A pursuit of the explosive debate set to shake climate science: can we expect a geospheric retaliation to be another outcome of anthropogenic climate change?
Scott Owen hosts a radio podcast and YouTube channel called 'Believers Underground'. The primary topic he covers is the post-glacial rebound theory and he has been called upon to explain this phenomenon in several online videos. Owen often alludes to pessimistic notions of sinking landmasses however his justifications about post-glacial melt impacts is intriguing. A particularly useful broadcast to listen to features Scott Owen as a guest on another online climate channel talking about isostatic rebound in response to glacial melt.
I have included a link to the Believers Underground blog site below. The particular podcast that I have linked is one i recommend as it covers the elaborate topic of MEGA quakes and SUPER volcanoes! Scott Owen takes a decisive controversial stance whereby he candidly blames the elite's disregard for humanity for destroying our planet.
I have come to notice that there is very meagre amount of attention on the internet to the field of climate change science surrounding its potential to increase the frequency of catastrophic events. It is somewhat surprising that despite #climatechange being amongst the top ten trending topics on twitter in 2011, I have struggled to find electronic awareness on the geological impact. Having said this, this realm of science remains in its infancy having been first pioneered only relatively recently. Out of the few mentions I found on twitter, below is an example of futurologists are beginning to introduce the concept:
Terminology such as 'isostatic rebound' are only just being incorporated into climate change discourse. Obviously, the science behind global warming causing more extreme weather conditions (hurricanes, droughts etc) is thoroughly tested and widely acknowledged. However surely when this idea was first proposed it took a while before it was understood and accepted? Whilst awareness appears to be lacking on geological impacts, already keen scientists are managing to provoke interest by means of twitter:
'Global Rumblings' is a compelling blogspot site which asks - '2012 - Will it change the world as we know it? Why so many earthquakes? Tornadoes? Disasters?' Its purpose is to provide commentary on the causes, impacts and patterns of contemporary disasters. The aptly titled blog focuses on earthquake activity however extends to all forms of worldwide disturbances ranging from supervolcano eruptions to fireballs in space. Global Rumblings appears to be the primary source for up to date hazard information in the blogosphere and one particular reason for its mention is for the post 'Earthquakes and Climate' which was posted in March 2011. This segment was written two years after the author first theorised about earthquakes and climate in an article published in 2009. Within the two years, a significant amount of work has been done (enough in fact to allow me to produce a blog solely dedicated to the research) that shows the field of science is growing. Given another two years I predict far more evidence will have been obtained and the topic's obscurity will be a thing of the past.
Today I came across a fascinating website produced by the Incorporated Research Institutions for Seismology (IRIS) that allows the user to check out all the latest earthquake activity. Whilst not alluding to the mechanisms that trigger the quakes (i.e. climate change), the website is an invaluable tool for anyone interested in keeping up to date with global seismic activity. Having browsed the earthquakes of the last 30 days, I was startled at the number of unreported earthquakes that are taking place each day. For example, it is barely 10 am and already there have been five recorded events this morning - including a magnitude 5.2 in Fiji Islands as well as a 6.6 in Russia yesterday evening. I then scrolled down and noticed a shocking 11 earthquakes struck on christmas day; four of which were in Japan.
Theoretically, I was aware that magnitude 4-5 quakes were happening regularly within tectonic zones, but this website put seismic activity in perspective for me. When looking at the IRIS Seismic Monitor map, spatial distribution of earthquake activity is easily discernible, and by marking the quakes in terms of when they happened illuminates current seismic action and clustering as can be seen in the screenshot below. All in all, I believe this is an excellent visual tool to be appreciated by anyone who has even a vague regard for global geological hazards. The link to the home page is below and I strongly advocate having a glance.
In the face of climate change, it is the high latitudes that are set to suffer the most. The effects of anthropogenic global warming will be greater, as will the potential for geological and geomorphological hazards due to loss of ice mass. In accordance with a previous post of mine, Greenland and Antarctica will suffer from the repercussions of isostatic rebound which in turn can trigger earthquakes and potentially tsunamigenic submarine landslides. Similarly, melting of ice has notably triggered a volcanic response in Iceland and Alaska. Stewart et al.(2000) discovered that a 1 km ice load has the potential to allow rebound of hundreds of metres with accompanying stresses equal to plate-driving forces. Even a minor temperature climb in high latitudes can instigate hazardous ice melt even on a small-scale due to its sensitivity to change. The figure below [taken from McGuire, 2010] summaries the notable high latitude ice sheets and mountainous regions that are particularly vulnerable to temperature increases as well as their likely associated hazards.
The concept of an ‘ice quake’ has been introduced as an additional threat to high latitude regions and has been affiliated with the break up of ice sheets in Greenland and West Antartica. Ekstrom et al. (2003) presents the way glaciers and ice streams can occasionally “lurch forward” with a force strong enough to let loose elastic waves. This is powerful enough to be detectable on seismometers across the world. The energy wielded by these glacial earthquakes in Greenland and West Antarctica can instigate markedly more forceful tsunamis than a submarine earthquake of an equal magnitude (Song, 2009)*. ‘Ice quakes’ have seasonal patterns and the rate of occurrence has doubled over the last five years. Such temporal trends signify the link to the hydrological cycle and show how the glacial environment is responding to anthropogenic climate change. McGuire (2010) has referenced how ‘ice quakes’ are likely to become a particular threat to high latitudes in the future, especially in Chile, New Zealand and Newfoundland (Canada).
