Museum of Minnesota:

A Museum with Sands

There is a collection of vials with sands on exhibit at the Science Museum of Minnesota in St. Paul. The collection includes sands from around the world that has been donated by staff and visitors and friends and brought into the museum in baggies, chip bags, pop bottles, mint tins, medicine vials, and cigarette wrappers. The sands have been collected from lakes, rivers, seas, oceans, deserts, dunes beaches, quarries, backyard sandboxes and playgrounds—green sand, red, black, white, and generic brown sands. From the ABC of countries: Argentina, Bulgaria, Canada, Denmark, Ecuador, Fiji, Greece . . . and every state in the US—nearly 1000 samples and ever growing!

 

This case showcases a small number of the sands on exhibit at the museum. Stereo microscopes are used for viewing sands. Photograph by Kate Clover

The sand collection is displayed in the museum’s Collectors’ Corner, a trading post where visitors of all ages can trade their found objects from nature for other things —rocks, shells, skulls, bones, insects, and yes—sands. Traders are awarded points for their objects and their knowledge, and then they can use their earned points to “purchase” other things. It’s a successful program. The program encourages people to engage in science in their homes, parks and in their travels and to dig a little deeper to broaden their knowledge of the world. The program engages learners at their own level and encourages life-long, life-wide and life-deep learning. http://www.smm.org/visit/collectorscorner/

In addition to trading sands, visitors can use stereo microscopes to examine sands and view poster-size photographs of sands magnified 225 times. The photos by Dr. Gary Greenberg (www.sandgrains.com) illustrate the stunning beauty and intricate nature of sea urchin spines, glass sponge spicules, shells and forams as well as colorful mineral grains. Visitors stand in awe in front of the photographs and comment about the diversity of colors, textures and mineral or biological grains. At the display of vials, they seek to locate their hometown beaches and favorite beach vacation destinations. Foreign visitors look for sands from their home countries.

 

Dr. Gary Greenberg’s photograph of sand on display in the Collections Gallery at the Science Museum of Minnesota. Photograph by Kate Clover

Gallery manager Kate began to assemble the sand display from her personal collection in December 1999. Initially, museum staff expressed skepticism about the sand display idea, but today, it’s a visitor favorite within the museum. Everyone has some experience with sand, and looking at sand under a microscope offers a new way to explore and understand a region’s geology or marine ecology.

Why do people collect? I believe our inquisitive nature is behind our impulse to collect objects. In collecting, we try to make sense of the rocks, shells or sands and their place in the geological or biological history of the earth. Maybe this learning doesn’t happen at first, but the more one collects, the more one sees the variables and begins to ask questions: why? where? how? Our goal at the museum’s trading post is to encourage learning and to instill a value to the scientific significance of the things kids collect. Science is about observing; it’s fun, exciting and engaging. The objects in our collections teach.

Heavy mineral sand from Lake Winnibigoshish, Minnesota

Mention Lake Winnibigoshish, more commonly known as Lake Winnie, to Minnesotans and you’re likely to hear fishing tales of northern pike, walleye, bass and muskellunge—not sand.

This stunning photograph of sand grains from Lake Winnibigoshish in north-central Minnesota shows the vivid, exquisite beauty that sand grains can show when viewed under the microscope.  Many of these grains are garnets, miniature gems!

 

Sand from Lake Winnebigoshish, Minesota. Photograph by Dr. Gary Greenberg. Used with permission.

These sand grains originated billions of years ago in the rocks of northern Minnesota and Canada. After as many as a million years and multiple cycles of weathering and transportation, the rocks have broken down into rounded grains like we see in this photograph. This sand was most probably collected from a dark swath on the beach where the action of the waves naturally concentrates denser minerals like garnet and magnetite.

Grains in this Sand

•  Garnets:  This sample includes both pink and orange garnets.

•  Quartz: Quartz grains in this sample are colorless to cloudy white, rounded and polished.

