Tag Archives: seismic risk

The Natures of a City

Although they are the most living areas of cities, often hidden from view on city maps are the ecosystems beyond built landscape or paved roads.  But do we fail to orient ourselves to the extent of urban environments in ways that compromise our demand for livable space, by relying on maps’ abbreviated conventions?  For doesn’t any server only foreground a selective level of local detail, in ways that we have created to increase our dominant focus on roads, paved spaces, and buildings, to the exclusion of the constricted habitat that remains on the edges or borders of built space?

What would it look like, asked the folks at Nature in the City, a San Francisco-based non-profit, to create a map that foregrounded the habitat that has managed to flourish–and even be nourished–within an urbanized space, and in so doing to orient readers to  a counter-map of the built city, which might foreground the spaces of habitat that the group has encouraged across San Francisco and that exists on its streets?  The new model of urban exploration in the map that is used in the header of this post is based less on navigating the urban space we know, than exploding the nature/urban dichotomy, and pointing us to the cites where nature has taken shape in the urban environment.

The result is a reorientation to the urban map.  A long and storied tradition of urban maps that celebrates the built environment as evidence of the city’s vital form:  but recent debates about the prospects for urban livability have returned attention to the vital pathways and streams of live that undergird the city’s space; and in the case of San Francisco, perched between bay and ocean, and lying on multiple migratory routes of air and sea, the confluence between urban and natural spaces are perhaps especially salient to be of the moment as we try to remap urban space less in terms of buildings or built structures,–but rather to foreground those empty areas of  light green unfortunately rendered in rather generic flat light green hues in Google Maps, or any of the other map servers we use to navigate the congested streets of urban space.  As we are enjoined to “navigate our world faster and easier with Google Maps,” and believe in our abilities to do so, we too often tend to forget–or not see–ways that might orient ourselves to our surroundings or indeed what other sites in the world we might do well to pay attention to.  If there is a danger that we are at risk of loosing sight of places of nature in our mental geography of urban space, the data rich nature of the map of wildlife habitat compiled by Nature in the City don’t dominate the viewer with data, as strongly as some maps do–



–but help us to reorient ourselves to the dense population of the urban space by an understory that supports a rich variety of habitats, on which we can re-map our place in the city, less to an abillty to navigate our relations to urban space on its streets, but learn how other taxa live in the city, and use its space, in order to appreciate how we can be the best custodians of their habitat.  Indeed, the remove of any grey space from the map’s surface and open face–


SF bay clear shot Nature in the City.png


The intention is to invite us into urban space through -a new set of coordinates, so to speak, and ask us to orient ourselves to urban space by an expanded and enriched sense of  its habitation.

As we confront pressing questions of livability and the future of the long rhapsodized city of San Francisco, can maps better attune us to the changes of its urban space?  Perhaps the notion of how maps work to “civilize a space” and prepare it for our eyes has changed–or is trying to change.  The notion of cultivating and maintaining the order of a space seems better to respond to the exigencies and unknown future terrain that increasingly defined by global warming, climate change, sea-level rise, and a loss of species.  The sense of what such a civilization would portend–or how the space might be civilized–has been called into question as the role of manmade change in the environment has been questions, and maps struggle to wrestle with and process that change, taking stock of eventual effects of over-building, shifting shorelines, and planetary warming on where we–and not only we–live.  The problem of detaching the urban grid from the environment surrounding is addressed both by the image of San Francisco within migratory routes of birds, ocean mammals, and fish, and a living habitat for animal and plant life, and the increased awareness of dangers of overbuilding in a city framed by faults.

Given the complexity of the biosphere in an era when Presidential candidates proclaim their opposition to scientific consensus on climate change or Darwin’s evolutionary theory, the range of open data we have on the local biosphere provides a compelling way to place viewers in a complex ecosystem.  The value of open data to offer a range of yardsticks that can help ascertain the extent to which a bucolic city retains and map its relation to the natural world in the new map issued and designed by Nature in the City, a public interest environmental group whose work raises consciousness about urban greenspace.  While their map is not dependent on data alone, the map’s valuable text reorients us not to its streets, parks, or plazas, or its transit system, but instead to the levels of green cover in each neighborhood and the sort of ecosystems they afford–providing a new way to understand and explore its neighborhoods.