*Song, T. 2009. Glacial earthquake tsunami - a consequence of climate change. In: Proceedings, 3rd Johnston-Lavis Colloquium: Climate forcing of Geological and Geomorphological Hazards, University College London (Abstract).
So far, I have failed to stress the incomparable value of using models to simulate and predict geospheric responses to climate. A study of particular importance is that of Grollimund and Zoback (2001) whose model was designed to explore the melting of the Laurentide ice sheet as a cause of intraplate seismicity in New Madrid. The Laurentide ice sheet was a prominent feature of the last ice age covering most of Canada and much of North America. At its peak it covered 5 million sq miles and has been a major influence on climate throughout the Quaternary. The map below shows the seismic zone - incorporating the background seismicity and the extent of Reelfoot Ridge.
Paleoliquefaction data have shown that the New Madrid seismic zone experienced three major earthquakes in 1811-12 which appeared to occur on a 200-900 yr cycle prior to the seventeenth century event. The paleo reconstructions contain evidence of severe liquefaction likely to have been caused by a magnitude 7.5 quake or greater. Considering the region does not sit above a plate boundary, a significant trigger must have been present. Accordingly, there have been several proposed theories seeking to explain this phenomenon: a stress concentration from the nearby rift valley (Grana & Richardson, 1996), locally elevated heat flow inducing strain in the lower crust/upper mantle (Liu & Zoback, 1997) and a weak subhorizontal fault above the rift pillow (Stuart et al., 1997). Nevertheless, these aforementioned hypotheses are unable to explain the sudden seismic upsurge during the Holocene.
The temporal match between the melting of the Laurentide ice sheet (between 19-8 ka) and the escalation of seismic activity prompted James and Bent (1994) to first suggest deglaciation as an alternative theory. Using simple ice-sheet geometry, they noticed that the loss of glacial cover could modify levels of strain several hundred kilometres away. In an attempt to further examine how the Laurentide ice sheet dynamics could have affected seismicity in New Mexico, Grollimun and Zoback (2001) created a three-dimensional finite element model to more accurately simulate lithospheric properties and interactions between large-scale tectonics, deglaciation and the geology.
The main findings of the study concluded that “the perturbation caused by ice loading is to suppress seismicity, whereas ice melting enhances seismic strain release”. The bending of the lithosphere under the weight of ice causes north-south stress beneath the New Madrid seismic zone. This bend generates a shortening of the lower lithosphere in a north-south direction, and an east-west extension. It is the deformation of the lower lithosphere that transmits stress to the upper crust and promotes brittle failure observed in the Holocene seismic record. Overall, the model used in this study has allowed Grollimun and Zoback to say with confidence that the melting Laurentide ice sheet was at least partly responsible for intraplate seismicity in 1811-12. They also conclude that rates of seismic strain in the anthropocene are likely to match high rates of the early Holocene and therefore warn of the high risk of anomalous seismic hazards in the future.
To this point, I have painted the picture that a verification of global warming’s effect on earthquakes and volcanoes would be unwelcome news. This does not apply to everyone: in particular the insurance companies who have already begun to put a price tag on natural catastrophes. Whilst politicians and scientists have not obtained sufficient evidence to blame tectonic plate disasters on global warming, this has not stopped the insurance industry pouncing on the latest money-making scheme.
This movement began in 2008 when a study by Ernst & Young coined global warming as “the greatest strategic risk currently facing the property/casualty insurance industry”. The acceptance that all natural disasters from hurricanes to tsunamis are ‘man-made’ has unleashed a plethora of litigants to take to court. 2011 has by far been the most costly year, with the cost of disasters surpassing previous years within the first six months. The majority of this expense came from the Japanese tsunami which was ultimately valued at $210 million. In an absurd statement about the 8.9 earthquake that devastated Japan, the EU’s Economic and Social Committee president said the following:
“The earthquake and tsunami will clearly have a severe impact on the economic and social activities of the regions. Some islands affected by climate change have been hit. Has not the time come to demonstrate on solidarity – not least solidarity in combating and adapting to climate change and global warming? Mother Nature has again given us a sign that this is what we need to do”
It is comments like this that give the public a false impression. In a way, it indoctrinates readers to the extent that pure fact are ignored; we can say with certainty that Japan sits atop a subduction zone and is therefore notoriously at risk of major quakes but this is not mentioned in the statement above. This ignorance is abused by big businesses who see global warming as a profitable tool to exploit.
It’s time to sidestep away from tectonically-driven hazards and examine the future implications of climate change on mountain environments. By investigating the Eastern European Alps, Keiler et al. (2010) have observed the increased frequency and magnitude of natural mountain hazards; namely rock falls, debris flows, landslides and avalanches. These aforesaid changes originate from the climatic impact on land-surface stability. As identified in the Alps, anthropogenic global warming has successfully been correlated with long term changes in high-alpine temperature, precipitation, glacier cover and permafrost.
Alpine systems and high relief areas suffer from being particularly sensitive to climate change due to:
High elevation snowcover causing feedbacks that amplify climatic impacts
Albedo
Heat budgets
Slope angle and aspect
Sediment availability
Slope moisture supply
Aside from regional changes and significant seasonal differences, temperature in the Alps since the nineteenth century has exhibited an increase that is twice as much as the global average (Vavrus, 2007). Estimates for future temperature change expect a further increase by an average of 0.3-0.5oC.
