Field photo Set #2

Late March - early April is the end of semester period, thus I'm swamped with term papers, labs, and presentations. I'm not one to procrastinate, since I've been burned by it in the past and learned my lesson. But activities like blogging must take a back seat, and I'm sure most reading this blog are experienced in what the last month of a semester is like.

So to keep things simple, for me and for you, but mostly for me, I have another pair of field photos to show, replete with explanation for the features' what/when/where/how. This time, a pair of volcanically-derived features in Oregon, both derived from eruptive activity from the legendary Mt. Mazama complex in what is today Crater Lake National Park.

The Pinnacles fumarole features, looking west.
The V-shape valley shows river erosion exposing them

To the right is a snapshot of the elegant Pinnacles, located just a couple of kilometers to the east of Crater Lake. These spires were ancient fumarole conduits of Mazama's gaseous content (SO₂, CO₂, H₂S), exposed by fluvial erosion from a radial stream, but remaining resistant to that erosive force. Prior to the finale of Mazama's VEI 7 eruption 7.7 Ka ago, a nuée ardente flowed down Mazama's east flank, carrying scoria. Gasses escaped from the settling scoria through fumarole vents, and the mineral content, given the extreme heat, welded loose pumice to the sides of the fumaroles. Thus the pinnacles seen to the right are hollow, and are resistant to erosion from the inside-out, which is atypical of common geologic thought.

When viewing the pinnacles along the 2-3 km path (42° 51.056'N 122° 0.558'W), I noticed that some of the spires had puncture holes in them, in which I could see through. The keen eye will also notice that the base the pinnacles stand on is a lighter color, which is due to the more silica-rich rhyodacite ash falls that preceeded the scoria-laden pyroclastic flow.

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This field photo is of a roadcut along the North Umpqua highway, not far from Watson Falls (43° 14.553'N 122° 21.486'W). Catching this roadcut out of the corner of my eye made me glad my car has a low center of gravity. This hillface, ~35km from Crater Lake, showcases silica-rich ashfall from Mazama during its major eruptive phase 7.7 Ka ago. The several-meters thick deposit is a testament to the volume of tephra ejected by the monster eruption (~60 km³), and its coverage across the northwest is found much further afield as well (Mount Baker slopes have a few cm thick of Mazama ash deposit, and it's over 600km from Crater Lake). Tephrochronology analyzes in the region are easily guided by Mazama ash, as the distribution of the ash from the centroid is quite ideal, making it a prime stratigraphic marker for 7.7 Ka.

The white color stems from sanidine feldspar content within the silica-rich ash, and darker grey portions contain a greater percentage of ferromagnesian minerals. The grainsize is quite fine, looks & feels almost silty, with a gritty abrasiveness, but not too harsh and not as hard as sheer-faced plutonic rocks. You can jab this rockface and it feels somewhat padded.

Additional Info:

• Mount Mazama and Crater Lake: Growth and Destruction of a Cascade Volcano
• Cascades Volcano Observatory - Mazama Ash
• Ellen Morris Bishop - Hiking Oregon's Geology
• Journal of Volcanology and Geothermal Research - Eruptive history of Mount Mazama and Crater Lake Caldera, Cascade Range, U.S.A.
• Charles Mandeville et al - Stable isotope and petrologic evidence for open-system degassing during the climactic and pre-climactic eruptions of Mt. Mazama, Crater Lake, Oregon

A glance at Saskatchewan Potash mining

Saskatchewan might not at first seem like a province that can build itself up as a preeminent world-class supplier of any resource. The population is only 1 million, spread out over a large area, and the climate has inhospitable extremes in the summer and winter. Yet Saskatchewan has built itself up as a leading supplier of a rare-earth salt called potash. Potash is essentially a water-soluble potassium-rich mineral that is often combined with chloride or carbonate, and it has coalesced in abundance underneath the sedimentary platform that defines the geology of Saskatchewan's prairie-lands. The industrial heart of the province has utilized this abundance to strike at rich in a world market where potash is an excellent & cost effective fertilizer for crops, and markets in India, China and Brazil have made it lucrative for the monopoly that Potash Corp. has created.

Why is Saskatchewan so rich in potash? 

