Explore layers and data

Scientists and governments around the world closely monitor natural disasters like earthquakes and volcanoes. Even if these hazards don’t occur within a country’s borders, they can still have ripple effects that impact that country. For example, earthquakes can trigger tsunamis that travel across the ocean and hit faraway beaches. To monitor these threats, scientists use maps. In this tutorial, you'll add, remove, and adjust map layers showing earthquake and volcano hazards in MapMaker.

In this tutorial you will learn to:

• Add layers to a map
• Show and hide layers from the map
• Adjust the transparency of layers
• Reorder layers on the map
• Open and use a data table from a layer
• Remove layers from the map

This tutorial was last tested on September 10, 2024.

Requirements

Explore layers and data

Explore a map layer

First, you'll open a map that contains data on major earthquakes and volcanic eruptions. Each map layer in MapMaker includes a description that provides additional information about the topic of the data, information about the data source, and any decisions made by the cartographer that would impact the understanding of the map. You'll explore the map to familiarize yourself with the layers.

1. Open the Plate Tectonics map.

   

2. On the toolbar at the bottom of the screen, click the Map layers button.

   

   The Map layers pane appears. This pane lists all the data layers within the map and has tools for working with them.

   By default, the map shows the Earthquakes (Major) layer. You can change what layers are shown on the map by turning them off and on.

3. For Volcanic Eruptions (Significant), click Toggle visibility to turn the layer on.

   

   The map redraws to show the Volcanic Eruptions (Significant) and the Earthquakes (Major) layers. Each map layer represents a specific theme of geographic data.

4. For the Volcanic Eruptions (Significant) layer, click the Show legend button to open the layer legend.

   

   The Volcanic Eruptions (Significant) map layer shows eruptions as points in different colors based on their status on NOAA's Volcanic Explosivity Index. A single volcano may have more than one point that represents different eruptions.

5. For the Volcanic Eruptions (Significant) layer, click the Description button to open the layer description.

   

   Each map layer includes a description that provides additional information about the topic, the data, and any decisions made by the cartographer.

6. Click the Description button again to hide the text.

Change how a layer appears on the map

Many maps show multiple layers to help people compare information. In the case of this map, you want to understand where both earthquakes and volcanos occur. There are many ways to make sure all layers are visible on the map. Next, you'll adjust map layers in MapMaker by changing the transparency, the order in which the layers appear, and the scale. You'll also explore the data further with the swipe tool.

1. On the Map layers pane, for the Volcanic Eruptions (Significant) layer, click the Adjust transparency button.

   

   A slider appears. Moving the slider to the left makes the map layer less opaque. Changing the transparency of a map layer allows you to see the basemap or other features under the layer, which can add context to the map.

2. Use the slider to change the transparency of Volcanic Eruptions (Significant) to about 50 percent.

   

   Note:

   You can set the transparency of multiple layers at a time.

3. Click the Swipe button.

   

   A vertical bar is added to your map. On the left side of the map, you can see the eruption points, but on the right side, they are hidden. With the swipe tool, you can compare data from two different time periods to see how things have changed, see similarities or differences in patterns, or temporarily remove data from part of a busy map to see a feature at a lower level.

4. Click the bar and drag it back and forth to explore the data.

   

5. On the Map layers pane, for the Earthquakes (Major) layer, click the button to the left of the title and drag it above Volcanic Eruptions (Significant).

   

   The earthquake points now appear on top of the eruption points on the map.

   Note:

   Moving some layers up the list could obscure other data.

6. For the Volcanic Eruptions (Significant) layer, click Swipe to turn off the swipe tool.
7. In the Map layers pane, click Toggle visibility to turn on the Latitudes and Longitudes layer.
8. In the upper left corner of the map, use the Zoom in button to zoom in to Hawaii.

   

   The data on this map is scale dependent, meaning that it changes with scale. As you zoom in, the lines of latitude and longitude change with the map scale. In some cases, data may completely disappear once you reach a specific scale.

Use a data table

Next, you'll explore earthquake data in a table. Geospatial data can be as simple as the latitude and longitude of a particular point of interest. In addition to location information, geospatial data can also contain other information about a place. For example, the volcano layer contains the location of the volcano as well as its name, the type of volcano it is, its Volcanic Explosivity Index, and more. You can ask questions of the data by searching or filtering it to tell a specific story. For example, you can sort the Earthquake data to learn more about the highest magnitude earthquakes that have been recorded.

1. In the upper left corner of the map, click the Default map view button.

   

2. On the Map layers pane, expand the Earthquakes (Major) layer and click the Table button.

   

   The data table appears at the bottom of the window. The top of the table lists the layer name and the total number of features it includes. The Earthquakes (Major) layer has 949 major earthquakes recorded.

3. In the header of the table, click Date and Time to sort the column.

   

   Note:

   You can also sort columns by clicking Options in the column header you wish to sort, then choosing Sort ascending or Sort descending.

4. On the left side of the table, check the box to select the earliest earthquake recorded in this dataset.

   

   When you check a box in the data table, the feature is selected. The selected record in the data table is highlighted in blue and the corresponding earthquake is highlighted on the map. You can zoom to the location of selected features on the map.

5. On the table ribbon, click the options button and choose Zoom to selection.

   

6. On the Map layers pane, click the Table button to close the table.
7. Click the Toggle visibility button for the Latitudes and Longitudes and Volcanic Eruptions (Significant) layers to turn them off.

Add a layer

Next, you'll add another layer to the map.

1. On the toolbar at the bottom of the screen, click the Add layer button.

   

2. In the Add layer pane, in the search bar, type Cities of the World.
3. For the Cities of the World layer, click the Add button to add the layer to your map.

   

   The Cities of the World layer is added to the map.

4. Close the Add layer pane.
5. On the toolbar at the bottom of the screen, click the Map layers button. For the Cities of the World layer, click Legend.

   

   The largest circles on the map represent cities with the largest population as of 2015. Earthquakes can cause significant damage, especially in densely populated cities. Tokyo, Japan, one of the world's largest cities, is located near the famous Ring of Fire. It experiences nearly 1,500 earthquakes each year.

6. In the upper left corner of the map, click the Open search button. For Find address or place, type Japan and press Enter.

   What other large cities are near major earthquakes?

Remove a layer

Next, you'll remove layers from the map that you no longer need. While adding data to the map, like the Cities of the World layer, can help you identify new patterns in the data, it can also cause the map to get cluttered. When too many layers are on the map, it can make your data harder to understand.

1. On the Map layers pane, scroll to the Volcanic Eruptions (Significant) layer. Click the Remove button.

   

   The layer is removed from the map.

In this tutorial, you learned how to explore data and layers in MapMaker. You turned layers on and off, changed their transparency, and opened their tables for more information. You also used the swipe tool to compare different layers. Then, you added a layer and removed another layer.

You can find more tutorials in the tutorial gallery.

Acknowledgements

• Earthquakes (Major): United States Geological Survey / Earthquake Catalog.
• Volcanic Eruptions (Significant): National Geophysical Data Center / World Data Service (NGDC/WDS): NCEI/WDS Global Significant Volcanic Eruptions Database. NOAA National Centers for Environmental Information. doi:10.7289/V5JW8BSH.
• Plate Boundaries: Peter Bird, Hugo Ahlenius/Nordpil.
• Cities of the World: United Nations, Department of Economic and Social Affairs, Population Division (2018). World Urbanization Prospects: The 2018 Revision, Online Edition.
• Ethnicity: Esri, United States Census Bureau.
• Imagery Hybrid map sources: Esri, HERE, Garmin, FAO, NOAA, USGS, OpenStreetMap contributors, and the GIS User Community