{"id":392722,"date":"2019-02-13T04:50:50","date_gmt":"2019-02-13T12:50:50","guid":{"rendered":"http:\/\/www.esri.com\/arcgis-blog\/?post_type=blog&p=392722"},"modified":"2020-06-25T10:57:50","modified_gmt":"2020-06-25T17:57:50","slug":"the-cartography-of-time-magnitude-and-alert-levels","status":"publish","type":"blog","link":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-living-atlas\/mapping\/the-cartography-of-time-magnitude-and-alert-levels","title":{"rendered":"Earthquake Mapping Part II: The Cartography of Time, Magnitude, and Alert Levels"},"author":8492,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","format":"standard","meta":{"_acf_changed":false,"_searchwp_excluded":""},"categories":[22941],"tags":[43101,42641,26131,268131],"industry":[],"product":[36581,36551],"class_list":["post-392722","blog","type-blog","status-publish","format-standard","hentry","category-mapping","tag-arcgis-living-atlas-of-the-world","tag-arcgis-online","tag-earthquake","tag-living-atlas","product-arcgis-living-atlas","product-arcgis-online"],"acf":{"short_description":"Let's meaningfully visualize 60 possible earthquake combinations using Live Feed data available in the Living Atlas.","flexible_content":[{"acf_fc_layout":"content","content":"

<\/h2>\n

Welcome to Part II of Earthquake Mapping using Esri’s Live Feed data.<\/p>\n

In Part I<\/a> we used an Arcade expression to take multiple fields in our data and combined them into one set of symbols. This resulted in 60 possible symbol combinations!<\/p>\n

Here in Part II we are going to stylize the results of that Arcade expression in a meaningful way and create an earthquake map<\/a> that immediately conveys the critical information that needs to be seen.\u00a0 We will do this by taking our combined fields and applying them to a symbol with varying color, size, and stroke to tell the complete story of the earthquake data. Get ready!<\/p>\n

 <\/p>\n"},{"acf_fc_layout":"image","image":{"ID":395472,"id":395472,"title":"eem_18_earthquakes27","filename":"eem_18_earthquakes27.jpg","filesize":35426,"url":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2018\/12\/eem_18_earthquakes27.jpg","link":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-living-atlas\/mapping\/the-cartography-of-time-magnitude-and-alert-levels\/eem_18_earthquakes27","alt":"Image of Drop! Cover! Hold On!","author":"8492","description":"","caption":"","name":"eem_18_earthquakes27","status":"inherit","uploaded_to":392722,"date":"2018-12-30 04:43:46","modified":"2019-02-02 03:42:09","menu_order":0,"mime_type":"image\/jpeg","type":"image","subtype":"jpeg","icon":"https:\/\/www.esri.com\/arcgis-blog\/wp-includes\/images\/media\/default.png","width":1154,"height":381,"sizes":{"thumbnail":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2018\/12\/eem_18_earthquakes27-150x150.jpg","thumbnail-width":150,"thumbnail-height":150,"medium":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2018\/12\/eem_18_earthquakes27-300x99.jpg","medium-width":300,"medium-height":99,"medium_large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2018\/12\/eem_18_earthquakes27-768x254.jpg","medium_large-width":768,"medium_large-height":254,"large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2018\/12\/eem_18_earthquakes27-1024x338.jpg","large-width":1024,"large-height":338,"1536x1536":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2018\/12\/eem_18_earthquakes27.jpg","1536x1536-width":1154,"1536x1536-height":381,"2048x2048":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2018\/12\/eem_18_earthquakes27.jpg","2048x2048-width":1154,"2048x2048-height":381,"card_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2018\/12\/eem_18_earthquakes27-826x273.jpg","card_image-width":826,"card_image-height":273,"wide_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2018\/12\/eem_18_earthquakes27.jpg","wide_image-width":1154,"wide_image-height":381}},"image_position":"center","orientation":"horizontal","hyperlink":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2018\/12\/eem_18_earthquakes27.jpg"},{"acf_fc_layout":"content","content":"

 <\/p>\n

Earthquake Data in the Living Atlas<\/h2>\n

The Living Atlas of the World<\/a>\u00a0hosts\u00a0recent global earthquakes<\/a> from the U.S. Geological Survey (USGS) and their Prompt Assessment of Global Earthquakes for Response (PAGER<\/a>) program.<\/p>\n

This Live Feed<\/a> is updated every five minutes and has fields detailing individual earthquake information including an event’s ID, Hours Old, Magnitude, Location, and Alert Level.<\/p>\n

