tag:theconversation.com,2011:/global/topics/geographic-information-systems-25493/articlesGeographic Information Systems – The Conversation2019-08-28T12:26:53Ztag:theconversation.com,2011:article/1222462019-08-28T12:26:53Z2019-08-28T12:26:53ZNorth Korea: how public execution sites are being mapped with Google Earth satellite images<p>As North Korea reignited international tensions in recent weeks with new rounds of <a href="https://www.nytimes.com/2019/08/23/world/asia/north-korea-missile-tests-japan-south-korea.html">missile tests</a>, the hope generated by the <a href="https://www.cfr.org/blog/singapore-summit-meeting-message">summits</a> between Donald Trump and Kim Jong Un has come into serious question. </p>
<p>Amid the ups and downs in the international community’s relationship with the North Korean regime, human rights activists have <a href="https://www.nknews.org/2019/02/how-to-engage-north-korea-on-human-rights-nk-news-podcast-ep-57/">sought to remind the world</a> that conditions remain grim for North Koreans.</p>
<p>For the past two decades, human rights organisations based in South Korea have worked with North Korean escapees to gather evidence on the <a href="https://www.ohchr.org/EN/HRBodies/HRC/CoIDPRK/Pages/CommissionInquiryonHRinDPRK.aspx">scale and nature</a> of the regime’s oppressive policies. </p>
<p>More recently, some organisations have begun <a href="https://en.tjwg.org/wp-content/uploads/2019/07/2019-Report-Mapping-the-Fate-of-the-Dead-Killings-and-Burials-in-North-Korea.pdf">applying</a> new technologies to <a href="http://www.hrnkinsider.org/2018/08/satellite-imagery-shows-captives-inside_30.html">complement</a> testimonies gathered through interviews. These include Geographic Information System (GIS) technology, which applies geographical analysis to detect patterns of state abuse not always apparent from interviews.</p>
<p>As the quality and availability of open source satellite imagery have increased, <a href="https://beyondparallel.csis.org/tag/satellite-imagery/">North Korea analysts</a> have uncovered new information about the secretive state. </p>
<h2>Executions and burials</h2>
<p>The <a href="https://en.tjwg.org/">Transitional Justice Working Group (TJWG)</a>, a non-governmental organisation based in Seoul, South Korea, which investigates deaths of North Korean citizens in state custody, recently <a href="https://en.tjwg.org/wp-content/uploads/2019/07/2019-Report-Mapping-the-Fate-of-the-Dead-Killings-and-Burials-in-North-Korea.pdf">reported on a long-term project</a> documenting North Korea’s human rights violations using GIS technology. Sarah was part of the small team of Korean and international researchers who wrote the report.</p>
<p>The project, which is ongoing, has so far gathered more than 300 reports of public execution sites – including hillsides, fields, markets and sports grounds. It has also gathered information on more than 25 sites where bodies have been disposed of by the state, by burial, cremation or other means. Public executions have been carried out for alleged offences including violent crime and watching illegally imported South Korean media. Yet the most commonly cited charges were related to property theft, such as stealing copper or livestock.</p>
<p>The researchers show North Korean escapees Google Earth satellite images of areas of the country where the escapees either lived or spent considerable periods of time. Focusing on images dating from around the time the reported events took place, where available, researchers then ask interviewees to point out the locations of any killing or body disposal sites of which they have knowledge.</p>
<p>These points are recorded along with the escapees’ narratives about the events associated with the sites, key details of which are put into a database. It then becomes possible to analyse the relationships of geographical coordinates to other variables, such as dates, associated criminal charges or proximity to certain government facilities. As the body of data grows, patterns in these relationships begin to emerge.</p>
<p>For example, the research shows that public executions have been clustered in many of the same spaces, such as a section of a city’s river bank, since the 1960s. The mountainous nature of North Korea, as well as the limited availability of fuel for transport suggests that officials from the Ministry of People’s Security may not travel far from a public execution ground to bury the dead and may reuse the same site repeatedly.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/289265/original/file-20190823-170935-18zaomj.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/289265/original/file-20190823-170935-18zaomj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/289265/original/file-20190823-170935-18zaomj.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=573&fit=crop&dpr=1 600w, https://images.theconversation.com/files/289265/original/file-20190823-170935-18zaomj.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=573&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/289265/original/file-20190823-170935-18zaomj.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=573&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/289265/original/file-20190823-170935-18zaomj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=720&fit=crop&dpr=1 754w, https://images.theconversation.com/files/289265/original/file-20190823-170935-18zaomj.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=720&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/289265/original/file-20190823-170935-18zaomj.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=720&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Data collected by putting together testimony from North Korean escapees with geographic location data.</span>