That question can be answered by looking at the historical geology of the province. During the Devonian period 390 million years ago, southern Saskatchewan was inundated by a restricted inland sea. The equator was also located close to the province, thus the conditions were ripe for evaporation of water in the ancient sea, and thus the leftover mineral content collected and formed what are called evaporite beds. These beds were subsequently covered by later horizontal sedimentary deposits. The capping layers were not too thick, on the order of a thousand meters, thus drilling and mining access to the potash using modern techniques is cost & technically feasible.

World potash reserves, top ten states (left); cross-section of Saskatchewan strata with sylvinite beds (right)

Types and uses of Potash

Potash occurs when Potassium binds with another compound or element to produce a salt. Such compounds include Potassium Chloride (KCl), Potassium Sulphate (K₂SO₄), Potassium Carbonate (K₂CO₃), and Potassium nitrate (KNO₃), all of which have varying uses and grades of quality. Potash has general uses as a bleaching agent, a soap, and a de-icer, and technological uses in computer screens, but the majority industrial use of the compound is as a fertilizer of plant crops. The variations of potash mentioned above are all effective as fertilizers, because plants soak up the nutrients provided by potash when they are dispersed and allowed to percolate into the soil (after being soaked by irrigation). Potash's water-solubility allows this to occur effortlessly, and thus crops will soak up the nutrient content as they soak up water.

Not many countries produce and export commercial-grade potash, and Canada is by far #1 among the ones that do. Importers tend to be heavily populated countries that rely on extensive agriculture to feed their people.

Click to read more...

Earth Story: The Beeb's forgotten geology gem

I love it when I'm made aware of a documentary or TV miniseries about geology that I hadn't known existed, and I was just recently introduced to the BBC series called "Earth Story", an 8-parter released in the late 90's. A professor showed it in my historical geology class, using an old VHS tape of the program from the university archives. He used it to bring attention to such features as Banded Iron Formations and Stromatolites, and such events as the Rodinian Snowball Earth and ELE's. It's a perfect fit for a class on the evolution of the planet, and certain episodes would fit well in structural geology, geomorphology, paleontology, and geophysics classes, among others.

Naturally, I looked up the rest of the documentary on youtube, and lo and behold found a user's channel with virtually all of them available for ready consumption. I get easily addicted to geo-documentaries that are well presented, and Earth Story has an eloquent Englishman (zoologist Aubrey Manning), beautiful locations and brilliant animations, all prerequisites for a good doc. The series is well structured, with each part highlighting a piece of a particular whole of the history of Earth in geological terms, whilst building a story around revelations about certain phenomena. It has something for everyone, be you a geoscientist of one of the 4 major spheres, or an interdisciplinary. Without further ado, below is a sampling of the available episodes:


This part on Climate change examines Pleistocene glacial advances. Some of the interesting things you'll be informed about include coral reef terraces, foraminifera, smoothed tillite, Carbon cycle & the Carboniferous, Milankovitch cycles, and my favorite of using ice-core samples to reveal Pb atmo concentration during Roman times.


This part on Deep time discusses topics such as unconformities, geothermal gradient, ammonites, radioactivity's role in geochronology, pre-Earth meteorites, Archaean cratonic pillow basalts, lithified mud pools.


This part about volcanoes and the lithosphere examines mantle plumes, plate tectonics, seismic anisotropy, isostatic depression & rebound, mantle mineralogy, mantle convection, the Deccan Traps, Curie point.



This part on mountain formation looks into sea floor uplift, buoyant crust, slickensides, Gondwana's breakup, crustal thickening/thinning, geodesy, lithospheric flexure, serrate/entire leaf edges.

Above is just a small sample of the entire series. Thanks to Kurdistan Planetarium for supplying the videos online. Readers, enjoy!

Additional Info:

• University of Wisconsin @ Madison - Underneath the Mountains
• The Rules of Life - Welcome from Aubrey Manning
• Aubrey Manning discussion with Richard Dawkins

My day @ The Western Division of the Canadian Association of Geographers

On Saturday, March 12 I attended an interesting conference, the Western Division of the Canadian Association of Geographers, with plenty of excellent presentations that both faculty and grad students from a multitude of BC universities. There were plenty of interesting topical presentations to choose from, and with only an 8 hour stretch to fit in nearly 80 presentations, I had to choose 1 out of a possible 6 for every 20 minute time slot. Thus I'm having to send a lot of follow-up emails to those presenters I missed but wanted to hear their findings. One regret is that I wasn't able to catch much of the presentations on BC cordilleran glaciation, but luckily the lunch intermission allowed me to chat with some students on their findings and field experiences.

