Vega Visualization Grammer and Geofon: Visualising Earthquakes

Changelog

Demo

Find here all earthquakes reported by GFZ (Helmholtz Centre for Geosciences) for today (limited to the 40 most recent ones) visualized using the Vega Visualization Grammar.

Description

This is a demonstration how to use the Vega Visualisation Grammar with a complex visualization and a data source from the web (Earthquakes by GFZ).
We show the most 40 recent earthquakes in the world reported by GFZ when the user opens the web page.

Technical Aspects

This is a static web page and it is self-contained, ie it hosts all the scripts and stylesheets. We do NOT load the Vega library from a Content Delivery Network (CDN) as this is not under our control and insecure (despite being recommended on the Vega web page). See, for example, here.

We use Content Security Policies to secure the page against cross-site scripting attacks. You will need to include vega-interpreter for this. However, in the current version of the page we must still allow "unsafe-eval" for script-src, because vega-interpreter does not seem to support all functions (see bug report).

We used the Vega online editor to develop the visualisation. You can find the JSON spec here. It is based on this Vega example. We load in the spec the 40 most recent earthquakes using the following source: https://geofon.gfz.de/fdsnws/event/1/query?limit=40&format=text

You can find the full code of this web page here: https://codeberg.org/jornfranke/demo-web-pages/src/branch/pages/vega-gfz-earthquakes/