<span class="attribution"><a class="source" href="https://en.tjwg.org/mapping-project-north-korea/">Transitional Justice Working Group</a></span>
</figcaption>
</figure>
<p>This process presents some challenges, including working with memories affected by the length of time since the events occurred, or confusion between events due to the sheer scale of abuses which have taken place over many decades in North Korea. Determining when a certain mass public execution occurred, for example, may be difficult when the interviewee can only recall that it was sometime in the early 1990s, when the weather was hot. But locating where such events happened on a map, and looking at multiple accounts related to the same site, can help researchers uncover common trends in state-sanctioned killings.</p>
<h2>Building a case</h2>
<p>The use of these technologies has not been without its <a href="https://www.nknews.org/2018/12/whos-deceiving-whom-open-source-north-korea-imagery-under-the-microscope/">critics</a>, given the potential to <a href="https://theconversation.com/satellite-imagery-is-revolutionizing-the-world-but-should-we-always-trust-what-we-see-95201">misread the data</a>, even by experts. Still, the high barriers to entering the country make satellite images an important source for outside observers of North Korea.</p>
<p>The hope is that satellite analysis will help future efforts to investigate and preserve certain sites as crimes scenes. Information gathered now can help trained forensic investigators work together with GIS analysts to more accurately locate the remains of victims, or where other evidence related to state-sanctioned killings and burials may be located. If North Korea becomes more open, it can also provide an understanding of the environment surrounding particular sites ahead of time, such as ease of access and potential costs of investigation. </p>
<p>This work is not without risks. There is no way to know whether the North Korean state may tamper with sites if it knows they have been identified, as happened in places such as <a href="https://www.srebrenica.org.uk/what-happened/srebrenica-genocide/uncovering-mass-graves/">Bosnia</a>. As a result, for the time being, TJWG’s coordinates of sensitive sites such as killings and burials are not made public.</p>
<p>Any information gathered will need to be validated when access to North Korea becomes possible. There is always a risk of error because satellite images can <a href="https://theconversation.com/satellite-imagery-is-revolutionizing-the-world-but-should-we-always-trust-what-we-see-95201">vary in quality</a> and the available data on North Korean infrastructure is far from complete.</p>
<p>The regime is concerned about the world finding out about its state-sanctioned killings. North Korean escapees told the researchers that in 2013 and 2014 local police used hand-held metal detectors to find and confiscate all mobile phones from the assembled crowd prior to an execution, to prevent anyone from recording the proceedings. If photo or video evidence were to get out, it could be possible to cross-reference it with satellite data as <a href="https://www.bbc.co.uk/news/av/world-africa-45599973/cameroon-atrocity-finding-the-soldiers-who-killed-this-woman">the BBC has done</a> elsewhere, offering a more detailed picture of North Korea’s abuses to the international community.</p>
<p>Analysing data in <a href="http://greengeographer.com/gis-search-for-the-missing/">more advanced ways</a> can help human rights groups and the populations they serve get closer to the facts of abuses on the ground.</p><img src="https://counter.theconversation.com/content/122246/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sarah A. Son was employed by the Transitional Justice Working Group as part of the research team at the time this research was conducted and co-authored the project's latest report. She continues to support the project in a voluntary advisory capacity. The project was funded by the National Endowment for Democracy. </span></em></p><p class="fine-print"><em><span>Markus Bell does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>By matching narratives from North Korean escapees with Google Earth images, a fuller picture is emerging of abuses in North Korea.Sarah A. Son, Lecturer in Korean Studies, University of SheffieldMarkus Bell, Migration & Social Inclusion Researcher, University of SheffieldLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/808612017-08-03T01:00:21Z2017-08-03T01:00:21ZSoundscapes in the past: Adding a new dimension to our archaeological picture of ancient cultures<figure><img src="https://images.theconversation.com/files/180405/original/file-20170731-22169-j5elmn.JPG?ixlib=rb-1.1.0&rect=312%2C0%2C2759%2C1811&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">What sounds did the people of Chaco Canyon hear during daily life?</span> <span class="attribution"><span class="source">David E. Witt</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>Picture an archaeological site, what comes to mind? Sandstone walls, standing in the desert heat? Stonehenge, watching over a grassy field?</p>