In contrast, a distinct view of natural forces and a quite contemporary sense of environmental vulnerability has been displaced onto the vulnerability of the recent spate of vertical building in the uncertain terrain of the liquefaction zone of San Francisco, in a recent visualization of the city’s downtown, within the new USGS maps of the shaky geological terrain of landfill on which much o the city is also built–and the questionable basis that sandy grounds to support ambitious skyscrapers in a city that has long lain close to the ground, unlike other metropoles.   Despite the risks of steel-frame buildings, the vulnerability of whose welded joints to seismic quakes may lead them to be inventoried as public risks  by the California State Legislature, the spate of skyscrapers in the past decade cast a shadow over an iconography of urban hope, journalist Thomas Fuller has shown in brilliantly illustrated articles for the New York Times.  Fuller’s outsider’s view of the instability of the city–and the limited safety that it allows to workers in the densely populated downtown, suggests the fears of fracturing of steel-frame condominiums and office buildings or paralysis of water-systems and electrical in upper stories of recent high-rises.  The fear was shown in a powerfully monitory map that suggests an alienation from of builders from the inland Hayward Fault or San Andreas fault lines, and set off alarms to anyone who read the article whose rapid online shares reflect its visceral conjuring of the arrival of the Big One much more concretely than earlier maps of the city’s sizable liquefaction zones.

Seismic Trap?





The disconnect between man-made and natural structures have almost been inverted by the energetic environmentalist activists who run “Nature in the City,” a local non-profit long attentive to the city’s open space–that seeks to direct our attention to the natural wealth above ground that make the city so livable.  The 2018 map they’ve produced invites attention to the complexity of its ecosystem all too often overlooked in its built space, and a far more detailed local view of the abundance of natural wealth that they same city contains–and indeed, if one scrutinizes the map, abounds.  For over thirty years, Nature in the City has raised consciousness by mapping San Francisco’s preservation of parks; the recent version more fully foregrounds the nourishing of a range of habitats, from its bayshore to its urban space, in a broader ecosystem.  The result is a counter-cartography to the city as an ecosystem for cars, unpacking non-grey spaces of the map and questioning the clear divide between greenspace and greyspvce on the surface of our maps.



As if in counterpoint to the concentration of online map servers that orient readers to paved urban space, the map tracks the presence of living forms in the city and directs viewers to vital pathways or corridors.  If such habitat areas are difficult to discern for inhabitants, as Thoreau and Emerson would remind us, they are important to attend to, to resist the longstanding dominance of mapping the city as a built space in ways extremely important.  And as we shift attention from mapping a human imprint on the world to taking stock of what environmental demons that imprint indeed includes–global warming, heat islands, and impermeable landcover–and strive to look for other forms to celebrate by looking at the overlooked within the urban grid, profiting from the observations and efforts of naturalists to remake ecosystems in the city’s urban space–and using their work to ask us to re-orient ourselves to the city.

A reference to Thoreau seems particularly appropriate, as the non-profit has worked to create a reflection on the ethics of mapping urban space and reading maps.  The ethics of reading maps is particularly needed today, and the sorts of deliberate and intensive reading that Thoreau championed–as well as attention to a range of natural forms–is demanded by the third edition of the paper map, whose text, content, and style were deliberated by a team over several years.  The non-human elements most often excluded from the built urban environment as transient and fleeting residents–trees, birds, animals, and insects–consciously gained amazing  visibility by foregrounding habitats and tree cover, uncovering corridors that raise questions about the livability of urban space–even if we rarely attend to them.  Even if the map is printed, it encourages the intensive observation of the world that its degree of local detail, depictions of lost streams and watersheds, as well as the local density of trees, lakes, and islands of urban forest demand, looking further into neighborhoods like the Castro and Noe Valley, but also the Financial District, Chinatown or the Outer Sunset, in ways that reflect its density of local data–



–in order to command a far greater degree of attention than we are usually used to pay to paper maps, or indeed to the neighborhoods we work or live.


haight.pngSan Francisco, Greencover in Golden Gate Park, Haight Ashbury, Buena Vista Park



San Francisco, Financial District green cover, with past shoreline marked grey and offshore bathymetry



San Francisco, Greencover in Chinatown, North Beach, and Telegraph Hill, with old shoreline and bay


San Francisco, Distribution of Trees, Shrubs, and Grass in Outer Sunset


1.  The most pressing questions both maps pose of the future of the city may pale before the different views they present of the place of nature in the city–ad the arguments they make about urban space.  For in questioning the city as a built structure, Nature in the City  focusses readers’ attention on a complex of lived environments apart from built structures, from which residents benefit.  The exclusive focus on paved physical plant of cities in most mapping tools leave us guilty of treating the limited descriptive parameters of map servers as if they constituted urban reality.