 <\/p>\n"},{"acf_fc_layout":"image","image":{"ID":424932,"id":424932,"title":"eem_18_earthquakes183","filename":"eem_18_earthquakes183.jpg","filesize":728574,"url":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes183.jpg","link":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-living-atlas\/mapping\/the-cartography-of-time-magnitude-and-alert-levels\/eem_18_earthquakes183","alt":"A home collapsed in San Francisco's Marina District a day after the 6.9 magnitude Loma Prieta earthquake struck the Bay Area in California on October 17, 1989.","author":"8492","description":"","caption":"A home collapsed in San Francisco's Marina District a day after the 6.9 magnitude Loma Prieta earthquake struck the Bay Area in California on October 17, 1989.","name":"eem_18_earthquakes183","status":"inherit","uploaded_to":392722,"date":"2019-01-30 03:13:23","modified":"2019-02-02 03:31:30","menu_order":0,"mime_type":"image\/jpeg","type":"image","subtype":"jpeg","icon":"https:\/\/www.esri.com\/arcgis-blog\/wp-includes\/images\/media\/default.png","width":1679,"height":1095,"sizes":{"thumbnail":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes183-150x150.jpg","thumbnail-width":150,"thumbnail-height":150,"medium":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes183-300x196.jpg","medium-width":300,"medium-height":196,"medium_large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes183-768x501.jpg","medium_large-width":768,"medium_large-height":501,"large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes183-1024x668.jpg","large-width":1024,"large-height":668,"1536x1536":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes183.jpg","1536x1536-width":1536,"1536x1536-height":1002,"2048x2048":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes183.jpg","2048x2048-width":1679,"2048x2048-height":1095,"card_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes183-713x465.jpg","card_image-width":713,"card_image-height":465,"wide_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes183-1656x1080.jpg","wide_image-width":1656,"wide_image-height":1080}},"image_position":"center","orientation":"horizontal","hyperlink":"https:\/\/commons.wikimedia.org\/wiki\/File:A_home_collapses_in_the_city%27s_Marina_District_a_day_after_the_1989_Loma_Prieta_earthquake.jpg"},{"acf_fc_layout":"content","content":"

 <\/p>\n

What Should We See on Our Earthquake Map?<\/h2>\n

Earthquakes are powerful and scary with many factors of concern that need to be represented on our map. Having been through many myself I know that earthquakes happen unexpectedly and vary in their size,\u00a0intensity,<\/a> and severity for people and the environment.<\/p>\n

Earthquakes are usually not isolated incidents. They have aftershock<\/a> events in the same vicinity that unfold within a few hours, days, or even years of the initial incident. According to\u00a0plate tectonics<\/a>\u00a0earthquakes\u00a0occur within the same general areas and visualizing them this way can show patterns and trends.<\/p>\n

The information that should stand out on our map:<\/p>\n

    \n
  1. When was the earthquake?<\/li>\n
  2. How big was the earthquake?<\/li>\n
  3. What are the impacts on people and the environment?<\/li>\n<\/ol>\n

    The earthquake data\u00a0has three fields<\/a>\u00a0to make this happen: Hours Old, Magnitude, and Alert Level (See Part I<\/a>\u00a0of this earthquake blog to find out how these were combined in Arcade).<\/em><\/p>\n

     <\/p>\n

    Map Purpose and Design<\/h2>\n

    The purpose of this\u00a0map<\/a> is to visualize the earthquake data as intuitively and elegantly as possible with our end goal being to update the Live Feed earthquake data that is available in the Living Atlas.<\/p>\n

    This is a web map<\/a> with hundreds of dynamic points of data. I was asked to work within these design requirements:<\/p>\n

      \n
    1. Design an easy to use ArcGIS Online web map with one earthquake\u00a0layer<\/a>\u00a0in the Contents pane.<\/li>\n
    2. Display the earthquake data so our viewer can quickly determine and differentiate an earthquake’s Time, Magnitude, and Alert Level.<\/li>\n
    3. Use out of the box ArcGIS Online map symbology that is quickly retrieved, available to all users across the platform, and can be easily replicated.<\/li>\n
    4. Create a map palette that has a visual hierarchy and is also acceptable for color blindness.<\/li>\n
    5. The cartography must work on both a Light or Dark Basemap with no change to the story focus (a challenging feat indeed!).<\/li>\n<\/ol>\n

       <\/p>\n

      A Simple Circle Symbol (But Really Not Simple)<\/em><\/h2>\n

      The symbol needs to be intuitive and differentiate hundreds of global earthquakes, with three variables, as simply as possible, on a map that is always changing.<\/p>\n

      In 1967 French cartographer Jaques Bertin<\/a>\u00a0developed the concept of visual variables in his book Semiologie Graphique<\/em> (Esri republished<\/a>\u00a0in 2010<\/a>). This book is considered to be a\u00a0foundational work in information design, visualization, and the first\u00a0analytic theory of graphic representation.<\/p>\n

      Bertin’s graphic system has six main categories of visual variables which include: size,\u00a0value, texture, color, orientation, and shape; along with two other variables that dissect an items space: position and position in a series. We can apply his visual variables framework to our earthquake data.<\/p>\n

      He writes about the visual variables:<\/p>\n

      They f<\/em>orm the world of images. With them the designer suggests perspective, the painter reality, the graphic draftsman ordered relationships, and the cartographer space (Bertin. 1983, p. 42).\u00a0<\/em><\/p>\n