<p>When thinking about archaeological sites, we tend to conceive of them as dead silent – empty ruins left by past cultures. But this isn’t how the people who lived in and used these sites would have experienced them. Residents would have heard others speaking and laughing, babies crying, people working, dogs barking and music such as drumming. These sounds could be heard from close by, and perhaps coming from distant locations as well. </p>
<p>Putting sound back into the archaeological landscape is an important part of understanding how people lived, what they valued, how they shaped their identities and experienced the world and their place in it. This growing field is called acoustic archaeology, or archaeoacoustics. By considering the sounds heard by people moving through the landscape, we’re able to more fully understand their culture, and thus better relate to them as human beings.</p>
<p>We <a href="https://doi.org/10.1016/j.jasrep.2017.05.044">recently modeled an ancient soundscape</a> at the landscape level for the first time. What can our ears tell us about the way the Anasazi, or Ancestral Puebloan, people lived in New Mexico’s Chaco Canyon more than a thousand years ago?</p>
<h2>Modeling ancient sound</h2>
<p><a href="https://uofupress.lib.utah.edu/chacos-northern-prodigies/">Chaco Canyon was the center</a> of <a href="https://sarweb.org/?sar_press_a_history_of_the_ancient_southwest">ancestral Puebloan civilization</a>. It’s famous for its great houses – large, multistoried structures, some the size of football fields – built and used from approximately A.D. 850-1150. Archaeologists have studied how the Ancestral Puebloans <a href="https://uofupress.lib.utah.edu/the-architecture-of-chaco-canyon-new-mexico/">built the structures of Chaco Canyon</a> and <a href="https://sarweb.org/?sar_press_chaco_experience">placed them in relation</a> to each other and <a href="http://www.solsticeproject.org">to astronomical alignments</a>.</p>
<p>To add a new dimension to our understanding of this time and place, we investigated how sounds were experienced at these sites. We wanted to know how a listener would have experienced a sound from a specific distance away from whatever was producing it.</p>
<p>To explore sound physics and its application to archaeology, we first developed an Excel spreadsheet. Our calculations described linear sound profiles, similar to a line-of-sight analysis; this took into account a straight path between the person or instrument making the noise and the person hearing it. However, this approach was limited because the results applied to only one listener standing at a very specific location a set distance away.</p>
<p>Our research truly blossomed when we wondered if we could apply the same sound physics calculations to an entire landscape simultaneously. We turned to a type of computer program called Geographic Information Systems (GIS) that allows us to model the world in three dimensions.</p>
<p>The software package we used, ESRI’s ArcGIS, offers anyone the option to create customized tools, such as the Soundshed Analysis Tool we created, to do calculations or create geographical data and images. The Soundshed Analysis Tool is derived from an <a href="http://www.acousticecology.org/docs/TWS_SPreAD_usersguide.pdf">earlier modeling script</a> “SPreAD-GIS” developed by environmental scientist Sarah Reed to measure the impact of noise on natural environments, such as national forests. That tool was itself adapted from SPreAD, or “the System for the Prediction of Acoustic Detectability,” a method the U.S. Forest Service devised in 1980 to <a href="https://www.cabdirect.org/cabdirect/abstract/19811878509">predict the impact of noise</a> on outdoor recreation. </p>
<p>The Soundshed Analysis Tool requires seven input variables, a study location and elevation data. Variables include the sound source height, frequency of the sound source, sound pressure level of the source, the measurement distance from the source, air temperature, relative humidity and the ambient sound pressure level of the study location. We gathered this information from a variety of sources: open-source elevation data, archaeological research, paleoclimatological research and historical climate data. We also gathered from the relevant literature the decibel levels of crowds, individuals and the conch trumpet instrument ancestral Puebloans used.</p>
<p>Once the input variables are entered, it takes the Soundshed tool less than 10 minutes to crunch through this complex math for every point on the landscape within two miles of the spot where the sound is produced. Our model then creates images that show where and how sound spreads across the landscape. This gives us a way to visualize the sounds people would have experienced as they moved through the landscape, going about their day. </p>
<h2>Who could hear what, where</h2>
<p>We focused on culturally relevant sounds and how they would have spread throughout the Chacoan landscape. These could be the voices of people, the sound of domestic animals like dogs and turkeys, the creation of stone tools or the sound of musical instruments. Within the American Southwest, these instruments include bone flutes, whistles, foot drums, copper bells and conch shell trumpets. </p>