Monitoring of geomorphological hazards on the Alps has been ongoing for decades, amounting to a rich archive of incidences when climate forcing has directly impacted the region. The chronology of past events shows that products of slope instability can be attributed to a combination of both human activity and climate variability (Stoffel et al., 2008). Human activities – including land management – play a minor role in comparison to the force exerted by relentless climate change.
The emerging warm, dry winters can be effectively paralleled to the mass of glaciers in the Alps. The glaciers had been slowly advancing up until 1980, which saw a shift to full retreat. The melting of glaciers can be tied in with the loss of permafrost across the Alps’ extensive mountain range. This supportive layer is responsible for reinforcing the mountain’s structure and its absence has already been held liable for deadly rockfalls in Matterhorn, Switzerland and avalanches in Austria. In response to the mass rescue of 70 mountaineers in Matterhorn, the International Permafrost Association met to conclude that:
“…the ground temperature in the Alps around the Matterhorn has risen considerably over the past decade. The ice that holds mountain slopes and rock faces together is simply disappearing. At this rate, it will vanish completely – with profound consequences”.
In the last ten years, the Alps have given scientists a preview of what might be expected in the future – the 2003 heatwave and the 2005 flood are indicative of the extreme events that might shake alpine regions. However, so far the hazards have been concentrated at high altitude where the settlements and infrastructure is small scale. Unfortunately, this also means that public awareness is limited. The effects of global warming have recently begun to gain attention as a very serious threat to the flourishing tourist industry in alpine regions. Normally, global climate models (GCMs) provide valuable predictions on future climate change but high fluctuations due to regional differences mean downscaled results are often plagued with uncertainty (Reichler & Kim, 2008). Course spatial resolution within the models is ineffective when dealing with the variable climatological effects of the mountainous Alps. Models also fail to simulate climate feedbacks and the extent of permafrost that controls much of the crysopheric system. Thus, it is apparent that further research is essential in order to understand these immensely complex mountain systems.
A: The Richter scale is not a physical device, but a mathematical formula. The magnitude of an earthquake is determined from the logarithm of the amplitude of waves recorded on a seismogram at a certain period.
The above is just one of the farcical myths dispelled by the USGS in its online earthquake FAQ section. Another is the slightly less absurd claim that nuclear explosions can cause earthquakes which herein leads to the subject of this blog post. Whilst amending the misconception over a Richter scale’s true form is relatively straightforward, the link between bombs and seismicity is far more controversial.
To begin with, evidence has been presented that the Afghanistan earthquake of March 2002 was ultimately triggered by the high levels of bombing that was happening simultaneously. Suspicions arise when one questions how the Indian and Pakastani test sites could have had an influence from a distance of roughly 1000 km away. A given explanation is that the thermonuclear explosion somehow generated seismic waves, which traversed toward the epicentral region in Afghanistan to shake underlying geology and trigger the earthquake. Estimations show that one of the largest nuclear tests produced seismic waves with an elastic yield of 40 kiltons. In comparison to the Earth’s semi-diurnal tides produced by the gravitational forces of the Moon and Sun, the elastic strain of this nuclear explosion was around 100 times smaller. It therefore seems nonsensical to assume that smaller nuclear tests could trigger an earthquake from 1000 km away. One would expect earthquakes of comparable size to yield enough elastic strain to set off a succession of seismic events. Since no triggering of this type has been observed elsewhere, it appears to have been a mere coincidence that the nuclear testing and the earthquake occurred in spatial and temporal proximity.
Equally, throughout the seismic record there has been no indication that earthquakes increase in frequency after an episode of bombing. This has not discouraged some authorities to make accusations that ignore the aforementioned evidence. For instance, after a fatal earthquake-induced landslide was set loose from the Huascaran Mountains in May 1970, the Peruvian government declared that it was the fault of the French’s atomic tests in Mururoa Atoll. The unconvincing allegation is ludicrous, since the explosions in questions occurred on the other side of the Pacific! At first glance it seems plausible to assume that the tremendous pounding of a nuclear explosion could stir the continental plates (especially at faults close to fracturing), however it appears that direct and instantaneous human attacks fail to penetrate the crust. Clearly, despite the force of such bombardment is not as powerful as the addition of gradually increasing and ceaseless strain.
The case studies and information I collected prior to writing this blog are found in more complete detail in: "Nuclear Explosions and Earthquake, the Parted Veil" (1986), Bruce A. Bolt, W. H. Freeman and Co., San Francisco.
I have recently come across a controversial article that has tested the validity of my previous appraisal relating the ability of melting ice caps to generate magma production deep below the earth’s crust. This new intelligence is in fact a direct response to the article that first sparked my interest in this topic.
The author of the retort, Steven Goddard credits that as stated in the original article, a direct relationship exists between melting point and pressure in magmas. Simply put – ‘as pressure increases, so does the melting point’. The phase diagram of basaltic magma below depicts this temperature/pressure link. Clearly, this shows that between 100 - 0 km depth, the melting point drops at least 300 oC (roughly 3oC/km). Since ice is close to one third as dense as basaltic magma, it can be assumed that a removal of 1 km of ice would reduce the melting point by around 1oC.