       <\/p>\n"},{"acf_fc_layout":"image","image":{"ID":426152,"id":426152,"title":"eem_18_earthquakes185","filename":"eem_18_earthquakes185.jpg","filesize":250172,"url":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes185.jpg","link":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-living-atlas\/mapping\/the-cartography-of-time-magnitude-and-alert-levels\/eem_18_earthquakes185","alt":"Picture of the sign at the epicenter of the Loma Prieta earthquake. A six-mile hike in Nisene Marks State Park will take you to the epicenter of the Loma Prieta earthquake.","author":"8492","description":"","caption":"A six-mile hike in Nisene Marks State Park will take you to the epicenter of the Loma Prieta earthquake.","name":"eem_18_earthquakes185","status":"inherit","uploaded_to":392722,"date":"2019-01-30 17:47:41","modified":"2019-02-02 03:31:01","menu_order":0,"mime_type":"image\/jpeg","type":"image","subtype":"jpeg","icon":"https:\/\/www.esri.com\/arcgis-blog\/wp-includes\/images\/media\/default.png","width":720,"height":540,"sizes":{"thumbnail":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes185-150x150.jpg","thumbnail-width":150,"thumbnail-height":150,"medium":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes185-300x225.jpg","medium-width":300,"medium-height":225,"medium_large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes185.jpg","medium_large-width":720,"medium_large-height":540,"large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes185.jpg","large-width":720,"large-height":540,"1536x1536":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes185.jpg","1536x1536-width":720,"1536x1536-height":540,"2048x2048":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes185.jpg","2048x2048-width":720,"2048x2048-height":540,"card_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes185-620x465.jpg","card_image-width":620,"card_image-height":465,"wide_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes185.jpg","wide_image-width":720,"wide_image-height":540}},"image_position":"center","orientation":"horizontal","hyperlink":"https:\/\/commons.wikimedia.org\/wiki\/File:Loma_prieta_epicenter_sign.jpg"},{"acf_fc_layout":"content","content":"

       <\/p>\n

      Since all earthquakes have an epicenter<\/a>\u00a0using the shape of a point or circle symbol to represent each earthquake is a good place to start. This symbol is also friendly to overlapping or stacking, and using transparency for visualization.<\/p>\n

       <\/p>\n"},{"acf_fc_layout":"image","image":{"ID":420702,"id":420702,"title":"eem_18_earthquakes150","filename":"eem_18_earthquakes150.jpg","filesize":73476,"url":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes150.jpg","link":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-living-atlas\/mapping\/the-cartography-of-time-magnitude-and-alert-levels\/eem_18_earthquakes150","alt":"Three black dots.","author":"8492","description":"","caption":"","name":"eem_18_earthquakes150","status":"inherit","uploaded_to":392722,"date":"2019-01-25 17:54:03","modified":"2019-02-02 03:37:03","menu_order":0,"mime_type":"image\/jpeg","type":"image","subtype":"jpeg","icon":"https:\/\/www.esri.com\/arcgis-blog\/wp-includes\/images\/media\/default.png","width":3035,"height":568,"sizes":{"thumbnail":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes150-150x150.jpg","thumbnail-width":150,"thumbnail-height":150,"medium":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes150-300x56.jpg","medium-width":300,"medium-height":56,"medium_large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes150-768x144.jpg","medium_large-width":768,"medium_large-height":144,"large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes150-1024x192.jpg","large-width":1024,"large-height":192,"1536x1536":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes150.jpg","1536x1536-width":1536,"1536x1536-height":287,"2048x2048":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes150.jpg","2048x2048-width":2048,"2048x2048-height":383,"card_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes150-826x155.jpg","card_image-width":826,"card_image-height":155,"wide_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes150-1920x359.jpg","wide_image-width":1920,"wide_image-height":359}},"image_position":"center","orientation":"horizontal","hyperlink":""},{"acf_fc_layout":"content","content":"

      Data Field #1: Hours Old<\/h2>\n

      Time is a critical component for our map’s message. Using color to bring out time will allow the visual hierarchy to show:<\/p>\n

        \n
      1. Where are the earthquakes that are happening right now?<\/li>\n
      2. What happened recently because there may be aftershocks?<\/li>\n
      3. What happened lately to see some patterns or trends?<\/li>\n<\/ol>\n

        The Live Feed data goes back three months and has a field called \u201cHours Old\u201d which can be divided into three time periods:<\/p>\n