<p>Soundshed maps reveal that a person standing at either of two neighboring great houses, Pueblo Alto and New Alto, located approximately 500 feet from each other, can hear a person shouting or speaking to a group at the other site. The patterns differ between the two maps because the terrain differs slightly between the two locations, and because the structures themselves block sound.</p>
<p>A third map models someone blowing a conch shell trumpet from immediately north of Casa Rinconada, a large ceremonial structure, at dawn on the summer solstice. </p>
<p>The sound spreads throughout the canyon, traveling to a number of mesa top shrines that often marked sacred locations and high points on the landscape. Perhaps audibility influenced the positioning of the shrines so ritual events occurring at Casa Rinconada could be heard? </p>
<p>Investigating how sound interacts with the built environment can reveal details about the importance of ritual. It can show us if sound was considered important by the ancestral Puebloan people, especially if shrines are consistently found in locations where people could hear rituals that were performed at a distance.</p>
<h2>The future of archaeoacoustics</h2>
<p>Our research presents a first step in the archaeoacoustic study of landscapes. Now we hope to expand our research by visiting Chaco Canyon to perform sound studies and record measurements in the field. We also plan to apply our model to other cultures, geographic areas and time periods. </p>
<p>Acoustic studies combined with other archaeological research contribute to a more holistic understanding of past cultures. The field has grown as more researchers expand their multidisciplinary pursuits, combining other fields of study with their archaeological approach. For example, advances in geography, physics, psychology, computer programming and other fields made our acoustic study possible. Previously, the study of archaeoacoustics at the landscape level had been out of reach due to technological limitations and a lack of tools. It is only now that computer processing power has caught up to our dreams. </p>
<p>Modeling tools like this one also offer the added benefit of allowing us to study what people heard at a site in any place or time without the need to travel to those locations. Instead, researchers can apply existing data found through a literature search, or measure the sound levels of noises or musical instruments to use as model inputs. This opens up new areas to be explored and studied.</p>
<p>Sound modeling can help researchers ask questions, and help everyone understand and relate to the ways that other people experienced their world. A sound model opens a new door into our understanding of the past.</p><img src="https://counter.theconversation.com/content/80861/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kristy Primeau is currently employed by the New York State Department of Environmental Conservation (DEC). DEC data was used in the article "Soundscapes in the Past: Investigating Sound at the Landscape Level". </span></em></p><p class="fine-print"><em><span>David E. Witt is currently employed by the New York State Department of Environmental Conservation (DEC). DEC data was used in the article "Soundscapes in the Past: Investigating Sound at the Landscape Level". David is also currently a member of the Government Affairs Committee of the Society for American Archaeology.</span></em></p>We tend to think of archaeological sites as dead silent – empty ruins left by past cultures. But this isn’t how the people who lived in and used these sites would have experienced them.Kristy E. Primeau, Registered Professional Archaeologist, PhD Candidate, University at Albany, State University of New YorkDavid E. Witt, Research Associate, University at BuffaloLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/576202016-04-13T05:35:24Z2016-04-13T05:35:24ZHere’s how tweets and check-ins can be used to spot early signs of gentrification<figure><img src="https://images.theconversation.com/files/118212/original/image-20160411-21989-4b94ps.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption"></span> <span class="attribution"><span class="source">from www.shutterstock.com</span></span></figcaption></figure><p>When you walk through a neighbourhood undergoing gentrification, you can sense it – the area is dominated by strange contradictions. Public spaces are populated by vagabonds and cool kids; abandoned buildings sit in disrepair next to trendy coffee shops; blocks of council housing abut glassy new developments. </p>
<p>Urbanists <a href="https://books.google.ca/books?id=KeNXAQAAQBAJ&source=gbs_book_other_versions">describe gentrification</a> as a form of urban migration, where a more affluent population displaces the original, lower-income population. In statistics, gentrification appears as the lowering of crime rates, rising housing prices and changes to the mix of people who live there. </p>
<p>If we could only predict where gentrification is likely to strike next, we might be able to alleviate its negative impacts – such as displacement – and take advantage of its more positive effects, which include economic growth. That’s why our <a href="http://www.cl.cam.ac.uk/%7Edh475/papers/www16.pdf">latest study</a> – conducted with colleagues at the University of Birmingham, Queen Mary University of London, and University College London – aimed to quantify the process of gentrification, and discover the warning signs. </p>
