ArcGIS Online

Earthquake impact analysis using ArcGIS Online and ArcGIS Living Atlas

In this simple exercise you will determine the total population that is within proximity of an earthquake with measured shake intensity. The analysis will be performed using ArcGIS Online tools with ArcGIS Living Atlas content. Note that appropriate privileges are required to use analysis tools to complete the exercise. The workflow is:

 

Make a map of recent earthquakes

Step 1 — Go to the Living Atlas website and sign in using your ArcGIS organizational account.

Sign in

Step 2 — Open the Browse tab and enter “recent earthquakes” in search.

Search

Step 3 — Locate the Recent Earthquakes feature layer and click the thumbnail or title to open the item details.

Recent Earthquakes feature layer

From the Recent Earthquakes item details we learn that quakes are displayed by magnitude along with impact information. Events are updated as frequently as every 5 minutes and are available up to 30 days, except for events of magnitude less than 3.0 (retained 3 days) and events of magnitude less than 4.5 (retained 7 days). Labeled quakes are those with a PAGER alert, a measure of the scope and impact of the event.

Step 4 — Open the layer in a new map. Save the map for future use.

Open in Map Viewer

 

Locate a quake event for analysis

Step 5 — Explore the map to find an area of interest. As you explore the map, click features to learn more about them.

The Events by Magnitude layer pop-up displays the magnitude, depth, date, time, PAGER alert status, and includes a link to the USGS event details.

Pop-up information

The Shake Intensity layer pop-up displays the Mercalli Scale intensity and a description of what was felt and any expected damage.

Pop-up information

At the time of writing this article, a quake near Perry, Oklahoma, was chosen for the analysis.

Earthquake event

 

Filter shake intensity

Apply a filter to the Shake Intensity layer to show areas with an intensity of 4 or greater, eliminating the lesser intensities where the quake is less likely to have been felt or cause damage.

Earthquake intensity

Step 6 — Open the Shake Intensity layer filter.

Quake Intensity filter

Step 7 — Create a filter expression.

Expressions use the general form of <Field_name> <Operator> <Value, Field or Unique>. Use the dropdown menus to create the desired filter, in this case Intensity value is at least 4. When finished, apply the filter.

Filter expression

 

Dissolve the boundaries

Step 8 — Since there may be overlapping or disconnected polygons matching the expression, dissolve the layer to create a single, multi-part polygon for additional analysis.

a — Click Analysis.

b — Open the Manage Data group.

c — Select Dissolve Boundaries.

Dissolve analysis tool

Step 9 — Enter the Dissolve Boundaries tool parameters.

a — Select the Shake Intensity layer.

b — Accept the defaults to create multi-part features.

c — Enter the layer name for the result.

d — Ensure that you have zoomed to the extent of the earthquake of interest and check Use current map extent. Since we are not interested in other earthquakes, this limits the analysis to this particular event and minimizes credit consumption for the analysis.

e — Click Run Analysis to perform the analysis.

Dissolve analysis tool

The result of Dissolve Boundaries is a single layer with a single multi-part polygon. Click the polygon to view the aggregated area.

Dissolve analysis result

This new layer can be used for further analysis. In the next steps, the layer will be enriched to determine the number of people that experienced an intensity level of 4 or greater.

Step 10 — Enrich the layer.

a — Click Analysis.

b — Open the Data Enrichment group.

c — Select Enrich Layer.

Enrich Layer tool

Step 11 — Enter the Enrich Layer parameters.

a — Select the dissolved Shake Intensity layer from Step 8.

b — Click Select Variables.

Enrich Layer

This opens the Enrich Layer Data Browser.

c — Select the Population data category.

Population data category

Next, choose the variables that you want to apply.

d — Check 2020 Total Population.

e — Click Apply.

Choose variables

Complete other Enrich Layer parameters by entering the following:

f — Output layer name.

g — Use the current map extent, since we only want to apply the analysis to the current polygon.

h — Click Run Analysis to apply the selections.

Enrich Layer analysis

The enriched polygon now includes 2020 population counts. The image below shows a configured pop-up for the result showing the size in square miles and the 2020 total population within the polygon.

Enriched polygon

 

More information

For more information, see the following:

 

This article was originally published on February 15, 2018, and has been updated.

About the author

Tech evangelist and product manager at Esri, focusing on ways to broaden access to geographic information and helping users succeed with the ArcGIS Platform. On a good day I'm making a map, on a great day I'm on one. Follow @bernszukalski or email bszukalski@esri.com

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