         <\/p>\n"},{"acf_fc_layout":"image","image":{"ID":420722,"id":420722,"title":"eem_18_earthquakes107","filename":"eem_18_earthquakes107.jpg","filesize":74938,"url":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes107.jpg","link":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-living-atlas\/mapping\/the-cartography-of-time-magnitude-and-alert-levels\/eem_18_earthquakes107","alt":"Chart showing the three colors of Red, Yellow, and Gray and their visual hierarchy.","author":"8492","description":"","caption":"","name":"eem_18_earthquakes107","status":"inherit","uploaded_to":392722,"date":"2019-01-25 17:56:52","modified":"2019-02-02 03:36:37","menu_order":0,"mime_type":"image\/jpeg","type":"image","subtype":"jpeg","icon":"https:\/\/www.esri.com\/arcgis-blog\/wp-includes\/images\/media\/default.png","width":732,"height":275,"sizes":{"thumbnail":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes107-150x150.jpg","thumbnail-width":150,"thumbnail-height":150,"medium":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes107-300x113.jpg","medium-width":300,"medium-height":113,"medium_large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes107.jpg","medium_large-width":732,"medium_large-height":275,"large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes107.jpg","large-width":732,"large-height":275,"1536x1536":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes107.jpg","1536x1536-width":732,"1536x1536-height":275,"2048x2048":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes107.jpg","2048x2048-width":732,"2048x2048-height":275,"card_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes107.jpg","card_image-width":732,"card_image-height":275,"wide_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes107.jpg","wide_image-width":732,"wide_image-height":275}},"image_position":"center","orientation":"horizontal","hyperlink":""},{"acf_fc_layout":"image","image":{"ID":419922,"id":419922,"title":"eem_18_earthquakes134","filename":"eem_18_earthquakes134.jpg","filesize":27282,"url":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes134.jpg","link":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-living-atlas\/mapping\/the-cartography-of-time-magnitude-and-alert-levels\/eem_18_earthquakes134","alt":"Plain white bar.","author":"8492","description":"","caption":"","name":"eem_18_earthquakes134","status":"inherit","uploaded_to":392722,"date":"2019-01-24 22:25:41","modified":"2019-02-02 03:37:11","menu_order":0,"mime_type":"image\/jpeg","type":"image","subtype":"jpeg","icon":"https:\/\/www.esri.com\/arcgis-blog\/wp-includes\/images\/media\/default.png","width":3434,"height":233,"sizes":{"thumbnail":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes134-150x150.jpg","thumbnail-width":150,"thumbnail-height":150,"medium":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes134-300x20.jpg","medium-width":300,"medium-height":20,"medium_large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes134-768x52.jpg","medium_large-width":768,"medium_large-height":52,"large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes134-1024x69.jpg","large-width":1024,"large-height":69,"1536x1536":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes134.jpg","1536x1536-width":1536,"1536x1536-height":104,"2048x2048":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes134.jpg","2048x2048-width":2048,"2048x2048-height":139,"card_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes134-826x56.jpg","card_image-width":826,"card_image-height":56,"wide_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes134-1920x130.jpg","wide_image-width":1920,"wide_image-height":130}},"image_position":"center","orientation":"horizontal","hyperlink":""},{"acf_fc_layout":"content","content":"

        <\/h2>\n

        Data Field #2: Magnitude<\/h2>\n

        The USGS determines the size of an earthquake by\u00a0Richter magnitude<\/a>\u00a0which measures the energy released at the source of the earthquake and is recorded as the maximum motion observed by a seismograph. The earthquake’s severity is ranked by\u00a0The Modified Mercalli Intensity Scale.<\/a><\/p>\n

         <\/p>\n"},{"acf_fc_layout":"image","image":{"ID":424942,"id":424942,"title":"eem_18_earthquakes182","filename":"eem_18_earthquakes182.jpg","filesize":153964,"url":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes182.jpg","link":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-living-atlas\/mapping\/the-cartography-of-time-magnitude-and-alert-levels\/eem_18_earthquakes182","alt":"The Cypress Structure in Oakland, California after it collapsed during the 1989 Loma Prieta earthquake.","author":"8492","description":"","caption":"The Cypress Structure in Oakland, California after it collapsed during the 1989 Loma Prieta earthquake.","name":"eem_18_earthquakes182","status":"inherit","uploaded_to":392722,"date":"2019-01-30 03:13:52","modified":"2019-02-02 03:31:20","menu_order":0,"mime_type":"image\/jpeg","type":"image","subtype":"jpeg","icon":"https:\/\/www.esri.com\/arcgis-blog\/wp-includes\/images\/media\/default.png","width":758,"height":512,"sizes":{"thumbnail":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes182-150x150.jpg","thumbnail-width":150,"thumbnail-height":150,"medium":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes182-300x203.jpg","medium-width":300,"medium-height":203,"medium_large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes182.jpg","medium_large-width":758,"medium_large-height":512,"large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes182.jpg","large-width":758,"large-height":512,"1536x1536":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes182.jpg","1536x1536-width":758,"1536x1536-height":512,"2048x2048":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes182.jpg","2048x2048-width":758,"2048x2048-height":512,"card_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes182-688x465.jpg","card_image-width":688,"card_image-height":465,"wide_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes182.jpg","wide_image-width":758,"wide_image-height":512}},"image_position":"center","orientation":"horizontal","hyperlink":"https:\/\/www.mercurynews.com\/2014\/10\/16\/loma-prieta-25-years-later-your-memories\/"},{"acf_fc_layout":"image","image":{"ID":419922,"id":419922,"title":"eem_18_earthquakes134","filename":"eem_18_earthquakes134.jpg","filesize":27282,"url":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes134.jpg","link":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-living-atlas\/mapping\/the-cartography-of-time-magnitude-and-alert-levels\/eem_18_earthquakes134","alt":"Plain white bar.","author":"8492","description":"","caption":"","name":"eem_18_earthquakes134","status":"inherit","uploaded_to":392722,"date":"2019-01-24 22:25:41","modified":"2019-02-02 03:37:11","menu_order":0,"mime_type":"image\/jpeg","type":"image","subtype":"jpeg","icon":"https:\/\/www.esri.com\/arcgis-blog\/wp-includes\/images\/media\/default.png","width":3434,"height":233,"sizes":{"thumbnail":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes134-150x150.jpg","thumbnail-width":150,"thumbnail-height":150,"medium":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes134-300x20.jpg","medium-width":300,"medium-height":20,"medium_large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes134-768x52.jpg","medium_large-width":768,"medium_large-height":52,"large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes134-1024x69.jpg","large-width":1024,"large-height":69,"1536x1536":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes134.jpg","1536x1536-width":1536,"1536x1536-height":104,"2048x2048":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes134.jpg","2048x2048-width":2048,"2048x2048-height":139,"card_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes134-826x56.jpg","card_image-width":826,"card_image-height":56,"wide_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes134-1920x130.jpg","wide_image-width":1920,"wide_image-height":130}},"image_position":"center","orientation":"horizontal","hyperlink":""},{"acf_fc_layout":"content","content":"