Figure showing hydrologic response in a coastal western hemlock
watershed. John Martin's investigations found that infiltration of
precipitation is excellent, as the nature of the soil allows for a high
hydraulic conductivity & porosity. Thus heavy rainfall doesn't result
in much overland flow, at least not until the subsurface reaches
saturation, and shallow depressions overtop.

I was able to catch presentations on GIS modeling of landslides, soil loss, and slope mapping of rugged terrain, in addition to my boss's talk on the decrease of agricultural land in Surrey, BC. He showed some maps I digitized, contrasting 30 years of shifting and merging agricultural lots and their tangible erosion in favor of RCI development. Most of the others I attended were on wetland hydrology and lotic ecosystems. The hydro presentations were quite technical in terms of highlighting their results, and quite advanced in terminology, but amazingly I found myself understanding most of what was said. That I attribute to my excellent Hydrology professor (who was one of the presenters), plus the presenters ability to define the important elements in their work. The only one that threw me for a loop was the aeolian physics of sand particles of a vegetated dune, and the subsequent quadrant mapping of their behavior during microclimate wind eddies & gusts.

Thanks to my university's geography department, the cost of the conference was covered, and I will direct the reimbursement to relief of the earthquake/tsunami disaster in Japan. Below is a list of the presentations I attended with, of course, my university profs in bold (gotta represent the alma mater):

• Connie Chapman (University of Victoria) - Turbulent airflow and sediment transport over a vegetated foredune, PEI National Park
• Parthiphan Krishnan (Kwantlen Polytechnic University) - A GIS for Municipally Enabled Sustainable Agriculture
• Terence Lai (Simon Fraser University) - Simulation of Urban Landslides: Cellular Automata approach
• Laurens Bakker (Simon Fraser University) - Spatial disaggregation of the Universal Soil Loss equation using Cellular Automata approach
• Brandon Heung (Simon Fraser University) - Automated procedure for digital landscape classification based on DEM data
• Sarah Howie (Simon Fraser University) - Vegetation variation across lagg forms of raised bogs in coastal BC 
• John Martin (Kwantlen Polytechnic University) - The Hydrologic response of a small forested swamp complex, North Vancouver BC
• Yue-Ching Cheng (Simon Fraser University) - Ins and Outs of Burns Bog: A look into the water balance of a large ombrotrophic bog in the Fraser Valley
• Jan Thompson (Kwantlen Polytechnic University) - Management of small water storages: A case study of small farm dams in New Zealand
• Steven Marsh et al (University of the Fraser Valley) - Variation of Fraser River, Kanaka Creek, and Silver Creek geochemistry
• Maureen Attard (Simon Fraser University) - Progress towards acoustic suspended sediment transport monitoring: Fraser River
• Jessica Craig (University of Victoria) - Dendroglaciological investigations at South More glacier, northern BC coast mountains

The study area in Jan Thompson's research into small farm dams in New Zealand (North Island). 39°58.218'S 176°19.850'E in Google Earth will place you around the highlighted watersheds, and by adjusting aspect you can see the drainage regime ultimately has its headwaters in the Ruahine Range foothills. Farmers with small dams (under 4m depth) gather their water mostly from first order streams, and Jan's investigations attempt to ascertain the cumulative effect these volumes will have on the larger whole downstream within the dendritic network, how they will alter the hydrology in regards to water quantity, water quality, downstream sediment transfer, and channel morphology.

I learned lots of new things, not only about technical terminology and equipment used in the field, but also on the sociopolitical state of the environment on scales small and large. With food prices increasing worldwide, food security is coming to the forefront as an increasingly acute issue. In regards to equipment I saw utilized by researchers, I had never heard of using a pharmaceutical device called a Wenglor sensor to count grains of sand, or a device called the ADCP (Acoustic Doppler Current Profiler); nor had I heard of certain equations, such as the Fernandez-Luque and van Beek equation. In essence, attending this conference has given me some extra homework to do, but that is all welcome cuisine for the cranium of this geo information junkie.