Goddard affixes as paper from the Carnegie Geophysical Institute, which produced an empirical measurement of the relationship for one basaltic mineral – diopiside. Where Tm is the melting point (oC) and P is the pressure (atmospheres) the following relationship was discovered:
Tm = 1391.5 + 0.01297 * P
With this, Goddard is able to calculate that since one atmosphere of pressure equals roughly 10 metres of ice – the melting point would be increased by about 0.0013oC with every additional metre of ice. Similarly, a loss of 100 metres would incur a decrease in melting point by one tenth of a degree. Interestingly, the peak thickness of Icelandic ice is only 500 metres, therefore a complete loss of the ice caps would cause an alteration in melting point by only around 0.5oC (Bourgeois et al., 1998).
Conclusively, it does not seem plausible that this tiny reduction in melting point could stir up volcanic activity at such depths to generate major eruptions. It is unlikely that glaciers melting could substantially modify the rate at which magma is produced, which ultimately controls when an eruption takes place. Finally, Goddard concludes that a depletion of ice coverage would minimise the creation of steam and ash (ash forms when magma is cooled and fractured by steam). It therefore seems sensible to assume that a loss of glaciers would change the nature of Icelandic eruptions. Without large steam/ash cloud emissions, volcanoes would behave more like those in Hawaii and potentially be less destructive.
For anyone who found the controversy surrounding fracking an enthralling topic, I have linked a BBC podcast from the One Planet series. This covers discussions from both sides of the debate and focuses on how the problem has manifested in New York.
But some alarmists in the media like to think it did. Reports have been published that point the blame to a combination of deforestation and hurricanes. The far-fetched claim is that the huge deforestation schemes ongoing in Haiti have left hillsides vulnerable to erosion. Geologist Shimon Wdowinski of the University of Miami argues that Haiti’s hillside degradation is enough to destabilise the earth’s crust. He says that the quake was instigated when a large volume of eroded land mass was shifted to the Leogane Delta from the mountainous epicentre. Perhaps this degree of mass movement could trigger local tremors but I’m hesitant to accept it could wield enough power to unleash such slaughter.
A more convincing reason behind the destructive magnitude 7.0 quake lies in the simple fact that Haiti sits atop a an active transform plate boundary – where the Caribbean plate meets the North American plate in a system known as the Enriquillo-Plantain Garden fault. Media scaremongers display the fact that Haiti has not had an earthquake in over 220 years as proof that modern day climate change must be the culprit. Since earthquakes in Haiti are rare but not unheard of, surely this is merely the return period of seismic events in this region? Is it not likely that after two centuries of built up lateral stress the fault was ready to release the strain?
Following on from my recent post that covered the effects of oil drilling operations, and after being prompted by Anson Mackay, I’d like to bring ‘fracking’ into the spotlight. Fracking – or hydraulic fracturing – is a method of extracting natural gas inside hard shale rocks. The process consists of drilling down to shatter underlying rocks and injecting into them a high-pressurised fluid (such as water, chemicals and also sand). This creates channels within the rock and enhances the extraction rate and complete recovery of fossil fuels (BBC, 2011).
The reason fracking is relevant here owes to the fact that there have been several small earth tremors recorded in the UK in the last year; and fracking is said to be the perpetrator. After a magnitude 1.5 and 2.2 earthquake struck Blackpool in spring 2011, the shale gas drilling operations where suspended until an investigation was completed. The outcome of this saw the accused energy firm Cuadrilla Resources admitting in a commissioned report that the quakes happened due to an “unusual combination of geology at the well site” and that it was “unlikely to occur again”. Needless to say, many were inclined to distrust the report and protestors from campaign group ‘Frack Off’ were reported to have climbed a drilling rig at Cuadrilla headquarters.
In a likely acceptance of their guilt, Cuadrilla terminated its shale gas drilling tests in June after a magnitude 2.3 tremor struck the Fylde coast in April and then reoccurred in May. This was recently reported by the BBC, which reiterated the ongoing clash between sceptical environmentalists and “hopelessly naïve” energy companies.
It is only relatively recently that hazard events have been recognised by the Intergovernmental Panel on Climate Change (IPCC) – a scientific body that strives to provide assessments on the state and risk of anthropogenic climate change. Within the organisation, Special Reports are drawn up on various topics, one of which particularly interests me – the Special Report on Extreme Events (SREX).
The proposal was first introduced by Norway during the 29th session of the Panel in Geneva, Switzerland in 2008. They had collaborated with the UN International Strategy for Disaster Reduction (ISDR) to prepare this report that focused on the risk management of extreme events. The IPCC were supportive and called for a revised edition to be presented to the Bureau at the 38th session in November 2008 for further consideration. From then on, the Working Group II have organised meetings, determined objectives and produced papers in preparation for discussion with the Panel in April 2009 on whether the project would be endorsed. The Working Group II have since piloted the movement in anticipation of the SREX approval session which took place very recently in Uganda on 14-17th November 2011. Yesterday it was reported that SREX was approved and accepted at this conference.
This project – whose complete title is the Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaption – is a beacon of success for scientists who have propelled hazard events into climate change discourse. For better detail into the report’s outline and contributors I suggest visiting this section of the IPCC website:
Yesterday, the summary for SREX was released which outlines the proposed procedures for policymakers when managing the risks and losses relating to future extreme events in conjunction with climate change. This report can be accessed via the link below:
So, having unintentionally focused on earthquakes, I would like to turn my attention to volcanoes. The way in which volcanism forces climate is well studied and documented to the extent that geoengineers have formulated a way to harness the cooling effect of an eruption in order to counteract the onset of global warming. For a better insight into the mechanisms that drive volcanism as a climate forcing factor and these proposed geoengineering schemes I would like to recommend a recent post written by my friend and fellow climate blogger Tom Hallam.