        Filtering the Data<\/h2>\n

        According to the Modified Mercalli scale\u00a0earthquakes that are within the range of 4-4.9 magnitude are detectable by people outdoors and are strong enough to wake some people up at night. This is a good threshold for representation on our map.<\/p>\n

        Additionally we want to only only display those earthquakes that are > 4 magnitude because the USGS collects information on smaller magnitude earthquakes; however, only in the United States (< 3.9 magnitude). If we were to include all the data that comes with this map service there maybe an impression that more seismic activity is happening in the United States when that is not the case. There are just different levels of detail in some places than there are in others.<\/p>\n

        We want the data balanced and even across the globe and this is easily done by applying an ArcGIS Online\u00a0filter<\/a>\u00a0(explained in detail in\u00a0Earthquake Mapping Part I <\/a>)<\/em>.<\/p>\n

         <\/p>\n

        Complete Earthquake Dataset<\/p>\n"},{"acf_fc_layout":"image","image":{"ID":436332,"id":436332,"title":"eem_18_earthquakes214","filename":"eem_18_earthquakes214-1.jpg","filesize":128611,"url":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/02\/eem_18_earthquakes214-1.jpg","link":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-living-atlas\/mapping\/the-cartography-of-time-magnitude-and-alert-levels\/eem_18_earthquakes214-2","alt":"Complete earthquake dataset.","author":"8492","description":"","caption":"","name":"eem_18_earthquakes214-2","status":"inherit","uploaded_to":392722,"date":"2019-02-13 13:08:53","modified":"2019-02-13 13:09:31","menu_order":0,"mime_type":"image\/jpeg","type":"image","subtype":"jpeg","icon":"https:\/\/www.esri.com\/arcgis-blog\/wp-includes\/images\/media\/default.png","width":1390,"height":725,"sizes":{"thumbnail":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/02\/eem_18_earthquakes214-1-150x150.jpg","thumbnail-width":150,"thumbnail-height":150,"medium":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/02\/eem_18_earthquakes214-1-300x156.jpg","medium-width":300,"medium-height":156,"medium_large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/02\/eem_18_earthquakes214-1-768x401.jpg","medium_large-width":768,"medium_large-height":401,"large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/02\/eem_18_earthquakes214-1-1024x534.jpg","large-width":1024,"large-height":534,"1536x1536":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/02\/eem_18_earthquakes214-1.jpg","1536x1536-width":1390,"1536x1536-height":725,"2048x2048":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/02\/eem_18_earthquakes214-1.jpg","2048x2048-width":1390,"2048x2048-height":725,"card_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/02\/eem_18_earthquakes214-1-826x431.jpg","card_image-width":826,"card_image-height":431,"wide_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/02\/eem_18_earthquakes214-1.jpg","wide_image-width":1390,"wide_image-height":725}},"image_position":"center","orientation":"horizontal","hyperlink":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/02\/eem_18_earthquakes214-1.jpg"},{"acf_fc_layout":"content","content":"