And in this sense, the map has arrived at an opportune time to shift attention from the hulking monoliths which San Francisco residents get their minds around, that seem destined to proliferate across a new skyline, in ways Fuller has repeatedly wrestled even as it has emerged in architetural renderings idealized for future buyers–


Future Skyline?.png


–as a real estate fantasy, dangerously out of touch with actual seismic risks.  And by inviting structural engineers to question the ethics of seismic responses in building codes, calling attention to their limited protection codes for urban residents in what is the most densely trafficked regions of the city, and most occupied by workers (if mostly white collar).  The interactive graphic of the appearance of such downtown mixed use buildings offered a chance to reflect on the effects of the 1906 earthquake and ask if such overbuilding inevitably suggested a sort of seismic trap.

The alarms that the built skyscrapers–without those planned–were cast clusters of danger signs in the scary prospective view of the city’s future ed buildings  of aassess the and an increasing debate over the final and future shape of urban space that invited readers to take stock of  an apparent rush to build on shaky grounds.

Seismic Trap?.pngfrom New York Times Interactive, April 17, 2018



The counter-cartography of the recent Nature in the City map offers a different lineage of mapping, shifting attention from the built structures to remind us that we risk filtering our actual experience of urban environments; for map servers, as much as lucre, also blind attention to an environment–or to spaces where we don’t drive–desensitizing ourselves to a delicate environmental balance, and masking the fluidity of habitats that cities include–the extent of open spaces in urban spaces that can nourish a broader ecosystem, even in a built space.  So much was revealed by increased attention to the embodiment of urban space in the recent map of San Francisco by the Nature in the City team, winner of a 2017 Livable Cities Livability award, that devoted increasing attention to finding and describing the parameters and metrics for the livability of a future urban space.  The emphasis on the encouragement of local habitats of native regional species in the city–and their dependence on the availability of water sources and green space–suggest a very different emphasis on the future of urban growth.

The future of urban space is surely rooted in its ability to be accommodate lived spaces that encourage habitat in the Nature in the City map.  By tracking local species, the distinctive nature of the city as an active ecosystem suggest a degree of civilization that respects the quite distinctive natural character of its terrain.  In ways as magical as movies as The Parrots of Telegraph Hill tracked the survival of a flock of exotic birds recently counted at three hundred, the map invites viewers to attend not to escaped pets or urban residents as raccoons, pigeons, or feral cats,



but the interwined tapestry of  ecosystems that map how San Francisco offers a complex space of “natural” habitats.  The inventive tools used to map its urban ecosystems incorporates a variety of mapping forms to remind us of deep currents in urban space, from the landfill or sandy grounds remaining under the downtown area to the unique habitat sandy beaches, green spaces, streets, urban forests, watersheds, and gardens, and recover a sense of its living corridors beyond what city parks allow.  The result is both a broad historical perspective on its living record, that allows readers to engage its situation in a broader ecosystem and as a habitat, but a new model for looking at cities and their livability.

The unique base-map serves to track living habitats across the city, using overlays to combine a variety of mapping forms usually seen in isolation. By employing LiDAR orthoimagery of trees, shrubs and grasses across the unpaved areas of San Francisco, as a guide to help us follow the habitats that the greening of a city allows, far beyond an exclusive focus on its parks as in earlier editions.  The revisionary nature of a base-map of urban vegetation help expose living habitats in the city by mapping forms, to show how the city as supports a diverse range of habitats we would rarely discover, but in which the living structures of the city might be best located and situated.  Even if we use our old mapping habits to approach the below map of greenspace in San Francisco–and try to locate where we stand, whose houses we’ve visited, or lived in, or where we remember meeting someone or had fun, as if to try to correlate that experience with the density of green cover, in exploring the actual map we try to “map” those greenspaces into the range of habitat that the city also preserves and includes.