Nonetheless, there is little evidence circulating that climate change could reciprocally alter a volcano’s eruption schedule. The cardinal premise on which this is based comes from the logic that a thaw of global ice caps will remove a vast weight allowing magma from immense depths to be unleashed. Freysteinn Sigmundsson – a volcanologist at the University of Iceland – has stated:
“Global warming melts ice and this can influence magmatic systems… the end of the Ice Age 10,000 years ago coincided with a surge in volcanic activity in Iceland, because huge ice caps thinned and the land rose.” (World Climate Report, 2011)
One particular recent eruption made headlines worldwide… but not for its link to climate change. The eruption of Eyjafjallojokull in 2010 was famed for producing the mammoth ash cloud that grounded flights across Europe and spread animosity to millions (including myself, whose ticket to Miley Cyrus’ film premiere was rendered useless when the singer’s plane was unable to fly!) Scientists have struggled to link this huge eruption to climate change, saying that the glacier on which in sits was too small and light to influence local geology. Whilst theoretically, the reduction in Icelandic ice thus far has not been significant enough to trigger either a large eruption or a greater frequency of any magnitude events, Sigmundsson believes this will change in the coming decades (Sigmundsson et al., 2008).
His 2008 report showed that since 1890, 10% of Iceland’s biggest ice cap Vatnajokull has melted (Pagli & Sigmundsson, 2008). This has caused land to rise approximately 25 millimetres, consequently adjusting geological stresses. Rocks under an ice cap are at such high pressures that they are unable to expand enough to turn into liquid magma even if the temperature is high. The pressure decrease when ice melts therefore allows magma to form. Such results lead to the conclusion that an estimated 1.4 cubic km of magma had formed in response to the thaw. Ultimately, the study concludes that melting ice is the principal way in which climate change can have an impact on geology.
Here's a quick case of theatrical embellishment of climate change found in today's pop music. Don't take this the wrong way... I like the song, I like Miley Cyrus and I can't dispute the lyrics. So if plugging sly publicity into the everyday school run gets young people actively involved in climate change then this song has done its job!
I was very grateful to have had the chance to talk to the man who spearheaded the latest debate that climate change could govern the dynamics of the earth’s crust. I met Bill McGuire last week at UCL’s Hazard Research Centre to discuss his role in this debate and where it’s headed.
Having read a collection of Bill’s published articles in the field of volconology and other geophysical hazards, I was initially interested to discover how his research interests were broadened to integrate the geological consequences of climate change. He tells me that the process evolved naturally, beginning with the successful completion of his PhD that investigated the link between climate and the collapse of Mount Etna. Since then he says that “climate change is the greatest threat that the world has ever faced”, and therefore is a topic that anyone interested in the environment would be foolish to ignore. His stature at the pinnacle of his domain gives him opportunity to actively feature within the campaign to fight climate change, which he pursues out of concern for both the future and his family.
Admittedly, I had expected to leave the meeting resolutely swayed that the earth was prepped and ready to bring about colossal devastation at the hands of human ignorance. As it turns out, I learnt from Bill that scientists have received not one obvious signal globally that geological hazards are increasing in recent ‘anthropocene’ years, and it doesn’t surprise them! The debate that human-induced climate change will cause an increase in these events is purely rooted from theory and chronicled evidence. By this, I mean the well-established concept that sea level changed historically in accordance with glacial/inter-glacial cycles – in our discussion, Bill cites how in the past seismic events in Alaska and Greenland can be correlated to massive ice sheet removal of up to 30-50 km.
A valuable point made by Bill that I had previously not come across in my research was that way in which sea level rise can stabilise faults. Having written in a former post about how the Japanese tsunami has been linked to climate change in the media, I now endeavour to rebuke that statement given this fresh insight. In actual fact, Bill illuminates how it is more plausible that a greater weight of water lying on a fault at a subduction zone would increase pressure therefore stability. This mechanism operates at coastal regions and would decrease the frequency of tsunamis, which supposedly proves the Japanese tsunami was not a man-made hazard. Danger is not completely averted as when one section of the fault is strengthened, the instability can move further along the fault. Whilst rising sea levels can suppress the ‘big ones’, more earthquakes can be pushed inland (normally where major cities are situated) and potentially cause greater damage. Similarly, an influx of sea water at laterally moving faults – such as the San Andrea fault – would effectively unclamp the fault reducing frictional force and allowing it to slide easier.
Finally, Bill proudly explains how he instigated this controversial topic with a series of workshops that lead to a wave of academic papers including his compilation of articles for the Royal Society. Much of the progress made in this realm of science can be directly attributed to Bill McGuire; he organised a conference in 2009 and is planning another one for next year. A testament to the success of his work is the first ever inclusion of an ‘Extreme Events Report’ in the upcoming IPCC report released on 18th November. Currently, Bill is reviewing the 5th assessment for 2013/14 with the hope that a similar coverage of extreme events will be in the contents.
Needless to say, my meeting with Bill was a pleasure and I would like to thank him for both an informative discussion and for his generosity.