•  Magnetite, Ilmenite, and Hematite: These iron minerals appear opaque and range from black to red.  Along with hornblende (which also appears black), these minerals make up nearly half the sand grains.

•  Epidote: The pistachio-green grains are epidote.

•  Diopside:  The dark glassy green grains are diopside.

• Zircon: The faceted bluish grain near three o’clock is likely a zircon.

The Rock Hard Café features an eclectic menu.

There’s some whimsy at the Collectors’ Corner too. Check out platters of food at the Rock Hard Café where spilled ice water is depicted with calcite rhombohedrons and a sheet of mica, azurite nodules are blue berries, and green olivine sand is guacamole served with ribbed cockle shell chips. There’s more sand in the spice rack too: yellow sand “curry,” red sand “paprika,” white sands “salt”, black sand “pepper,” generic brown sand “cumin.” Next time you’re in town, check out our Rock Hard Café!

 
This Lake Superior beach shows streaks of heavy minerals, including magnetite and garnet. The pebbles are dark basalt and reddish rhyolite. Photograph by Kate Clover

 

[Kate and I began our virtual conversation after I had posted a Sunday Sand piece on Easter Island. She sent me a photo from her collection of a very different sand from the island – clearly volcanic fragments from the rocks that the island is built from. I discovered that she runs this great program at Minnesota’s Science Museum and asked if she would write a guest post, which she did – many thanks, Kate! And please note that Through the Sandglass would be delighted to host other guests – the more the merrier, so don’t hesitate to get in touch.]

Christchurch liquefaction - an eyewitness story

When an earthquake strikes, the normal, and reassuring, sense of terra firma vanishes instantly. This is caused by not one, but often two, potentially devastating impacts of the earthquake: the shaking itself and, if the subsurface is unconsolidated and water-logged sand, liquefaction. I have written about this phenomenon, the complete loss of strength and support for the foundations of buildings, before, in the context of the Loma Prieta and Haiti earthquakes. And now, through one of those odd series of connections that occur far less rarely than one expects, I have received a very personal account of liquefaction associated with the recent Christchurch earthquake.

I’m working in Jakarta at the moment, and recently got together with an old geologist friend whom I hadn’t seen in a long time. As the catching-up conversation hurtled from one topic to another, it turned out that, until not long ago, he had lived in Christchurch, and that a mutual colleague still does  - and has experienced major liquefaction events in both the earthquake of last year and this latest, tragic, one. Specifically, sand volcanoes had erupted on his property in both earthquakes. This, of course, led me to exclaim (for once, that word seems quite appropriate) that this topic was of some considerable interest to me, and I have now been in touch with my erstwhile-colleague in Christchurch. The account and the photographs that he has sent me are extraordinary, and he has kindly (given how much else of somewhat greater importance he has on his mind right now) allowed me to reproduce them here.

Admirably, he ran a brewery in Christchurch – I say “ran” because it was only a couple of blocks away from the collapsed building that tragically trapped so many people. Here’s how he described the event:

I was in the brewery weighing out hops. The building is still standing, though we have sustained some structural damage, parapet walls down and large cracks in the walls (not to mention all the fallen bottles and barrels and broken glass) was all that I could see before we evacuated the area. All the customers and staff were uninjured though it was terrifying and the mess that I glimpsed before I left is much much worse than last time.

In a later email he describes how he has had to make his staff redundant and has “No idea when if ever we will be allowed back into the CBD.” The Central Business District (CBD) remains cordoned off.

As for the liquefaction and sand volcanoes at his home, the effects are incredible:

 
He commented that

It seems churlish in a way to moan about the state of our garden while people are still being pulled from the rubble, but ironically just this last weekend Lisa's parents finished cleaning up the last of the sand from the September earthquake and now it is all back in EXACTLY the same places. Another 100 tons or so to remove! Our wooden house has survived well again, although I am sure it must have sunk and bent a bit more, but we can still live in it.