Additional Info:

• Western Division of the Canadian Association of Geographers 2011 Annual Meeting
• Burns Bog Conservation Society
• Cellular Automata
• Sedimentation Engineering google book

Field photo follow-up

This is a follow-up to the field photos I posted a month ago, and my best explanation of their origins and processes.

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First is a landform located in a gravel quarry in Squamish, BC (49° 43.899'N 123° 06.250'W). Access is via Sea-Sky highway #99. Take a right onto Mamquam Rd. near the Canadian Tire, and travel for 2km up to the quarry entrance, which will be on your left. The geomorphology of what you see below was created when the land in the area was much closer to sea level during the Pleistocene epoch. The environment of deposition was transitional, specifically a delta, represented by visible topsets & foresets. Bottomsets are presumably there, but have not been exposed by the quarrying. Since the region experienced glaciation during the Pleistocene, isostatic depression was the primary force for lowering the area to near sea level, and Holocene rebound has taken it up to its current 100m elevation. Evidence of glaciation is apparent from the mantle of glacial till, which overrode the underlying sedimentary structure during a later advance.

Second is an up-close shot of a granodiorite rockface that includes a granulite xenolith shaped somewhat like a tooth (49° 20.025'N 123° 07.124'W). The rockface is tremendously chemically weathered, turning it into saprolite. This chemical weathering mechanism is not indicative of the current mid-latitude temperate climate of BC, but is indicative of when BC was placed in a more equatorial latitude in its late Paleozoic-early Mesozoic paleogeography. The granodiorite is typical of so much of southwest BC, as it is a plutonic extension of the Coast Range batholith that encompasses the region, and by subsequent erosion has been thoroughly exposed. During its subduction-driven intrusion, the batholiths extensions baked overlying sedimentary & igneous units, and metamorphosed granulite 'polka-dots' became inclusions within much of the granodiorite seen at the surface. Touring Greater Vancouver, one can spot many instances of aggregate that uses the granodiorite w/ granulite xenoliths manufactured for construction and landscaping.

Access to this rockface: Follow Trans-Canada highway #1 west in North Vancouver. Take the Taylor Way exit and make a left turn onto Taylor Way. Head south for nearly a kilometer, and make a left onto Keith Rd. Follow Keith Rd all the way until you pass under the highway, then park and walk down a relatively steep trail to the Capilano riverside.

A couple more field photos will be posted soon, and this time explanations will be included forthwith. And just a small aside, a small rant: Anyone putting up paleogeographic maps on the web please, for the love of god, include major demarcations of latitude (equator, 30°, 60°, poles). It makes a world of difference in deducing paleoclimates.

Additional Info:

• Global Paleogeography
• Younger Dryas readvance in Squamish river valley, southern Coast mountains, British Columbia 
• Readvance of glaciers in the British Columbia Coast Mountains at the end of the last glaciation

Papers I'm reading: Declining sand dune activity in the southern Canadian prairies

"Visually, the dunes were incredible. They were at least four to five meters in height standing from the top, and there were about four-five rows of dunes. Most of them ran north-south in length. The wind picked up while we were there and I can understand how the dunes are moving so many mm's/cm's each year. The area surrounding the dunes was very desert-like (we spent one night nearby and I managed to get a cactus stuck in my foot, hurt very much). We could also hear the coyotes howl all night and in the morning witnessed several hawks flying by. The area was extremely dry, so much so that I even came across a sort of animal grave yard at the far north part of the main dunes. There was several skeletal remains of what I assumed to be cattle, though the bones were quite small and could have been deer. There were also plenty of little bugs wandering around the dunes, leaving their tracks in the sand, though I couldn't say what kind of bugs they were (although there were many "tiger bugs" I think that's what they are called)."