I have established that the earth’s crust reacts to a redistribution of stresses along its geological faults. This is precisely how drilling and mining can incur man-made earthquakes. For example, a greater frequency of tremors was detected subsequent to the commencement of oil drilling operations in the North Sea.
Looking forward, we would like to have confidence that geothermal energy development will offer cheap, clean renewable power. This venture has been rocked by reports from scientists and locals that drilling for naturally occurring heat could generate bigger earthquakes. Since its advent in the 1970s, the gradual intensification of geothermal drilling due to improvements in technology have been held responsible for successions of minor earthquakes that were felt thereafter. A particularly insightful example is the now infamous case of Switzerland’s geothermal project in Basel. In 2006, this resulted in a 3.4 magnitude quake after drilling three miles (4.8 kilometres) into the earth’s crust. The aftermath was covered by an article in the New York Times, stating that tremors shook the town and the operation was ceased.
Despite prevailing earthquake fears plus the knowledge of the aforementioned failed project in Basel, American company AltaRock have the intent to drill two miles deep into the San Franciscan ground using a similar method. The site had been chosen in the hope of tapping into the natural geothermal vents (nicknamed The Geysers) which are located approximately 90 miles north of San Francisco, near a town called Anderson Springs. Whilst AltaRock founder Susan Petty has maintained that all large faults will given a wide berth, doubts of the safety and rationality of this project are palpable amongst locals and geologists. A concerning point to make is that within the seismic impact report filed by AltaRock, they dodged the fact that an earthquake had been the cause of the Basal programme’s collapse. Instead, the company allege that the trigger of the quake was not fully understood, in spite of expert seismologists and project officials pleading its guilt.
Geothermal energy has the potential to be a clean, renewable and reliable resource. However power companies have been limited to harnessing shallow steam beds, geysers and vents to prevent an earthquake risk (even though these projects can still induce very small tremors). Henceforward, tapping the heat from the earth’s core is the challenge faced by engineers. Certain advocates of geothermal energy believe the method adopted in Basel and by AltaRock [shown in the figure below] is the way forward. Obviously, greater earthquakes originate at greater depths so drilling to such a distance carries a perilous risk. Seismologists insist that currently there is still major gaps in the scientific knowledge that prevent us from predicting with any certainty what will or will not shake the ground.
I decided it was essential to affix some theoretical proof of cases where human activity has been accountable for causing geological hazards. To begin with, there are copious examples of how the construction of sizeable dams can be linked to seismic activity in recent years. For instance, the Great Quake of Sichuan in 2008 was responsible for the deaths of 80,000 people. However, many pass the blame onto the recently built Zipingpu dam, situated barely 5 kilometers from the epicenter. Dr V. P. Jauhari’s coinsReservoir-Induced Seismicity (RIS)as being “… related to the extra water pressure created in the micro-cracks and fissures in the ground under and near a reservoir. When the pressure of the water in the rocks increases, it acts to lubricate faults which are already under tectonic strain, but are prevented from slipping by the friction of the rock surfaces.”
In spite of inexorable research, scientists are yet to negotiate a homogenous explanation for RIS that would help model diverse geological regions or predict where the phenomenon could manifest. However the following characteristics; found in the‘International Rivers’ Factsheet;have been accepted:
The most important factor controlling RIS is the depth of water in the reservoir.
Volume of water is also a critical variable that can instigate earthquakes.
Additional factors include local geology and historic seismic stress patterns in the region.
The construction of reservoirs can shift increased earthquake risk to areas with previously low frequency seismic activity.
RIS cases show that the area within 10-15 kilometres of impounded reservoirs suffers an increased rate of activity.
RIS can be rapid - noticed following the initial filling stages of the reservoir.
Conversely the effect can be delayed until later in the life of the reservoir.
Some minor cases have struck during the filling process.
It is important to note that reservoirs themselves are unable to produce adequate seismic energy to induce an earthquake. Despite many case studies – Koyna, India (1967) and Xinfengjiang Dam, China (1962) – exhibiting evidence of a strong cause-effect relationship, this rarely occurs where the earth’s crust is not already at breaking point. Essentially, the reservoir can stir up an earthquake event, which would otherwise have bided its time for hundreds or thousands of years(Gupta, 2002).Unsurprisingly, the engineering community have been disinclined to accept the danger of RIS. Groups such as the International Commission on Large Dams have stubbornly insisted that RIS should only be regarded for reservoirs deeper than 100 meters.
Worryingly, many dams currently under construction or planning are to be located in the world’s most seismically active regions, an example being the Himalayas. This is why evidence suggests that the advancement in technology on a global scale could severely alter tectonic activity, potentially introducing an era of "techno-tonics". Major dam-building schemes are lined up for other seismic hotspots including Iran, Turkey, Patagonia, Mexico and Central America (see map below). In response to the Sichuan Quake, geological experts in southwest China have successfully appealed for the right to suspend approval of large dams in geologically unstable areas until the risk of RIS has been addressed(Kerr & Stone, 2009).
The idea of generating an increased frequency of high magnitude earthquakes is unnerving; optimistically however the simple truth is that there are no known faults capable of generating a “mega-quake”. Earthquake magnitude is determined by the length of the fault - plainly speaking, the longer the fault, the larger the earthquake. Therefore, whilst an earthquake of magnitude 10 or higher is theoretically possible, it is convincingly argued that it is very highly unlikely. This has not discouraged American film director John Lafia from concocting not just an earthquake disaster movie, but a disaster of an earthquake movie.