Aftershocks continue to shake the house as I write this email. I still have dust and bits of masonry in my hair!

“Another 100 tons or so”! But then, when you look at the extent of the eruptions, this seems like a possible underestimate. Here are a couple of photos of the last clean-up, followed by more of the current mess.

 

I wrote to my old colleague that “While I deeply regret the spontaneous deposition of tons of my favourite material yet again in your garden, your photos are fascinating” – I hope readers will agree. I guess that geologists must be phlegmatic about natural processes impacting their lives, but this would push me (and most certainly my wife) to the limit. So thanks, Martin, and very best wishes for re-building (and re-clearing).

 

[See a compelling video of liquefaction in a wheelbarrow as the results of arenaceous volcanicity are cleaned up in Christchurch; Chris Rowan at Highly Allochthonous has a kept an excellent series of posts on the earthquake updated, here and here. See also an excellent and graphic summary of Christchurch liquefaction as a pdf by the local government, and New Zealand Sciblogs have a description of the process and of sand “boils.”. The New Scientist has a good summary of New Zealand tectonics. As for what might conceivably be done to reduce the effects of liquefaction, see my post on the remarkable skills of bacillus pasteurii.

Accretionary Wedge # 32

The March edition of the Accretionary Wedge geoblog carnival is at Ann’s Musings, and the theme is a deceptively simple summons: “Throw me your ‘favorite geologic picture’ mister.”  This is nigh-on impossible and has led to some considerable introspection, not to mention scrabbling around to see what candidates I have with me on my laptop. But the scrabbling stopped as soon as I reminded myself of the image above. At first glance, perhaps it’s not strictly geological – but then again, yes it is. And, because of the very personal impact, it’s one of my favourite pictures – ever.  

It’s from a location in the remote south-western corner of Egypt, a Louvre of rock-art. This is just a small exhibit in a cave shelter covered in human expressions. The setting is geological, the canvas is geological, and the materials are geological, and all combine in the message of the connection between humans and geology. But of course it’s even more than that – we have no idea really who the artists were, exactly when they lived, what the function of this place was in their society, or why they expressed themselves so exuberantly. But the emotional  resonance, sitting there gazing at this, has become deeply ingrained; there is an immediate, intensely human, connection with two unknown people who chose to record their hands reaching out to each other.

It’s not even a picture of sand – but it is probably my favourite geological photo. And, in today’s world, perhaps it has an important message.

Sunday sand: a geological anthology of Rhodes

I’ll leave this beautiful sand to speak for itself. It’s from Apolakia Beach on the west coast of Rhodes in the chain of Greek Islands, the Dodecanese. This multi-coloured diversity of grains is a geological anthology of the island’s dynamic origins, set as it is amidst the tectonic turmoil of the eastern Mediterranean. It reminds me of the variety displayed by the sand of San Francisco’s Marshall Beach, a similar compilation torn from similarly tectonically tortured terrains.

 

 

[This sand is from my old arenophile friend, Loes Modderman]

Deepwater volcanic sand overturns conventional wisdom

We have long known of volcanic activity deep below the surface of our oceans, the processes that provide the new material for oceanic crust as it spreads away from the mid-ocean ridges and carries the continents along with it. The chains of volcanic mountains such as Hawaii, greater in their relief than Everest, and the volcanic seamounts scattered across the ocean floors. All this has been in the textbooks for decades, as has been the obvious fact that deepwater volcanic eruptions are rather benign and unspectacular events, their energy constrained by the overpowering pressure of the water. Obvious, that is, until recently.

The conventional wisdom that “these eruptions burbled gently rather than bursting in fiery explosions” has now been shown to be wrong, largely as a result of the work of David Clague, a geologist at the Monterey Bay Aquarium Research Institute (MBARI) – but it took an awful long time for his results to be accepted. The story is told in some detail in a recent MBARI press release, and it makes fascinating reading, for the research itself, but also for the all-too-common challenges of overturning conventional wisdom. And, as you might have guessed, sand has a role in the story.

