I was sitting at the kitchen counter working on my laptop, tying up some loose ends after a busy work day. Then suddenly, bam! Then another, more forceful, BAM! All followed by a gentle rolling sensation. It was as if a large hand had slapped the side of the house and the solid ground it sits upon was now plate of jello.
I knew immediately it was an earthquake, a familiar feeling living in Southern California. I thought the temblor was close by, but where? What else could I learn about the earthquake and any impacts?
Make a quake map
ArcGIS Living Atlas of the World includes authoritative live feeds and other content that helps you learn more about earthquakes, faults, and what was experienced. Follow these steps to make your own earthquake map in a minute. The workflow is as follows:
- Make a map using the ArcGIS Living Atlas of the World Recent Earthquakes.
- Apply filters to display only the most recent quakes.
- Refine and finalize the map by changing the basemap and adjusting layer styles (optional).
Step 1 — Open Map Viewer, click Add, then Browse Living Atlas Layers.
Step 2 — Enter “earthquake” in search to locate the Recent Earthquakes layer. Click (+) to add it to the map.
Tip: To learn more about any layer, click the layer title to View item details.
From the Recent Earthquakes item details we learn that quakes are displayed by magnitude along with impact. 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.
The current map shows the magnitude (pun intended) of seismic activity in Southern California.
Explore the map and click features to learn more. The Events by Magnitude pop-up displays the magnitude, depth, date, time, PAGER alert status, and includes a link to the USGS event details.
The Shake Intensity pop-up displays the Mercalli Scale intensity and a description of what was felt and any expected damage.
Apply filters to find the latest quakes
The Recent Earthquakes layer shows events over the last 30 days. The next steps will for only the most recent temblors.
Step 3 — Open the layer filter.
Step 4 — 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 the quakes that have occurred in the last hour.
Other filters you can try are:
- Magnitude is greater than 4
- Event Time in the last 1 week
To sync the display of the layers, apply the same filter to both the Events by Magnitude and Shake Intensity layers. Note that some of the attributes will differ. Multiple filters and filter sets can be applied. For more information, see Apply filters.
Refine and finalize the map
World Topographic is the default basemap for our organization. This basemap seemed a little busy, competing with the Living Atlas Recent Earthquakes layer. A better map can be easily created with a few simple changes. See the before and after comparison below.
Recent Earthquakes is a feature layer, letting you apply your own styling to highlight what you want. A different basemap can be chosen to complement and highlight the layer. You can add other layers, such as fault lines, to provide additional context. The basemap can be adjusted by changing layer transparency and adding additional layers.
To create the final map on the right, the following adjustments were made:
- Recent Earthquakes layer style for magnitude 3 or less symbols was increased in size and changed to white (instead of gray) to provide more “pop.”
- Dark Gray Canvas basemap was used to replace the World Topographic basemap.
- Dark Gray Canvas Reference Layer, a sublayer in the basemap, was adjusted for 50% transparency so it would not compete with the earthquake locations.
- Earthquake Faults was added to the map from the Living Atlas, moved to the basemap layer group, and adjusted to 25% transparency.
- Terrain: Multi-Directional Hillshade Dark was added to the map from the Living Atlas, moved to the basemap layer group, and adjusted to 50% transparency.
The steps for making these adjustments are detailed in Help and in other blog articles. See the More information links in the section below.
For more information see:
- Browse Living Atlas layers
- Change style
- Create a multilayer basemap
- Configuring custom basemaps using Living Atlas layers
This article was originally published on Feb 24, 2018, and has been updated.