10.5 is a disaster film originally aired as a miniseries for NBC in 2004 which answers what would happen if the United States was devastated by a series of earthquakes increasing in severity with seismologists becoming alarmed as they anticipate the next will surpass all historical records by reaching 10.5 on the Richter scale. Perhaps the more startling is when the team of USGS scientists formulate a plan to detonate nuclear bombs within the fault with the delusive hope that the heat will weald the fault closed. Unsurprisingly, numerous reviews of this science fiction have questioned whether the comedy element was intentional.
Besides wanting to share the triviality of this film, the reason for its mention is that beneath the vast layer of melodrama, its cryptic purpose is to send a wake up call that the forces of nature will always triumph over human sovereignty. Regardless of whether a movie should be an educational experience or pure entertainment, basing the plot on the use of science and technology adds credibility so audiences can have an affected view of reality. This is particularly true of 10.5, which allows viewers to witness notorious American landmarks reduced to rubble, advocating several popular misconceptions about earthquakes that scientists seek to refute. Unrealistic scenes include parts of California breaking away from the land and become islands, holes appearing in the ground at random and a giant crevice chasing a moving train. For some less informed viewers, this form of escapism evokes curiosity over what is fact and what is fiction.
Whilst 10.5 is a nonsensical attempt to create a hard-hitting blockbuster, its message stems from the realisation that humans have a destructive influence of the planet. Although the film is purely fantastical take on anthropogenic geological hazards, I found it intriguing that filmmakers have inflated the threat with elaborate cinematics for the big screen. Thus far, the most intense earthquakes that have been attributed to humans have not exceeded magnitude 6. Ironically, whilst the human flair for using engineering to manipulate the Earth may be a cause of such catastrophic events, no degree of man made restraint could ever chain them up.
Tsunamis are highly destructive waves triggered by underwater disturbances such as earthquakes, volcanic eruptions and landslides and so far have been unfairly overlooked in my blog. The mechanism that triggers these events is simple – increasing or decreasing the load atop the Earth’s crust initiates stresses and strains. As previously explained, shifting volumes of water can act as a heavy enough mass to generate crustal rebound.
At the end of the last ice age, a monstrous underwater landslide named the Storegga slide erupted off the coast of Norway (Ataken and Ojeda, 2003). As a result, parts of Norway, Scotland and Iceland were inundated by the giant tsunami wave of 25 meters in height that hit after approximately 3200 cubic km of seabed was displaced at the continental shelf. Ice melt in Northern Europe is held responsible for causing a sequence of earthquakes that culminated in the immense landslide. Contemporary studies have uncovered that Storegga was one of many strong megaslides caused by glacio-isostatic rebound in the aftermath of ice ages (Bryn et al., 2002). Over the last 1.3 million years, the Storegga area has been a hotspot for sliding due to the dominance of glacial/inter-glacial cyclicity.
A more recent consequence of underwater sliding occurred in 1998 when a tsunami killed 2000 in Papua New Guinea. At the time, Papua New Guinea was experiencing an extreme drop in sea level due to the prevailing El Nino conditions (Hasegawa, 2010). This leads one to believe that if rising and falling sea level triggers more earthquakes in coastal areas, the frequency of underwater slides and tsunamis is sure to increase.
Supporters of the theory that anthropogenic climate change could trigger a greater number of earthquakes are likely to refer the long term record of earthquake events. I came across the graph below from a USGS ‘Earthquake Project’ which aims to analyse earthquake trends. The figure clearly shows that in recent years the number of all earthquakes has shot up.
However, a graph like this can be misleading. For one thing the scale merely spans a 30 year time frame dating back to the mid-1970s therefore is unsuitable for assessing long term trends. More importantly, this ascending pattern can be suitably associated with the launch of a global network of seismograph stations capable of discerning low intensity earthquakes. Such ground movement was undetectable up until 25 years ago. A solution is to include only the earthquakes reported to be magnitude 7 or above – all these events would have been detectable with fewer stations using less advanced technology. Nonetheless, it is difficult to ascertain how accurate the earthquake record is during the 19th century. There is likely to be some incomplete data, therefore data sets may underestimate the occurrence of earthquakes before 1901. I have found that it is important to consider that this field of science is riddled with uncertainties and that a long term hazard record must be scrutinised.
The data below comes from the USGS. The relatively long time ranges (38 years) summarise how earthquake activity since 1901 has been continuously increasing. Having excluded all low intensity events, the figures suggest that more major earthquakes are occurring now.
Is this upward trend enough to make us believe that nature has finally risen up to combat human domination? Too many scientists surmise that the data above is tangible evidence to prove that the trend will continue to climb. The effects that anthropogenic climate change has on the inner workings of the Earth are far from certain and past events must be interpreted with consideration. Unquestionably the statistics allude to the fact that we are in a period of increased tectonic activity, but without establishing the cause it is unclear whether this trend will be sustained.
In addition to the ways in which humans indirectly steer crustal dynamics through their adverse effect on climate, certain other anthropogenic activities must be considered. Namely mining, oil extraction and the building of dams, which are figureheads of anthropogenic mastery over the Earth’s natural resources. Previously my account had been exclusive to hydrospheric processes affecting predominantly oceanic fault lines. It is important to add that sizeable constructions can also alter the strain on tectonic plates and lubricate fractures enough to shake the ground.