LIdar Orthoimagery SFNature in the City basemap/LiDAR orthoimagery of San Francisco with added bathymetry


The density of the layers of open data that the map compressed–tracing the density of greenspace by its elevation and distribution, suggest an extremely sensitive register not only to situate but emplot animal and plant habitat in the city by the bay.   The availability of significant open datasets for San Francisco reveal an intersection between avian and mammalian taxa with its watery habitat so delicately to make one almost forget its place at the edge of the continental shelf, but to map its abundance.   The data rich nature of the map that almost is concealed in its pictorial elegance allows the readers to perform the sort of deep dive into localities that are foreign to most paper maps, indeed, and reflect the increasing skills of aggregating and distilling data in appealing visual forms, and indeed unpacking locality as a complexly variegated form.

The hope is to reorient ourselves to the city as a built environment, to think of it as a capacious space that makes room for the creatures that dwell around it–not urban animals, or foragers like raccoons, geese or pigeons, but historical dwellers of the land-sea continuum that San Francisco’s terrain was defined by, despite and notwithstanding the redefinition of the city as a space for building that was amplified by landfill.  The playwright Tony Kushner evoked the city as a bucolic terrain of a promised land during the mid-1980s in Angels in America—the “undulating landscape lying under the threat of seismic risk,” where danger only lay only in unexpected underground faults.  The conceit God abandoned the world left stage after the 1906 earthquake, due to the changes in human settlement of the globe, is almost returned to in the orchestration of a vast range of data on habitats and tree cover by folks at Nature in the City to create a map able that seems take stock of the deep patterns of urban environments still suggest its closest points of contact with the the divine.  Indeed, the deep reading of the terrain that the Nature in the City cartographer offers to situate the intersection of nature with its urban infrastructure provides a new model to examine the presence of nature in the built world.


2.  For while we are long trained to imagine as architectural landscapes as triumphal achievements, after the conceit of elevated prospective views that magnify the city as human achievement of God-like form–


Jacopo_de'_Barbari_-_Plan_of_Venice_-_WGA01270Jacobo de Barbari, Venetie MD (engraved woodcut perspective map of Venice, 1500)


–we risk perpetuating the urban myth of a space isolated from nature that erase the discovery that the living detail of urban habitats as something of the divine.  And in an age where the from of cities stands to change with global warming and sea-level rise, it’s incumbent to engage and re-examine the city as an environment, for in considering how the city functions as a habitat, less as detached from the world, we can help revise the mythology of the city as separated from the country, or from the variety of creatures, plants, and bugs that contribute to its livability.  And in an era when what a Secretary of the Environment should dedicate attention is still unclear, mapping an urban space that doesn’t account for the flows, currents, and fluid sense of urban space rooted in nature is unconscionable.  If pixelation can dissolve the harmony of the Barbari view,




the detail of the dive into the natural environment in the NITC map provides an opportunity to explore what exists outside, within and beside its built environment.  The availability of rich open datasets possessed by a city as San Francisco provide a counterpoint, allowing the foregrounding of deeper measures of urban change:  mapping such data can better help to embody urban space less reliant on the building blocks of squares, freeways, or paved space, but reveal an intersection of geography with native or indigenous habitat once again encouraged to develop.  Data maps can offer the opportunity and challenge to re-read the city and even to examine areas that foster wildness–and a range of indigenous wildlife–across beaches, urban forests, hills, and in its gardens, beyond parks.  A range of new visualizations of urban space reveal the new ways cities intersect with “natural” space.

The Nature in the City folks have shifted attention toward the many open spaces and gardens in the city, suggesting the forms of vitality San Francisco conserves, despite the challenges of many native inhabitants–from spotted owls to shorebirds like once-threatened snowy plover and the loss of redwoods, by focussing on the species in the city and the Western United States’ largest estuary.  Their map reminds us that as well as being a flyover spot for birds and shorebirds, San Francisco’s Bay is not the only  biodiversity hotspot for large numbers of endangered shorebirds; for the city’s open spaces provide crucial habitat that provides a model at a time of species die-offs and habitat loss–making the map a positive counter-model to such deeply disturbing trends.

Indeed, the city whose living currents they map apart from human life tell a far more positive story than the disappearance of regional watershed whose tidal marsh-lands have contracted by some 90% from 1800 to 2009, as the addition of landfill and diking transformed tidal marsh nineteen times the size of the current San Francisco by nine tenths, leaving much of its former vasst extent in the San Francisco Bay rather than the rich ecology of the delta.