         <\/p>\n

        Filtered by\u00a0 > 4 Magnitude<\/p>\n"},{"acf_fc_layout":"image","image":{"ID":436322,"id":436322,"title":"eem_18_earthquakes215","filename":"eem_18_earthquakes215.jpg","filesize":124156,"url":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/02\/eem_18_earthquakes215.jpg","link":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-living-atlas\/mapping\/the-cartography-of-time-magnitude-and-alert-levels\/eem_18_earthquakes215","alt":"Filtered by > 4 Magnitude.","author":"8492","description":"","caption":"","name":"eem_18_earthquakes215","status":"inherit","uploaded_to":392722,"date":"2019-02-13 13:07:50","modified":"2019-02-13 13:08:17","menu_order":0,"mime_type":"image\/jpeg","type":"image","subtype":"jpeg","icon":"https:\/\/www.esri.com\/arcgis-blog\/wp-includes\/images\/media\/default.png","width":1391,"height":728,"sizes":{"thumbnail":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/02\/eem_18_earthquakes215-150x150.jpg","thumbnail-width":150,"thumbnail-height":150,"medium":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/02\/eem_18_earthquakes215-300x157.jpg","medium-width":300,"medium-height":157,"medium_large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/02\/eem_18_earthquakes215-768x402.jpg","medium_large-width":768,"medium_large-height":402,"large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/02\/eem_18_earthquakes215-1024x536.jpg","large-width":1024,"large-height":536,"1536x1536":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/02\/eem_18_earthquakes215.jpg","1536x1536-width":1391,"1536x1536-height":728,"2048x2048":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/02\/eem_18_earthquakes215.jpg","2048x2048-width":1391,"2048x2048-height":728,"card_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/02\/eem_18_earthquakes215-826x432.jpg","card_image-width":826,"card_image-height":432,"wide_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/02\/eem_18_earthquakes215.jpg","wide_image-width":1391,"wide_image-height":728}},"image_position":"center","orientation":"horizontal","hyperlink":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/02\/eem_18_earthquakes215.jpg"},{"acf_fc_layout":"content","content":"

         <\/p>\n

        Now that our data is filtered we can place the earthquakes in four classifications using a\u00a0graduated symbol<\/a>. The circle will increase or decrease in size as a reflection of it’s magnitude.<\/p>\n

         <\/p>\n"},{"acf_fc_layout":"image","image":{"ID":422452,"id":422452,"title":"eem_18_earthquakes164","filename":"eem_18_earthquakes164.jpg","filesize":71986,"url":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes164.jpg","link":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-living-atlas\/mapping\/the-cartography-of-time-magnitude-and-alert-levels\/eem_18_earthquakes164","alt":"Chart demonstrating color and size of circle symbol.","author":"8492","description":"","caption":"","name":"eem_18_earthquakes164","status":"inherit","uploaded_to":392722,"date":"2019-01-28 18:07:23","modified":"2019-02-02 03:34:47","menu_order":0,"mime_type":"image\/jpeg","type":"image","subtype":"jpeg","icon":"https:\/\/www.esri.com\/arcgis-blog\/wp-includes\/images\/media\/default.png","width":600,"height":468,"sizes":{"thumbnail":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes164-150x150.jpg","thumbnail-width":150,"thumbnail-height":150,"medium":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes164-300x234.jpg","medium-width":300,"medium-height":234,"medium_large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes164.jpg","medium_large-width":600,"medium_large-height":468,"large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes164.jpg","large-width":600,"large-height":468,"1536x1536":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes164.jpg","1536x1536-width":600,"1536x1536-height":468,"2048x2048":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes164.jpg","2048x2048-width":600,"2048x2048-height":468,"card_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes164-596x465.jpg","card_image-width":596,"card_image-height":465,"wide_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes164.jpg","wide_image-width":600,"wide_image-height":468}},"image_position":"center","orientation":"horizontal","hyperlink":""},{"acf_fc_layout":"content","content":"

         <\/p>\n

        Data Field #3: Alert Level<\/h2>\n

         <\/p>\n"},{"acf_fc_layout":"image","image":{"ID":418622,"id":418622,"title":"eem_18_earthquakes118","filename":"eem_18_earthquakes118.jpg","filesize":68339,"url":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes118.jpg","link":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-living-atlas\/mapping\/the-cartography-of-time-magnitude-and-alert-levels\/eem_18_earthquakes118","alt":"Graphic showing the USGS PAGER levels.","author":"8492","description":"","caption":"","name":"eem_18_earthquakes118","status":"inherit","uploaded_to":392722,"date":"2019-01-24 15:57:28","modified":"2019-02-02 03:39:01","menu_order":0,"mime_type":"image\/jpeg","type":"image","subtype":"jpeg","icon":"https:\/\/www.esri.com\/arcgis-blog\/wp-includes\/images\/media\/default.png","width":680,"height":142,"sizes":{"thumbnail":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes118-150x142.jpg","thumbnail-width":150,"thumbnail-height":142,"medium":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes118-300x63.jpg","medium-width":300,"medium-height":63,"medium_large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes118.jpg","medium_large-width":680,"medium_large-height":142,"large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes118.jpg","large-width":680,"large-height":142,"1536x1536":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes118.jpg","1536x1536-width":680,"1536x1536-height":142,"2048x2048":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes118.jpg","2048x2048-width":680,"2048x2048-height":142,"card_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes118.jpg","card_image-width":680,"card_image-height":142,"wide_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes118.jpg","wide_image-width":680,"wide_image-height":142}},"image_position":"center","orientation":"horizontal","hyperlink":""},{"acf_fc_layout":"content","content":"