Human-induced global warming is unmistakably having an effect on the Earth’s ice and oceans: the melting of Greenland’s glaciers and the alarming sea level rise is well documented by the IPCC. However, what goes on beneath our feet is far harder to testify to. This has not prevented Bill McGuire of our Hazard Research Department here at UCL, from presenting evidence that has had many convinced that geological activity is increasing in response to global climate change. He along with six other authors complied a Theme Issue on 'Climate forcing of geological and geomorphological hazards' for the Royal Society. The aim of this blog entry is to introduce the arguments that support the notion that anthropogenic climate change could bring about a greater frequency of natural hazards.
Firstly, it is important to consider the role of glaciers and ice sheets on the Earth’s crust. Roughly 10.4% of the Earth’s surface is glaciated (approx 6,000,000 square miles), which exerts a significant weight upon the crust beneath. Consequently, the burden is lifted when ice melts allowing the crust to rebound (at a relatively rapid rate by geological standards). In tectonically active zones, rebounding crust could significantly alter stresses impacting earthquake faults and volcanoes. The Icelandic ice sheet Eyjafjallajökull sits atop a swarm of volcanoes of which would be triggered to erupt as a repercussion to any ice melt causing the unloading effect (Wadsworth, 2010).
The destabilisation of faults does not just trigger volcanic eruptions. The alteration of geological dynamics by loading and unloading of active faults elicits a ground-rumbling retort from the crust. Supporting evidence from history points to the melting of the Scandinavian ice sheets during the last Ice Age that prompted a succession of huge submarine landslides and tsunamis (McGuire, 2010). Whilst this seems to support the aforementioned theory, the concept is lacking in sufficient understanding about the actual nature and scale of the threat.
The distribution of meltwater adds another dimension to the problem, which is worsened by the rise in ocean temperatures, which causes water to expand through a process known as thermal expansion. The amalgamation of water acts as an added load on coastal fault lines. Its weight bends the crust which induces tension in the upper crust and compression lower down – a process McGuire likens to bending a plank of wood. The power of these forces can become strong enough to ignite catastrophic backlash. The winterly eruptions of Pavlof volcano in Alaska have been attributed to seasonal sea level rise causing compressional forces to release magma accumulated below the volcano. A study by Guillas et al. (2010) has revealed a correlation that links contemporary variations in El Nino Southern Oscillation (ENSO) to the occurrence of earthquakes in the East Pacific Rise (EPR). The observed 95% confidence interval is attributed to reduced sea levels in the eastern Pacific prior to an El Nino event that induced increased seismicity. This example illuminates how slight imbalances in the atmosphere and hydrosphere can shift environmental conditions enough to illicit a response from the Earth's crust.
Bill McGuire’s work has been influential to this field of science; his findings are soon to be published in his upcoming book ‘Waking the Giant: How a changing climate triggers earthquakes, tsunamis and volcanoes’. I anticipate this publication will be a benchmark in this emerging domain that links earth science to twenty-first century climate change. The link to the book’s Amazon page is provided below for enthusiasts who wish to delve further into the academic work surrounding the subject.
As little as 30 years ago scientists were still puzzling over the effect humans had on the earth and what was in store for future generations. It was then not until 1990 that the first Intergovernmental Panel on Climate Change assessment was completed and certainty was expressed concerning the warming effect of CO2, methane, CFCs and nitrous oxide emissions. Needless to say, climate change science is rife with disputes and confusion. At first, populations struggled with accepting that their daily energy consumption could be dominating the climate system of our own planet Earth, causing global temperatures and sea level to gradually eclipse natural fluctuations.
But is it too much to ask the public to accept that now their actions are causing major changes in the Earth’s crustal properties that could result in an increased frequency of geological hazards? It seems like nothing in today’s environment is immune to climate change, but can this atmospheric force wield enough power to influence tectonics and seismicity beneath our carbon footprints? The reading I have done prior to starting this blog has illuminated that this field of climate science is considerably split by a large divergent boundary.
On one side are those who see the concept to be a mere fabrication by the so-called global warming alarmists who seek to plaster climate change propaganda over every global disaster. The recent suggestions that the Japanese tsunami and the Haiti quake could be linked to climate change have been met with laughter amongst climate sceptics. Up until now, climate change cannot be accused of causing any direct casualties; perhaps a reason why its threat is scorned by so many. Studies have shown that whilst public acceptance of climate change is high, many still lack concern over a problem that is ‘too distant’ to affect them. It is much harder however to come to terms with the fact that your actions have indirectly taken the lives of millions of victims on the other side of the globe.
“Earthquakes are called natural disasters for a reason – they are not caused by emissions of that deadly, poisonous, toxic, hateful gas known as carbon dioxide, the life-giving substance that humans exhale and plants breathe.”
Stereotypically, advocates of climate change have an inflating archive of exaggerated claims as Watson sarcastically alludes to. Whilst it is easy to disregard this theory as yet another apocalyptical manifestation, I implore you to examine the mounting scientific evidence that indicates that human induced geological hazards are not imaginary. Is it time to accept that hazards aren’t as natural as they used to be?
Currently my position within the debate is firmly central. Despite beginning initially unconvinced, my first plunge into the literature has unearthed several convincing studies, which I will address in my next post. Conclusively, this blogumentary will follow my exploration into this emerging environmental topic which I hope will be enjoyably pursued by budding climate scientists to those of you who are keen to know if the survival techniques learnt in the film 2012 will ever be put to use.