90% decrease of of Bay Area Tidal Marshland, 1850-2009/California Wetlands


The ability to embody a range of open data can foreground and call visual attention to notice the huge diachronic changes in the local environment, or to focus on overlooked living aspects of the current city.


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Filed under data visualization, environmental geography, map design, San Francisco, San Francisco Bay

Mapping Fault-Lines in Earthquake Maps

Fracking–it is increasingly feared–invites irreparably contaminating our largest aquifers, and by extension drinking supplies–in Brooklyn, someone formed a group to protect the water of locally sourced beers–as well as devastate prairies and old agricultural lands, where land is cheap, by horizontal drilling.  Recent arguments compellingly link the drilling multiple “injection wells” of wastewater that seem to have activated previously non-active faults in regions that rarely experienced tremors in the past, and where the USGS did not find evidence of registered earthquakes.

As massive amounts of wastewater generated to access for natural gasses are forcefully re-injected into the earth, as if swept under a carpet, opening fissures in underlying beds of Shale or Sandstone.  Horizontal drilling operations have dated to 2008, mining areas by pumping vast amounts of sand into ancient shale formations in prairies and regions of declining agriculture to release methane and natural gasses.  Hydraulic fracking has used tons of water to force trapped gasses out of old rock formations.  Before 2009, in fact, earthquakes were rarely registered in the USGS surveys of lands where seismic activity has accompanied the injection of water into “injection wells”:  in these the shifting weight that the injected water that presses against rocks open old fissures, causing a buckling of underground rock formations, the fear is, as massive amounts of soupy, contaminated wastewater is injected back into the earth.  The “earthquake swarms” monitored nearby injection wells in Arkansas, Montana, Texas, Ohio or Oklahoma that barely registered seismic activity  from 1972 – 2008, has given new significance to–and created new fear around–a set of fault lines unknown to inhabitants, blamed as if active by an industry that rejects the accusations that they created sources for tremors inhabitants fear.   Indeed, the proliferation of earthquakes registered in the state of Oklahoma alone from 2001-15 reveals, according to the data from the Leonard Geophysical Observatory, a persistent increase in the tremor-like disturbances with the rise of underground wastewater dispersal, and a strikingly sharp increase in quakes of magnitude of three or higher in hears after 2010.


QUakes in OK, 2001-15.png


The increase seems closely tied to the absorption of wastewater back into rock layers whose weight is so altered by the injection of fluids, causing quakes that have rocked up to a fifth of the state, but have also increased land values for speculative fracking, in ways that may have concealed some interest in exploring the correlation–especially in a state where, due to geomorphological accident, water injected to reach deep-lying shale deposits send increasing amounts of wastewater underground, often to be absorbed by highly porous limestone that expands, but lies deep underground beside highly stressed layers of rock.  The result seems to create something like a combustive effect akin to the popping of kernels of corn, and has led many state officials to preemptively adopt prohibitions on local bans on regulating oil or gas wells in their jurisdictions, and insistence that the resurgence of quakes in fault zones is more able to be explained as an “act of nature that is nobody’s fault” not effected by human agency; the rejection of a relation to human activity comes from state legislatures fearful of the employment rises brought by gas and oil corporations from being scared away from the state.    But the geological record of apparently induced quakes in Oklahoma and their close proximity to existing injection wells.



The fear of such tremors has a recent prehistory of three or so years.  An early tremor whose epicenter lay near Richmond, Virginia, of 5.8 magnitude, just below 6, but that sent shocks to North Carolina and Canada.  The event raised questions about the role of fracking in 2011 for Tim McDonnell and Aaron Ross, described in an earlier article in Mother Jones that directed attention to fracking’s consequences.  But the persuasive nature of recent USGS time-lapse maps of the same state–

The dangers of fracking echoes Jonathan Franzen’s early if compelling 1992 novel Strong Motion, in which mysteriously recurring earthquakes are pinpointed at the unlikely site of Boston, Massachusetts, a rare location of seismic activity.  But whereas Franzen’s protagonist, Renée Seitcheck, believed “that these earthquakes are the byproduct of industrial drilling” by a  petrochemical firm whose agents attempt to assassinate a beautiful rebel seismologist, for her mining of top-secret data from computers, the causes of the “swarms” seem to lie less in drilling than in injecting waste-water.  Was the novel remarkably prescient in unveiling a concealed impact of post-industrial geocaching?  It surely doesn’t seem so paranoid in its view of an industrial conspiracy to conceal geological findings, or to imagine the role of the rogue geographer in the seismically sensitive landscape that the search for underground sources of oil and gas can create.