<h2>Detecting urban diversity</h2>
<p>We constructed four measures of urban social diversity using data from social media. By combining these measures with government statistics about deprivation, we were able to pinpoint a number of neighbourhoods undergoing gentrification in London.</p>
<p>Of course, social media is notoriously unsuitable for population studies, because of <a href="https://www.theguardian.com/technology/2016/jan/13/internet-not-conquered-digital-divide-rich-poor-world-bank-report">the “digital divide”</a>: the split between people who can access the internet and those who can’t exists even within urban areas – so information from social media only captures part of the overall picture. Twitter users in particular <a href="http://www.pewinternet.org/2015/08/19/the-demographics-of-social-media-users/">are known to be</a> predominantly young, affluent and living in urban areas. </p>
<p>But these are precisely the demographics responsible for gentrification. So, we used information from social media from 2010 and 2011 to define the “social diversity” of urban venues such as restaurants, bars, schools and parks. </p>
<p>Urban social diversity – in terms of population, economy and architecture – is known to be a factor in successful communities. In her famous book <a href="http://www.theguardian.com/books/2011/oct/14/jane-jacobs-death-and-life-rereading">The Death and Life of Great American Cities</a>, urban activist Jane Jacobs wrote that “cities differ from towns and suburbs in basic ways, and one of these is that cities are, by definition, full of strangers”. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/118209/original/image-20160411-21986-wh6qhu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/118209/original/image-20160411-21986-wh6qhu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/118209/original/image-20160411-21986-wh6qhu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/118209/original/image-20160411-21986-wh6qhu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/118209/original/image-20160411-21986-wh6qhu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/118209/original/image-20160411-21986-wh6qhu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/118209/original/image-20160411-21986-wh6qhu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Dropping in.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/davidabrahamovitch/8070182265/sizes/o/">David Abrahamovitch/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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</figure>
<p>In our work, we first measured the amount of strangers that a place brings together as the fraction of the social network of visitors who are connected on social media. This gave us an idea of whether a place tends to be frequented by strangers or friends. We further explored the diversity of these visitors in terms of their mobility preferences and spontaneity in choice of venues. Although we did not consider demographics or income levels, there is a known relationship between the wealth of people and the <a href="http://science.sciencemag.org/content/328/5981/1029">diversity of their geographical interactions</a>. </p>
<p>We studied the social network of 37,000 London users of <a href="https://twitter.com/">Twitter</a>, and combined it with what we knew about their mobility patterns from geo-located <a href="https://foursquare.com/">Foursquare</a> check-ins posted to their public profiles. </p>
<p>By studying the amount of strangers versus friends meeting at a bar, or the number of diverse versus similar individuals visiting an art gallery, we were able to quantify the overall diversity of London neighbourhoods, in terms of their visitors. </p>
<p>Networks are powerful representations of the relationships between people and places. Not only can we draw links between people where a relationship – such as friendship – exists between them; we can also draw connections between two places if a visitor has been to both. We can even connect the two networks, by drawing links between people in the social network who have visited specific spots in the place network. </p>
<p>In this way, we are able to extract the social network of a place, and the place network of a person. By the time we’d finished crunching the data, we could take stock of the range of people who had visited a specific place, and the different places visited by any individual.</p>
<p>When we compared the diversity of urban neighbourhoods with <a href="https://www.gov.uk/government/statistics/english-indices-of-deprivation-2010">official government statistics on deprivation</a>, we found that some highly deprived areas were also extremely socially diverse. In other words, there were lots of diverse social media users visiting some of London’s poorest neighbourhoods. </p>
<h2>Diminishing deprivation</h2>
