The Shifting Sands Of Our Crustal Earth

On a bright February afternoon in 2001 the technical services team here at Promega received word that a major earthquake measuring 6.8 on the Richter scale had struck the American Pacific Northwest, and that telecommunications with our customers in that region would be significantly disrupted. The major shock had occurred at precisely the moment that one of our own had been on the phone with a researcher in Seattle.  That call was prematurely cut short as electrical power outages and extensive building damage rocked through the Seattle-Tacoma metro area. Fortunately the epicenter of this particular 45-second quake was 52 km below the ground (1). 400 injuries, four of them serious, was the extent of the medical burden suffered. As earthquakes go this was a weak one, although strong enough to rekindle our awareness that the earth beneath our feet is often times worryingly unpredictable (1). This month’s mega-quake in Japan was a painful reminder of the apocalyptic potential of our planet’s extensive seismicity.       

I saw proof of earth’s volatility first-hand in 1992 when I journeyed to the Pacific Northwest to participate in a high school rowing championship in the Oregon-Washington state border town of Vancouver. Traveling along Interstate 5 and looking east I saw Mt. St. Helens, not ejecting a volcanic plume as it had done 12 years earlier in its catastrophic 1980 eruption but ominous nevertheless. Rowing colleagues convinced me that a visit to the volcano would be well worth the effort and would enrich by several orders of magnitude my understanding of the calamity that had unfurled all those years ago. I took their advice and headed out with friends to probe the depths of this particular disaster zone. 

Nothing could have prepared me for what I saw—mile upon mile of downed trees stretching out over slopes that would once have been the terrestrial foundations for growth of lush verdure. One tourist sign en route told of how a steamy 400°F cloud of ash had ravaged the forests as it traveled across the very spot I was standing on at speeds approaching 150 mph. Another explained how an earthquake had prompted the collapse of the mountain’s northern slope. A battered car on the side of the road has been intentionally left as a memorial to two miners who were unable to flee from their cabin as the eruption ensued. But what stood out most in my mind were the historical accounts describing the fascination that gripped many on that fateful day as they witnessed the rumblings of this iconic mountain, seemingly oblivious to the impending dangers. Popular writer Bill Bryson captured the tension of the moment in the following excerpt from his literary tour of science A Short History Of Nearly Everything:

“As the mountain’s rumblings grew, St. Helens became a tourist attraction for the world.  Newspapers gave daily reports on the best places to get a view. Television crews repeatedly flew in helicopters to the summit, and people were even seen climbing the mountain. On one day, more than seventy copters and light aircraft circles the summit…At 8.32 A.M on a Sunday morning May 18th, the north side of the volcano collapsed sending an enormous avalanche of dirt and rock rushing down the mountain slope at 150 miles an hour.  It was the biggest landslide in human history and carried enough material to bury the whole of Manhattan to a depth of four hundred feet…..Many people who were thought to be in safe areas, often far out of sight of the volcano, were overtaken.  Fifty-seven people were killed. Twenty three of the bodies were never found.  The toll would have been much higher except that it was a Sunday. Had it been a weekday many lumber workers would have been working within the death zone” (2).

The grounds are shifting. And we would do well to heed any warning signs that point towards the imminence of disaster. Throughout my travels I have at times observed an outlook of seeming complacency or reluctance to respond in the face of a potential seismic Armageddon. The volcanic giant Tungurahua located eighty seven miles to the south of Quito in Ecuador is a case in point. Living up to its Quichua name ‘Throat Of Fire’, Tungurahua continues to spew molten ash with a ferocity that not infrequently generates ash plumes that tower 2000-5000 ft above its crater (3). In 1999 25,000 people were evacuated from the nearby spa town of Baños as a precautionary measure amidst concerns that Tungurahua was about to undergo a cataclysmic blowout (4). Many whose livelihoods had been forged upon Tungurahua’s farm-fertile slopes were fearful that thieves might descend upon the ‘cash-crop’ of empty properties, and rejected calls to move (5). For some the economic toll of evacuation has become too painful to even contemplate. One sociological study on the Tungurahua relief efforts noted that peasant farmers loose everything from chickens to cattle whenever they ‘abandon ship’ for the safety of more distant communities (6).            

Two years ago the Ecuadorian Geophysics Institute recorded 32 explosions, 30 long-period seismic events and 20 episodes of ‘volcanic tremor’ in one 24-hour period, from the flanks of the Tungurahua crater (4). This is not unusual. I vividly recall driving down one highway in the provincial capital Ambato in 2002 and being stunned by the sight of a towering mushroom cloud billowing high above Tungurahua in plain view of a city going about its daily business apparently unalarmed by the upheaval taking place 40 km away. Volcanologists have used advanced hyperspectral imaging technology to develop detailed topographical maps of Tungurahua that may aid in pyroclastic flow and avalanche prediction projects (7). Across our globe the dual art of predicting the magnitude and timing of eruptions and mitigating their effects has become an increasingly successful affair (8). Scientists can in some cases tap into data from satellites and remote ground-based monitoring stations that capitalize on advances in radar and infra-red spectrometry, to clue in on when the next big eruptions are likely to occur (8). In comparison earthquake prediction technology is lagging behind in its sophistication (9). Even though we have a growing understanding of how our earth’s crust has been carved out and shaped by tectonic movements over vast tracts of geological time, we still cannot, in the words of earthquake expert Thomas Jordan, “predict large earthquakes in a short amount of time with the reliability needed to prepare communities for impending disaster” (9). 