But now it’s no longer isolated individuals who research the papers of top-secret labs.  There are upwards of 40,000 disposal wells actually active in the United States, some tunneling 13,000 feet under the earth, and “injection induced seismicity” is now a field, as the pressure exerted by the displacement of water able to move rock layers has provoked widespread academic interest and industrial concern:  “There are faults most everywhere,” noted Cliff Frohlich of the Institute for Geophysics at the University of Texas-Austin, suggesting how fracking can ‘reactivate’ fault lines which were never known; “Most of them are stuck, because rock on rock is pretty sticky.  But if you pump a fluid in there to reduce the friction, they can slip.”  “Water does not like to be squeezed,” Scott Ausbrooks of the Arkansas Geological Survey put it with some empathy.   And while Franzen’s character pored over reams of secret data to understand the relations of seismic activity to big oil’s search for underground pools of oil, such relations are now the focus of conferences and are amply documented in data maps.

The best known faults the USGS has mapped are well-known.  But, as Mark Zoback, a professor of geophysics at Stanford explained in a recent article by Michael Behar in Mother Jones, echoing Frohlich, “there are faults everywhere, and some are too small to be seen.”  Faults are widely known if often forgotten by those living in California, where fracking may begin, despite growing opposition.  Indeed the range of fault-lines throughout the California-Nevada region are so multiple that the possibility of hydraulic fracking in the region of southern California threatens to  imbalance a rather threatening constellation of seismic activity that already exists in much of the region, and is more widely mapped than the most familiar lines of the San Andreas, Calaveras, or Hayward faults.  The visibility of these fault-lines is available on an up-to-the-minute-map of regional seismic activity, part of a set of maps that record seismic activity by irregular bright red computer-generated lines, often proximate to cities:

California in USGS map of Faultlines

The nervously drawn red lines of seismic activity furrowing the green plains in these maps are ‘underground views’ mapping the range of pressure below the earth’s surface.  A more striking map of seismic activity of the past few weeks and days pieces together a narrative of fault-lines and tectonic plates that accentuate the daily deep divisions that course under the earth of our westernmost states:


The stark legend suggests the huge growth in a magnitude the scale of “6.”  The prominent indexing of fault-lines in another USGS map of seismic activity, with less attention to topographic or climactic variation, shows the volatility of the region’s multiple faults in a similar if starker image of seismic frequency:



More locally, and limited to faults active in the past week of a magnitude above 2.5,
California in USGS map of Faultlines


For more focus on recent seismic occurrence, link your browser to: http://earthquake.usgs.gov/earthquakes/map/

Despite the evidence of terrifyingly active fault lines, the active movement ‘Stop Fracking in California‘ has its back against the wall, even if they are growing in local Southern California chapters.

Yet the volatility of the region cannot be ignored–take this map of the Simi Valley and Los Angeles area, posted on Saturday, February 16, where fault-lines course unseen beneath the landscape, moving from inland to the coast at multiple points and through metropolitan Los Angeles:

Los Angeles earthquake faults

This interest to frack in California–an oddly post-modern verb–is scariest given maps approximating the future likelihood, as calculated by the USGS, that the regional fault-lines in the Bay Area will experience seismic activity at a magnitude greater than 6.7 before 2036.


By how much would active injection wells multiply increase these already quite sizable odds?  Given the proximity of these lines to expanding urban areas, often growing between the Hayward and San Andreas fault, can fracking in California be a safe investment for the future?

This is not a map that is in the heads of most native Californians or residents.  The readability of these maps offers a base-line for future seismic activity, and grounds for concern about hydraulic fracking in seismically active regions.

It is good news that the USGS has expanded its clickable interactive image of global fault lines, in which the record of seismic activity is updated every minute, and on which viewers can scale in to investigate on their own:

USGS Global Earthquake Map

While the occurrence of faults and tremors will always shock, its legibility not only offers a lesson in continental drift.  Many of these jerky lines reminiscent of an etch-a-sketch lie underwater, but the points of greatest activity–in California, Indonesia, and Central America–cannot be ignored or lost sight of for underground engineers.


Filed under data visualizations, Earthquake Probability, Earthquake swarms, earthquakes, Fracking