<p>To find out what was going on, we took the newly published <a href="https://www.gov.uk/government/statistics/english-indices-of-deprivation-2015">deprivation indices for 2015</a> and looked for changes in the levels of deprivation from our study period in 2011. The relationship was striking. The areas where we saw high levels of social diversity and extreme deprivation in 2011, were exactly the same areas that had experienced the <a href="https://theconversation.com/heres-what-we-learned-from-mapping-out-englands-inequalities-48562">greatest decreases in deprivation</a> by 2016. </p>
<p>A prime example can be found in the London borough of Hackney. Anyone visiting Hackney might describe it in terms of the contradictions we mentioned before – but few of us could afford to live there today. In our study, Hackney was the highest ranking in deprivation and the highest ranking in social diversity in 2011. Between then and now, it has gone from the being the second most deprived neighbourhood in the country, to the 11th. </p>
<p>So, although social media may not be representative of the entire population, it can offer the key to measuring and understanding the processes of gentrification. Neither entirely good nor thoroughly bad, gentrification is a phenomenon that we should all watch out for. It will undoubtedly help to define how our cities transform in years to come.</p><img src="https://counter.theconversation.com/content/57620/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Desislava Hristova does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Social media is notoriously unsuitable for population studies, but these researchers have found a way to make the bias work in their favour.Desislava Hristova, PhD Candidate, University of CambridgeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/539172016-03-04T11:17:24Z2016-03-04T11:17:24ZHow we used a century of data to create a modern, digital geologic map of Alaska<figure><img src="https://images.theconversation.com/files/113756/original/image-20160303-9486-14d0nj9.png?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The biggest state has a brand new map.</span> <span class="attribution"><span class="source">Geologic Map of Alaska</span></span></figcaption></figure><p>Since <a href="http://www.simonwinchester.com/map">William Smith’s publication</a> of the first geologic map of England in 1815, geologists have used maps to show the distribution and character of rocks at the Earth’s surface, and display their interpretations of the underlying geology. These maps help guide exploration for natural resources and help users understand natural hazards and ecosystems.</p>
<p>When my colleagues and I began working on a new geologic map of Alaska in the late 1990s, we decided to structure it quite differently from the previous version, published back in 1980. This time around, we’d tap into Geographic Information Systems (GIS) technology. Though what we recently released is called the <a href="http://dx.doi.org/10.3133/sim3340">Geologic Map of Alaska</a>, it’s really a database from which many different maps can be created. </p>
<p>The advent of digital methods has revolutionized mapping. Printed maps are limited in how much they can show before the amount of detail obscures meaning. They’re also restricted to a single view of the information. Digital maps can store and display a variety of information, allowing users to focus on the characteristics of interest. Using GIS and digital data, many different maps can be created and displayed, allowing users of our new Alaska database to choose which aspects to display.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/113622/original/image-20160302-25881-1xc2g61.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/113622/original/image-20160302-25881-1xc2g61.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/113622/original/image-20160302-25881-1xc2g61.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=487&fit=crop&dpr=1 600w, https://images.theconversation.com/files/113622/original/image-20160302-25881-1xc2g61.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=487&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/113622/original/image-20160302-25881-1xc2g61.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=487&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/113622/original/image-20160302-25881-1xc2g61.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=612&fit=crop&dpr=1 754w, https://images.theconversation.com/files/113622/original/image-20160302-25881-1xc2g61.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=612&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/113622/original/image-20160302-25881-1xc2g61.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=612&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A U.S. Geological Survey party in the moraines of the Malaspina Glacier in Alaska, circa 1890.</span>
<span class="attribution"><a class="source" href="http://library.usgs.gov/photo/#/item/51ddacc4e4b0f72b4471ee15">U.S. Geological Survey</a></span>
</figcaption>
</figure>
<h2>New compilation of more than a century of data</h2>
<p>The United States is divided into quadrangles for mapping purposes; in Alaska, each measures one degree of latitude by two or three degrees of longitude – about 70 by 100 miles. Alaska is composed of 153 of these quadrangles. We started compiling a database and digitizing 1:250,000-scale quadrangle geologic maps, for which about two-thirds of the 153 quadrangles had been published. Many of these geologic maps had been completed after release of the 1980 map. We also found unpublished compilations for some additional quadrangles. </p>