The above excerpt is courtesy of an aspiring journalist friend who has a keen instinct for the geographic/geologic, detailing an experience among some spectacular sand dunes: Writer's Fidelity

Her description of majestic dunes in southern Saskatchewan segues into the latest dozen-page intellectual nugget, coming courtesy of the Journal of Aeolian Research. The article is titled Declining sand dune activity in the southern Canadian prairies: Historical context, controls and ecosystem implications, authored by Chris Hugenholtz, Darren Bender, and Stephen Wolfe. The paper goes into detail about how the patchy sand dunes located in Southeast Alberta-Southwest Saskatchewan have been seeing a slow but steady decline for the past hundred years or so, and how this decline affects the ecosystem balance and the organisms that reside in the relict landforms:

Sandhills are islands of biodiversity in the southern Canadian prairies that sustain habitat for many rare and endangered species. These unique areas consist of large expanses of dune fields now mostly stabilized by grassland vegetation. Historically, the number of active dunes has decreased significantly due to vegetation stabilization, resulting in a dramatic decline of open-sand habitat for a variety of dune-dependent species. Without a certain level of wind erosion, opportunities for establishment of early-stage, species-rich vegetation types are diminished and open-sand habitat decreases by encroachment of the surrounding grassland vegetation. The current trend of dune stabilization, however, implies that wind erosion is decreasing, thereby threatening the continued existence of a variety of dune-dependent plants, arthropods and vertebrates, as well as other less-specialized species that benefit indirectly from these habitats. By reviewing factors contributing to the historical decline of active dunes, as well as the ecological implications of dune stabilization, the aim of this paper is to establish the biophysical context for new land management strategies that conserve valued landscape components, such as active dunes, and the processes therein. As dune stabilization continues management interventions will be required to sustain or re-establish open sand and the species that rely on these habitats.

Blowout dunes of Great Sand Hills, SW Saskatchewan

You can take a look in Google Earth @  50° 41.326'N 109° 17.069'W; most of the dunes are of the parabolic variety. The dunes are essentially relics from end of Pleistocene ice ages, notably the Wisconsonian, that have persisted due to a semi-arid precipitation regime and infrequent prolonged droughts typical of the prairies in SE Alberta/SW Saskatchewan. The southern prairies exhibit heavily glaciated terrain, wherein these glaciomarine-glaciodeltaic-glaciofluvial sands were derived from meltwaters at glacial fronts, and the region was subjected to katabatic winds flowing down off the front. The cold, sweeping winds were an excellent local atmospheric mechanism for sorting the sand into dunes.

The paper shows dune activity in 1900's declining due to dune stabilization via vegetation. Provincial action plans to reduce soil erosion has had a lateral effect upon the fragile ecosystem of the dunes and their plant & animal inhabitants. Thus in many ways, it is a "Damned if you do, Damned if you don't" issue, with anthropogenic activities being vastly responsible for currently affecting dune stabilization or proliferation. If left alone, the current climate change trend towards warming & disruption of precipitation regimes would likely lead to an increase in dune areal coverage, but only if decade-long droughts consistently occur. How does that work, though? If humans don't interfere with the dunes, our interference in the atmosphere will allow them to flourish?? In any case, the latter is already assured due to the lag of GHG's.

Ord's Kangaroo rat on sand hills

The real crux of the paper outlines what the implications are for the endemic flora & fauna. Since sand transport is effectively eliminated when vegetation cover exceeds 15%, the fragility of the dunes is acute due to the presence of rare, endangered species that habituate on blowout dunes. Within the paper there is listed over a dozen species of plants and animals in danger of extirpation. Examples include liverworts, arthropods, and the unique Ord's kangaroo rat. The latter is under threat due to dune stabilization allowing predators to corner the rats into an increasingly smaller territory with less space for effective burrowing. The dunes are stabilized by vegetation in a positive feedback mechanism that allows ruderal plants to proliferate on the dune perimeter by increasing surface roughness and changing soil properties to suite further veg expansion → if this goes too far, it will push out endangered dune-loving species like Ord's rat. The endemic animal plays a key role in the food web ecology of the southern prairies, extending an indirect influence outside the dune hills.

Co-operative efforts are underway in the prairies to allow some wind-driven erosion to facilitate natural dune migration & extent, though there is some back-forth wrangling with farm associations that prefer stabilization that protects soil resources. When looking at, for instance, the Great Sand Hills near Leader using Google Earth, you can see how farm lots completely surround the dunes. To conclude my observations, I generally get 3 things out of a peer-reviewed paper: 

1. A new term learned; in this case it was ruderal
2. A new question raised; in this case how does food security fit into the mix? If prairie farmers are wishing to avoid migrating dunes overtaking their lots, how do we address their concerns while allowing the dunes to flourish?
3. A new realization; in this case connecting elements to learn how glaciers can form picture-perfect dunes. I knew of katabatic winds, I knew that wind is the greatest terrestrial sorter, and that glaciofluvial is second greatest & capable of transporting & sorting fine sand. Integrate the mechanisms together to make the dunes?....I did not realize that til now.