Growing up in the glorious Portuguese coastal town of Estoril just north of Lisbon, I enjoyed many a family afternoon on the beach playing with bucket and spade on the golden sands of this famous tourist trap.  Besides the occasional wailing of fire engine sirens rushing to attend to a forest fire, there was little hint that this part of the world had ever been touched by a natural calamity. History on the other hand tells a different story. In November of 1755 Lisbon was walloped by an 8.7 magnitude earthquake that killed 60,000 people and triggered 5-10 m high tsunamis rivaling in strength those of the Japan earthquake (10). “The tsunami-churning temblor flattened the Portuguese city, killed tens of thousands of people, and caused Enlightenment thinkers to re-imagine the role of government and community” wrote one Associated Press reporter (11). It is not surprising that the scientific literature has touted the Lisbon earthquake as the “greatest natural disaster in recorded European history” (10). The overarching view is that this quake was caused by an eastward subduction of a plate at the African-Eurasian plate boundary close to the straits of Gibraltar (10). The underlying mechanics are such that a large earthquake is predicted to occur in that region every 100-1000 years- hardly the sort of thing that one can realistically plan for (10). 

Sitting down for cake and coffee at our house in Quito years ago my father pointed to a lamp as it swung gently on its chains, leaned over to me and quietly whispered “look at how the earth is moving!”.  He proceeded to reminisce over an earlier visit to Lima in Peru when a 6.0 magnitude ground jolt had startled him (and most of the other guests at our hotel) in the middle of the night. I had slept through this minor event, unaware of the panic that had taken hold in the corridors outside our room. Such occurrences draw attention to our vulnerability as a species and stir up in us the realization that there is much about our control-consumed lifestyles that, truth be told, we cannot control. The shifting sands of our crustal earth remain dangerously capricious.  We in turn remain perilously exposed to its sudden alterations and impromptu adjustments.

 

Further Reading

  1. Greater Seattle Area Rattled By Temblor, Pacific Earthquake Engineering Center Report, Feb 28th, 2001, See  http://peer.berkeley.edu/publications/seattle_feb-2001.html   
  2. Bill Bryson (2003) A Short history Of Nearly Everything, Broadway Books, New York, pp. 220-221
  3. Tungurahua, Global Volcanism Program, Smithsonian National Museum Of Natural History, See  http://www.volcano.si.edu/world/volcano.cfm?vnum=1502-08=&volpage=var
  4.  Erik Klemetti (2010) Activity increasing at Tungurahua in Ecuador, ERUPTIONS: HOT STUFF FROM EARTH’S INTERIOR, See http://scienceblogs.com/eruptions/2010/02/activity_increasing_at_tungura.php
  5. Nancy Sathre-Vogel (2010) Andean village endangered by volcano, Boise Examiner, See http://www.examiner.com/international-travel-in-boise/andean-village-endangered-by-volcano
  6. Graham Tobin, Linda Whiteford (2002) Community Resilience And Volcano Hazard: The Eruption of Tungurahua And Evacuation Of The Faldas in Ecuador, Disasters, Vol. 26, pp.28-48
  7. Ellen Goldbaum (2010) Volcanologists To Fly Over Volcano, University Of Buffalo Reporter, See http://www.buffalo.edu/ubreporter/archives/vol34/vol34n4/articles/Volcano.html
  8. Peter Tyson (1996) Can We Predict Eruptions?  Nova Online, See http://www.pbs.org/wgbh/nova/vesuvius/predict.html
  9. Sally Boorman (2006) Speaker: Predicting earthquakes pose challenges for scientists, Los Alamos National Laboratory News Bulletin, See http://www.lanl.gov/news/index.php/fuseaction/nb.story/story_id/8402
  10. Marc-André Gutscher (2004) What Caused The Great Lisbon Earthquake?, Science, Vol. 305, pp. 1247-1248
  11. Joji Sakurai (2011) Japan tragedy seared into the world’s imagination, See http://news.yahoo.com/s/ap/ap_on_re_as/as_japan_earthquake_global_tragedy
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Robert Deyes

Robert has been a Technical Services Scientist at Promega for over 10 years. He also worked for two years as a Technical Advisor at the Paisley, Scotland facility of Life Technologies Inc. After earning his Masters in Medical Genetics from the University of Glasgow, he spent 18 months at the Université Louis Pasteur in Strasbourg, France where he did research into the molecular basis of the inherited disorder Spinal Muscular Atrophy. He also holds a BSc from the University of Portsmouth in England.

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