         <\/p>\n

        The USGS’s PAGER<\/a> program is an automated system for rapidly estimating the shaking distribution, the number of people and settlements exposed to severe shaking, the range of possible fatalities, and economic losses. The estimated losses trigger the appropriate color-coded alert which determines the suggested levels of response (Red, Orange, Yellow, Green, or None Issued).<\/p>\n

        In this respect (for our map) not all earthquakes need to be represented equally.\u00a0 A 6.5 magnitude earthquake that happens in an area that does not effect people or the environment versus a 6.5 magnitude earthquake that is devastating for a certain area or region – our map will need to display these both differently.\u00a0 With that said, every earthquake record is important for visualizing patterns and trends, but the PAGER Alert Levels will be the most important part of the map story since this measures the earthquake’s impact on people and the environment.<\/p>\n

         <\/p>\n"},{"acf_fc_layout":"image","image":{"ID":424952,"id":424952,"title":"eem_18_earthquakes184","filename":"eem_18_earthquakes184.jpg","filesize":243694,"url":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes184.jpg","link":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-living-atlas\/mapping\/the-cartography-of-time-magnitude-and-alert-levels\/eem_18_earthquakes184","alt":"The top deck of the Nimitz Freeway in Oakland, California collapsed down onto the lower deck during the 1989 Loma Prieta earthquake.","author":"8492","description":"","caption":"The top deck of the Nimitz Freeway in Oakland, California collapsed down onto the lower deck during the 1989 Loma Prieta earthquake.","name":"eem_18_earthquakes184","status":"inherit","uploaded_to":392722,"date":"2019-01-30 03:17:56","modified":"2019-02-02 03:31:13","menu_order":0,"mime_type":"image\/jpeg","type":"image","subtype":"jpeg","icon":"https:\/\/www.esri.com\/arcgis-blog\/wp-includes\/images\/media\/default.png","width":1024,"height":576,"sizes":{"thumbnail":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes184-150x150.jpg","thumbnail-width":150,"thumbnail-height":150,"medium":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes184-300x169.jpg","medium-width":300,"medium-height":169,"medium_large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes184-768x432.jpg","medium_large-width":768,"medium_large-height":432,"large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes184-1024x576.jpg","large-width":1024,"large-height":576,"1536x1536":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes184.jpg","1536x1536-width":1024,"1536x1536-height":576,"2048x2048":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes184.jpg","2048x2048-width":1024,"2048x2048-height":576,"card_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes184-826x465.jpg","card_image-width":826,"card_image-height":465,"wide_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes184.jpg","wide_image-width":1024,"wide_image-height":576}},"image_position":"center","orientation":"horizontal","hyperlink":"https:\/\/www.sfchronicle.com\/chronicle_vault\/article\/Loma-Prieta-quake-at-28-Long-forgotten-photos-12281981.php#photo-14164321"},{"acf_fc_layout":"image","image":{"ID":419922,"id":419922,"title":"eem_18_earthquakes134","filename":"eem_18_earthquakes134.jpg","filesize":27282,"url":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes134.jpg","link":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-living-atlas\/mapping\/the-cartography-of-time-magnitude-and-alert-levels\/eem_18_earthquakes134","alt":"Plain white bar.","author":"8492","description":"","caption":"","name":"eem_18_earthquakes134","status":"inherit","uploaded_to":392722,"date":"2019-01-24 22:25:41","modified":"2019-02-02 03:37:11","menu_order":0,"mime_type":"image\/jpeg","type":"image","subtype":"jpeg","icon":"https:\/\/www.esri.com\/arcgis-blog\/wp-includes\/images\/media\/default.png","width":3434,"height":233,"sizes":{"thumbnail":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes134-150x150.jpg","thumbnail-width":150,"thumbnail-height":150,"medium":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes134-300x20.jpg","medium-width":300,"medium-height":20,"medium_large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes134-768x52.jpg","medium_large-width":768,"medium_large-height":52,"large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes134-1024x69.jpg","large-width":1024,"large-height":69,"1536x1536":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes134.jpg","1536x1536-width":1536,"1536x1536-height":104,"2048x2048":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes134.jpg","2048x2048-width":2048,"2048x2048-height":139,"card_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes134-826x56.jpg","card_image-width":826,"card_image-height":56,"wide_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes134-1920x130.jpg","wide_image-width":1920,"wide_image-height":130}},"image_position":"center","orientation":"horizontal","hyperlink":""},{"acf_fc_layout":"image","image":{"ID":419542,"id":419542,"title":"eem_18_earthquakes127","filename":"eem_18_earthquakes127.jpg","filesize":52726,"url":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes127.jpg","link":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-living-atlas\/mapping\/the-cartography-of-time-magnitude-and-alert-levels\/eem_18_earthquakes127","alt":"Graphic with the words \"Cartographic Interpretation\".","author":"8492","description":"","caption":"","name":"eem_18_earthquakes127","status":"inherit","uploaded_to":392722,"date":"2019-01-24 20:23:53","modified":"2019-02-02 03:37:25","menu_order":0,"mime_type":"image\/jpeg","type":"image","subtype":"jpeg","icon":"https:\/\/www.esri.com\/arcgis-blog\/wp-includes\/images\/media\/default.png","width":680,"height":177,"sizes":{"thumbnail":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes127-150x150.jpg","thumbnail-width":150,"thumbnail-height":150,"medium":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes127-300x78.jpg","medium-width":300,"medium-height":78,"medium_large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes127.jpg","medium_large-width":680,"medium_large-height":177,"large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes127.jpg","large-width":680,"large-height":177,"1536x1536":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes127.jpg","1536x1536-width":680,"1536x1536-height":177,"2048x2048":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes127.jpg","2048x2048-width":680,"2048x2048-height":177,"card_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes127.jpg","card_image-width":680,"card_image-height":177,"wide_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes127.jpg","wide_image-width":680,"wide_image-height":177}},"image_position":"center","orientation":"horizontal","hyperlink":""},{"acf_fc_layout":"content","content":"