<p>Then we added data from other available sources – maps published at other scales, journal articles, original field notes, aerial photos, Google Earth and new fieldwork. We scoured any sources we could think of that might have geological data about Alaska for inclusion in our new map, even going back to some of the Russian writings from prior to the <a href="https://history.state.gov/milestones/1866-1898/alaska-purchase">Alaska purchase in 1867</a>.</p>
<p>Having worked in Alaska for many years, I understand how little we know about the geology of Alaska compared to the conterminous U.S., due to factors including its vast size, its low population and limited infrastructure, and the complexity of its geology. Yet I was surprised how much we <em>do</em> know, just hidden away in forgotten or obscure documents.</p>
<figure class="align-right zoomable">
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<figcaption>
<span class="caption">The back cover of the new Geologic Map of Alaska’s pamphlet gives a sense of some of the earlier maps it’s updating.</span>
<span class="attribution"><span class="source">U.S. Geological Survey</span></span>
</figcaption>
</figure>
<p>Our sources span more than 100 years of data collection by a large number of geologists, each with a particular perspective. Many of the early geologic expeditions were limited in what they could see as they traveled; in general, there was no going back if you saw something today that made you want to take another look at something you saw two days ago. Often early expeditions were also producing the topographic maps as they went.</p>
<p>Each geologist was influenced by personal experience and the paradigms of the time. Prior to the advent of radioactive dating techniques, determining the age of rock units was dependent on finding fossils and understanding the geologic structures and stratigraphy. For instance, Father Hubbard, the “<a href="http://www.marywood.edu/archives/archival-exhibits/father-bernard-hubbard.html">Glacier Priest</a>,” <a href="https://books.google.com/books?q=editions:OCLC560491739&id=w7ygnQEACAAJ">studied the geology along the Alaska Peninsula</a> in the 1930s. Noting the coal beds, he thought the chain of volcanoes along the peninsula were due to the burning of coal deep underground. The advent of plate tectonic theory explains the volcanoes as a result of subduction and fits them into larger framework. While the presence of the volcanoes hasn’t changed, how we explain them has. I had to try to get into each geologist’s head, to attempt to understand what they saw and how the clues in the data they collected in the past could be interpreted within a modern plate tectonic paradigm.</p>
<p>Other challenges included determining precise locations from hand-drawn or reconnaissance maps. These early maps might not have complete contour lines; one map area I worked on had some mountains in the wrong spots and others were even missing. Essentially sketches, they were the best that could be done at the time.</p>
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<a href="https://images.theconversation.com/files/113791/original/image-20160303-13754-qseibx.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/113791/original/image-20160303-13754-qseibx.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/113791/original/image-20160303-13754-qseibx.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=553&fit=crop&dpr=1 600w, https://images.theconversation.com/files/113791/original/image-20160303-13754-qseibx.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=553&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/113791/original/image-20160303-13754-qseibx.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=553&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/113791/original/image-20160303-13754-qseibx.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=695&fit=crop&dpr=1 754w, https://images.theconversation.com/files/113791/original/image-20160303-13754-qseibx.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=695&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/113791/original/image-20160303-13754-qseibx.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=695&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A 1959 map of the Ruby quadrangle that served as source material for the new map.</span>
<span class="attribution"><span class="source">U.S. Geological Survey</span></span>
</figcaption>
</figure>
<p>We also had to deal with reconciling the many different styles of geologic maps produced over the decades, along with poorly registered illustrations and lack of sample location information in published literature. For example, an early map of the Ruby quadrangle in west central Alaska was based on a crude, exploratory-quality topographic map; we had to redraw it, trying to more accurately locate geologic features, before we could digitize it.</p>
<p>Based on local geology, we compiled over 15,000 map units from the source maps. Each map unit was defined by distinctive rock units, using characteristics such as age, rock type and environment of formation – beach deposit versus deep ocean, for instance, or lava flow versus granite. By grouping similar map units together, we were able to reduce these to 1,350 unique map units. Further reduction resulted in about 450 map units for the detailed digital release and a generalized 220 units for the eventual print version. The resulting map divides the state along geologic characteristics rather than divided into units based on longitude and latitude.</p>