Additional Info:

• Chart of Declining sand dune activity for various dune clusters (1925 - 2005)
• Government of Saskatchewan - Great Sand Hills Environmental Study
• Jessica Bell - Writer's Fidelity
• ISAR - International Society for Aeolian Research
• ScienceDirect - Declining sand dune activity in the southern Canadian prairies (Nov 2010)

Accretionary Wedge #31: "What the heck?!"

This will be my first contribution to the Accretionary Wedge blog carnival, and as a senior undergrad the topic suites me perfectly: What geological concept or idea did you hear about that you had no notion of before (and likely surprised you in some way)?

basic concept of gravity
when applied to rock density

Thanks to Jim Lehane of the Geology P.A.G.E. for hosting AW#31

For my first two years at uni, previously unknown concepts were a given on a weekly basis. But as my studies get more in-depth, the concepts are becoming more esoteric and/or specific. One concept from those early years comes strongly to mind, as it took me some time to grasp before the metaphoric light-bulb turned on: Gravity Anomalies

My physics teachers would drill it into us that acceleration due to gravity is a constant (@ 9.807 m/s²). GRAVITY, G,  IS A CONSTANT! ad nauseum. Then I was eventually presented with an alternate view of the consistency of the constant by my geophysics teacher. I, in my infinite lack of wisdom, and stubbornly sticking by what was told to me by my physics teachers, shirked off his silly idea of minute differences in gravity based on crustal thickness and rock types. I didn't really understand the mechanics of it the way he explained it, and it was never really tested on us students.

The true revelation came during a summer volunteer expedition with a local CGS glaciologist. As one of three heading up to the Matier Glacier within Joffre Lakes park, I got a taste of what experts do, and what instruments they use to analyze receding glaciers and the mountains they rest on. I found out that one such device we lugged up to the top, a microgravimeter, measures the gravitational field at a point. So the glaciologist operated it, got the reading in milligals, and I stood there dumbfounded. He was gracious enough to explain to me the concept of gravity anomalies...how it relates to crustal properties (such as thick, light mountain roots & thin, dense old oceanic trenches), and how we get the Bouguer anomaly, derived from measurements/corrections.

"Rocks have different densities, eg. felsic - ultramafic, and compression of the crust via plate tectonics can thicken the crust, developing structural mountains with or without igneous intrusions. These mountains have thick roots, sometimes 30+km from peak - basement. When such a thick mass is composed primarily of lighter granites, its lighter density is less of an attraction than when compared to a thinner, denser mass of heavier basalts. Denser basalts are found near subduction zones, especially above deep trenches. The phenomenon is comparable on continents as well: The Deccan Traps of Maharashtra measure a noticeable difference in gravity compared to the Himalaya ranges in Uttarakhand."

Upper Joffre lake. Behind would be the tongues of the Matier Glacier.
This is where I learned about gravity anomalies, luckily not by tumbling down to the tarn

Thus I was enlightened to a concept that had previously been muddled in my brain. I've even had a couple opportunities to apply it to my personal and work projects (ie. Cornwall geology post). It's become an increasingly seen concept in higher level textbooks I've perused, and more and more diagrams & cross sections that have caught my eye combine topographical profiles and Bouguer anomaly milligal values (example below).

Simple profile showing Bouguer anomaly values with general topography across the US

In retrospect, I wish I had a time machine, so I could go back and tell my junior undergrad self about how not to take anything for granted in the scientific studies. Geology always seems to smash preconceptions built up by the other science disciplines, and that's something I love about it. For anyone interested, Britain & Ireland geological survey's have done some extensive gravity surveying, and documented some interesting positive & negative zones. Check out the additional links for it.

Additional Info:

• Gravity Anomalies of Britain and Ireland
• Bouguer gravity anomaly for the contiguous US
• Various gravity anomalies mapped in the Canadian Arctic

Picking the best place to live, geologically speaking

I rarely get to have discussion with human geography students, but the natural hazards class I recently completed had a good spread of the physical geeks with the human geeks. One human friend mentioned how she lives in a neighborhood on the edge of a broad alluvial fan, and that her parents have little clue as to the potential dangers of living on such a precarious foundation protected only by modest dikes, which I might add have had increasingly shrinking freeboard values for the past two decades. The deflecting reason they gave her is that "developers would not have built here if it wasn't safe". 