         <\/p>\n

        We already have three colors for time, using another four for red, orange, yellow, and green PAGER alerts would just be too many on the map. And why restrict yourself to that anyways?<\/em><\/p>\n

        At\u00a0first glance the color green implies “safe”, as well, the rainbow rank of the PAGER colors as a measure of potential damage do not immediately produce an intuitive visual hierarchy.<\/p>\n

        This is the cartographer’s craft – to envision the data in an authentic and meaningful way even if it goes against the data’s embedded and default colors. Stepping outside the box is sometimes necessary in order to try to intuitively convey the story of the data.<\/p>\n

        So instead of the PAGER alert colors, we can use the value of the colors we have already selected for time; and then, take those and ramp them from light to dark with three sequential colors thus demonstrating their severity.<\/p>\n

        This will be applied to the stroke or outline of the circle symbol. By applying a progressively thicker and darker stroke to our symbol this will convey something more significant or severe than for those symbols that only have a thin and light stroke.<\/p>\n

        Here are the symbol specifications:<\/p>\n

        Magnitude 4-4.9 = Size 12 points \/ Stroke 4 points
        \nMagnitude 5-5.9 = Size 18 points \/ Stroke 5 points
        \nMagnitude 6-6.9 = Size 24 points \/ Stroke 6 points
        \nMagnitude > 7 \u00a0= Size 30 points \/ Stroke 7 points<\/p>\n

        Here’s how these PAGER Alert Levels are arranged and what they mean:<\/p>\n

         <\/p>\n"},{"acf_fc_layout":"image","image":{"ID":423782,"id":423782,"title":"eem_18_earthquakes176","filename":"eem_18_earthquakes176.jpg","filesize":1079260,"url":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes176.jpg","link":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-living-atlas\/mapping\/the-cartography-of-time-magnitude-and-alert-levels\/eem_18_earthquakes176","alt":"Chart showing PAGER Alert Levels, Fatalities, and Estimated Losses.","author":"8492","description":"","caption":"","name":"eem_18_earthquakes176","status":"inherit","uploaded_to":392722,"date":"2019-01-29 19:26:20","modified":"2019-02-02 03:33:01","menu_order":0,"mime_type":"image\/jpeg","type":"image","subtype":"jpeg","icon":"https:\/\/www.esri.com\/arcgis-blog\/wp-includes\/images\/media\/default.png","width":4323,"height":3481,"sizes":{"thumbnail":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes176-150x150.jpg","thumbnail-width":150,"thumbnail-height":150,"medium":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes176-300x242.jpg","medium-width":300,"medium-height":242,"medium_large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes176-768x618.jpg","medium_large-width":768,"medium_large-height":618,"large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes176-1024x825.jpg","large-width":1024,"large-height":825,"1536x1536":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes176.jpg","1536x1536-width":1536,"1536x1536-height":1237,"2048x2048":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes176.jpg","2048x2048-width":2048,"2048x2048-height":1649,"card_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes176-577x465.jpg","card_image-width":577,"card_image-height":465,"wide_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes176-1341x1080.jpg","wide_image-width":1341,"wide_image-height":1080}},"image_position":"center","orientation":"horizontal","hyperlink":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2019\/01\/eem_18_earthquakes176.jpg"},{"acf_fc_layout":"content","content":"

         <\/p>\n

        Bertin writes that\u00a0value\u00a0<\/strong>variation\u00a0is ordered and represents a continuous progression, so much so, that you cannot disregard it visually (Bertin. 1983, p. 73).<\/em><\/p>\n

         <\/p>\n

        ArcGIS Online Symbology<\/h2>\n

        This web map was designed to use out of the box ArcGIS Online symbology so that it can be replicated by anyone within their own workflows. Please watch the video below to see the location of the circle symbol and how to apply the stroke.<\/p>\n

         <\/p>\n"},{"acf_fc_layout":"youtube","start_time":"0","end_time":"","youtube_video_url":"