Back in 1997, Clague was studying Loihi, Hawaii's youngest underwater volcano, diving in a deepwater submersible from the Hawaii Undersea Research Laboratory. As the press release describes:

“An explosive eruption basically produces a lot of little tiny particles,” says Clague. While the smaller dust-sized particles blow away on the currents, larger sand-sized pieces settle closer to home. When the Pisces submersible crested the lip of Loihi's newly formed crater, Clague saw black sand rubble everywhere. “That was indicative of fairly abundant, or common, explosive activity on Loihi,” Clague says. “What we learned was that it’s actually a pretty common event there, and that Loihi is a quite explosive volcano.” 

The sand is shown in the photo at the left of the header image, settled between the outcrops of lava. The central photo shows the simple – but critical – approach that Clague used for sampling. Traditionally, such deepwater volcanic environments had been sampled using a dredge haul or similar techniques designed to collect large chunks of rock – nothing sampled the finer material. So, in 2000, Clague returned, using push cores and suction sampling to collect the sand and finer sediments. His analyses confirmed what he had observed on the original visit to the sands of Loihi – that they contain large amounts of limu o Pele, “Pele’s seaweed.” This delightful term describes the thin sheets and flakes of volcanic glass that are produced by bursting gas bubbles within an erupting lava; Pele is, of course, the fire goddess of Hawaiian volcanoes, whose wrath is incurred should you ever sample any sand from the islands; there is also “Pele’s hair,” threads of volcanic glass, and her tears. Limu o Pele and Pele’s hair are shown in this image from the MBARI article (Jenny Paduan © 2011 MBARI):

 
Now Pele’s seaweed and hair are commonly found where lavas flowing into the sea from an emergent volcano such as Kilauea mix with sea water that is instantly turned to steam and explosions on all scales. But they had never before been observed associated with deep water volcanoes – could these eruptions in fact be far more violent than had been assumed? The answer, as Clague was eventually to prove, is yes. But his findings, when they were first published in 2003, were essentially ignored:

It wasn’t until 2009, when a research team led by Robert Sohn of the Woods Hole Oceanographic Institute published similar findings in the high-profile journal Nature, that geologists finally began to accept that deep-sea volcanoes could erupt energetically… Sohn's paper was the clincher that solidified this new view of underwater eruptions.

It also helped that expeditions finally began to encounter, and capture images of, live eruptions of deepwater volcanoes. I wrote in my last Sunday sand post of the tectonic chaos of the southwest Pacific, and the Islands of Samoa. A clear demonstration of this chaos is the active volcanism going on continuously in the region, and it was from the West Mata volcano, a couple of hundred kilometres southwest of Samoa and whose peak lies more than 1000 meters below the ocean surface, that some of this dramatic evidence came in 2009. Explosive volcanic eruptions at this great depth – see the photo at right in the header image (Joe Resing/NOAA/NSF) and absolutely go to http://www.youtube.com/watch?v=hmMlspNoZMs&feature=fvwrel for some stunning video (narrated by Resing).

So, simply by David Clague’s sampling the previously un-sampled, and questioning conventional wisdom, we now know something new about how our Planet actually works – better late than never.

And, speaking of sampling and Samoan sand, among the grains of the latter were foraminifera: I’ve written often about these critters before, including the ones that build their shells out of other grains, the so-called agglutinating forams. The photo below shows one such foram, about 2mm across, that specialises in building its shell from limu o pele, and, as David Clague writes:

Benthic foraminifera often glue particles to their tests, perhaps for protection from predators. These particles may be sponge spicules, sand grains, or other detritus, depending on the materials available and the "specialty" of the foram. In sediment cores from the Gorda Ridge [off the coast of Oregon], we found forams that "specialized" in volcanic glass grains and others that "specialized" in limu o Pele. They effectively concentrated the glass samples for us!

 

[All images not credited in the text © MBARI]