<p>The published digital map allows the user to zoom from the generalized version to the detailed version. The associated database contains more than a dozen interrelated tables that make this release special; and unlike previous print-only releases, the database is designed to be updated.</p>
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<a href="https://images.theconversation.com/files/113783/original/image-20160303-9490-rnpqv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/113783/original/image-20160303-9490-rnpqv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/113783/original/image-20160303-9490-rnpqv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/113783/original/image-20160303-9490-rnpqv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/113783/original/image-20160303-9490-rnpqv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/113783/original/image-20160303-9490-rnpqv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/113783/original/image-20160303-9490-rnpqv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/113783/original/image-20160303-9490-rnpqv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Warren Coonrad of the USGS working in southwest Alaska in 1975.</span>
<span class="attribution"><span class="source">U.S. Geological Survey</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Though I drove the effort, I stood on the shoulders of giants. Current USGS staff and volunteers and nearly a dozen retired USGS staff (Emeritus) contributed to the effort. Digital support came from many, as we had to capture data, design the spatial databases and package the data for release.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/113788/original/image-20160303-9463-1vo02bz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/113788/original/image-20160303-9463-1vo02bz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/113788/original/image-20160303-9463-1vo02bz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=468&fit=crop&dpr=1 600w, https://images.theconversation.com/files/113788/original/image-20160303-9463-1vo02bz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=468&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/113788/original/image-20160303-9463-1vo02bz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=468&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/113788/original/image-20160303-9463-1vo02bz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=588&fit=crop&dpr=1 754w, https://images.theconversation.com/files/113788/original/image-20160303-9463-1vo02bz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=588&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/113788/original/image-20160303-9463-1vo02bz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=588&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Anchorage area, in the new map.</span>
<span class="attribution"><span class="source">Geologic Map of Alaska</span></span>
</figcaption>
</figure>
<h2>A geologic map for the 21st century</h2>
<p>Previous generations commonly used hand-drawn overlays to display different types of map data. To discover relationships between data types, geologists had to mentally visualize these relationships or draw new maps.</p>
<p>Today, with GIS, this process can be computer-aided. Choosing the data to display, GIS-capable users can generate derivative maps, or query the map and database for a variety of characteristics. GIS allows the user to explore relationships between data sets, test theories and otherwise use this geologic database of Alaska as an analysis tool. Users can incorporate additional data – for example, geochemical analyses – to characterize geologic units. Alternatively, a user could compare plant distributions with underlying geology to evaluate potential relationships.</p>
<p>The map and database are analogous to a map that shows the roads, but not the route. It doesn’t tell you which path to take until you figure out where you’re going. Like a spreadsheet, this map allows the user to ask questions.</p>
<p>As designed, the map is intended for a wide audience, from Alaska Native Corporations and land management agencies to academic institutions and mining and energy companies. This map provides a broad overview, as well as detailed information, which enhance a user’s ability to search for patterns and trends otherwise not apparent, and its digital form aids users in incorporating other data sets.</p><img src="https://counter.theconversation.com/content/53917/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Frederic Wilson receives funding from the U.S. Geological Survey and the National Park Service. He is a Fellow of the Geological Society of America and a member of the Alaska Geological Society</span></em></p>On printed maps, piling on the detail risks obscuring the meaning. This new digital map is really more of a database from which users can create different versions that match their own interests.Frederic Wilson, Research Geologist, US Geological SurveyLicensed as Creative Commons – attribution, no derivatives.