Oh no, they would. Developers hedge their bets, and most in our regional district tend to downplay the importance of geophysical reports. Developers will push through proposals with hard cash to get the required zoning, especially if the 'view' and location is something that will bring them big bucks. This is not to say that they will cut corners wherever possible, as most of the time construction is top-notch, corresponding to strict standards for quake-proofing and packing down the sediment if the foundation happens to be laid upon Holocene alluvium.

Where is this post leading? Well, in my humble opinion prospective home owners have to take on some proactive responsibility themselves. Common sense dictates that the buyer beware, and there is no excuse for an educated westerner who does have the rights and the access to geophysical information to not take some time and look at it. Where I live in beautiful British Columbia, our own provincial division of the Canadian geological survey has done some excellent work on investigating factors that determine how damaging certain natural hazards are in certain areas. Below you'll notice fragments of a poster that outlines the traffic-light approach to categorizing hazards:

Slide hazard map of Greater Vancouver.
Light green circles indicate known slide occurrences

Liquefaction hazard map of Greater Vancouver.
Red zones mostly correspond to deltaic and alluvial deposits

Flood hazard map of Greater Vancouver.
The red zones are deltaic and alluvial plains, and have experienced little uplift
since the fill is mostly Holocene. The grey zones are Pleistocene glacial uplands,
mostly till, and benefit from tens of meters of thickness + isostatic rebound

Tsunami wake from Jan 26, 1700
megathrust quake. Ghost forests
attest to unbuckling of plates,
causing meters of subsidence

Looking at this one source of credible information already alleviates a lot of concerns a potential home owner would have, especially in our tectonically active region. Sure we haven't had a big one in living memory, but that doesn't mean we are out of any proverbial woods. On the contrary, the lack of moderate quake activity off the coast of Vancouver Island has led geophysicists to investigate and conclude that the Juan de Fuca plate & North America plate are locked at the shallow subduction contact, and tension is building to an inevitable unbuckling. Whether that results in one huge snap of a megathrust akin to the 1700 Cascadia quake, or a series of smaller unbuckling motions is yet to be seen.

I was asked if I chose where I live because it is among the safest spots in the region. I reside on the glacial uplands, on the crest of a street with a gentle slope. Alas, as a student with a limited budget and only part-time jobs, I cannot claim that I was so smart to have chosen such a safe spot. It's pure coincidence, I chose it because I could afford the rent. But I have dodged a bullet, so to speak, by digging for this knowledge and taking it to mind before I do make my first home purchase years from now. I've already compiled a short list of personal rules for where a home should be, to which additions will slowly be added:

• At least 300m from shore
• At least 50m asl
• Not adjacent to any slope greater than 25°
• Not on any faults, not even ones considered “inactive”
• Not on any META bedrock that has extreme foliation
• Not on any SED bedrock where bedding planes are poorly indurated
• Not within the boundaries of a 1 in 50 year floodplain
• Not within the boundaries of a 1 in 100 year floodplain if recent evidence has shown urban development has forced flow to concentrate, and thus freeboard values for dikes are consistently less than 2 feet
• Not on any foundation that has a layer that swells when saturated (ex. Bentonite)
• Observe wind direction patterns if living on or near a sandy desert or high altitude snowy area, to avoid home being buried by windblown material
• Not on any bedrock that has a lens of limestone beneath (GPR should discover it), lest it dissolves and a sinkhole forms
• Not within a radius of 300m from the edge of a forest prone to fires. Consider making the perimeter of your property fuel-free

I know a few of these are not economically feasible, but I've tried to arrange them in what I consider their order of importance, and the first several are free provided some time and effort and some light education. The GPR might not be an option, but if buying a $seven figure$ home, it's worth it for peace of mind. Above all else, look at the hazard history of the area you're moving into.

I'm not touching on atmospheric hazards, but they should be looked into as well. They're kind of a big deal too.

Additional Info:

• IRIS - Subduction Zone Plate Interaction
• USGS - The Orphan Tsunami of 1700
• GSC - GeoMap Vancouver