System Update Log
A plain-language summary of significant changes as we improve Intensity Lab. Minor fixes and behind-the-scenes work aren't listed here.
- A simpler home page with three ways in: shaking videos worldwide, what we produce after a significant earthquake in our region, and simulated seismic waves crossing the region.
- New pages: After a significant earthquake, and Wave simulations.
- Peak ground velocity from our wave simulations. The regional movies now end on a map of the strongest ground velocity each place reached, a third movie shows that peak shaking spreading across the region, and the map appears on the event page. It uses the same measure as USGS ShakeMap (the larger horizontal component), so the two can be compared, though our simulations hold only waves below 0.5 Hz and read lower.
- Corrections to the About, account and legal pages. The regional summary email goes out when an earthquake in our region shakes a named place at five (V) or higher, not after every M3.5 event, and the site-specific report when shaking at your site reaches four (IV); the registration and account pages now say so. The coverage page now counts the 29 places in western Montana separately from Idaho.
- Privacy Policy updated (effective November 4, 2026): our YouTube animations are public videos, and no page shows other visitors' clip ratings, only your own result. The Disclaimer now lists the camera footage among our sources and notes that each clip is reviewed before it appears.
- Intensity levels in running text now read as words with numerals, for example four (IV).
- A globe on the homepage, and full screen at /explore/: every earthquake in the video collection and every magnitude 7 or larger since January 2026. Select an earthquake to see where its cameras stood, how far each was from the epicentre, and the intensity each clip shows. New magnitude 7 earthquakes appear on their own.
- The homepage now opens with what seismic intensity is, then the globe, then the three ways this site shows intensity: shaking videos, ground motion simulations and physics-based animations.
- The intensity scale page explains why the scale stops at X, with references.
- A new look: a lighter page header and footer, a new logo, one typeface throughout, and menus grouped as Intensity scale, Shaking videos, Earthquakes, Simulations and About. The intensity scale colours are now the only strong colours on the site, so colour always means intensity, and every page now keeps one light background.
- The intensity scale page now answers common questions: what the scale measures, how intensity differs from magnitude, how intensities are estimated, where damage begins, and why the scale here stops at X when the original runs to XII.
- Pages now describe themselves to search engines and link previews: each intensity level, earthquake and clip has its own title, summary and preview image.
- Rebuilt intensity scale pages. The scale overview has every level in one table, with sources. Each level page opens with a plain answer, then shows the clips rated at that level, our simulations of places that reached it, and recent earthquakes in the region that reached it, with answers to common questions such as what magnitude causes it.
- A new homepage: why intensity matters, the ten levels of the scale as a strip you can click, the 2019 Ridgecrest earthquake as a worked example of one earthquake with many intensities, the shaking video collection, and the latest earthquake in our region.
- Shaking videos are now arranged by intensity and by where each clip was filmed: homes, stores, public spaces, pools, trees, vehicles, warehouses, skyscrapers, and long-period motion far from large earthquakes. Each intensity level page can filter its clips the same way.
- New: Recorded vs. simulated. For California earthquakes with camera footage, each clip now plays beside the shaking we simulated for the same earthquake, at or near the place it was filmed. Play both together, switch between the Kitchen and Tabletop scenes, and see the reviewer's reading beside ShakeMap and the simulated values.
- New technical page: why a simulation can differ from what was filmed. It covers the earthquake source, the model of the crust, site effects, frequency content and the limits of one camera.
- Clip, comparison and event pages keep a bar at the top with the way back, and end with links to related pages.
- New: shaking videos. Camera footage of earthquakes around the world, each clip rated with the Modified Mercalli scale from the effects it shows: people running outdoors, goods falling from shelves, walls cracking. Browse the clips by intensity level, or watch a random one.
- Each clip lists the effects our reviewer saw, in the scale's own words, with links to what each level means. You can rate a clip yourself with a short interview and see the intensity your answers point to. No account is needed.
- The MMI scale pages now show clips filmed at each level beside our simulated animations, and the homepage shows a clip of the day.
- Every animation now says whether the shaking it shows was simulated or observed, on the video, on its ground-motion plot and data files, and on the site. Animations are named by where the shaking is (City, Station or Decay) and the scene that shows it (Tabletop or Kitchen).
- Station animations now run until the recorded shaking is mostly over. For large earthquakes they used to stop about ten seconds after the shaking arrived, before its strongest part.
- The home page now shows a map of the area we cover: the outlined region of the western United States and northern Mexico, with a dot for each of the 2,002 named places we estimate intensity for. A new Coverage & Data page, in the Learn menu, spells out which earthquakes are covered and why.
- The About menu now opens a list of short pages (Our Vision, Why Intensity Lab, History, Who We Are and Contact) in place of one long page. Our Vision moved here from the Learn menu, and what the site offers (formerly the Benefits page) is now part of Why Intensity Lab.
- Every shaking animation now comes with the ground motion behind it. Next to each video is a seismogram plot: the acceleration, velocity and displacement of the ground in three directions, with the part the animation shows shaded. A new Ground Motion Records section on each earthquake page has the plots full size, the peak values, and the data as downloadable text files, one each for acceleration, velocity and displacement, or all of them in one zip. Each file begins with a description of the earthquake, the site, where the motion came from (a simulation, a seismic station's recording, or a synthetic record) and how it was processed, so it makes sense on its own. Animations made before this change are being given records too; a few older ones cannot be, because the data they were drawn from was not kept.
- The home page now opens with recent seismic activity rather than a button pointing at it: a map of the events from the past 30 days, sized by magnitude and coloured by the strongest intensity estimated at any populated place, beside a list of the most recent few. Grey means an event has been detected but has no intensity report yet. The introduction above it is shorter.
- For a while you will also see reports and animations for smaller earthquakes than usual — magnitude 4.0 and above, rather than the magnitude 5.5-ish events that normally shake hard enough to produce them. This is deliberate and temporary. The full chain from detection through intensity estimates, email and animation to video is hard to check when qualifying earthquakes are months apart, so we are letting smaller ones through to confirm every step works.
- Two things to know while that lasts. You may get email about shaking you did not feel — a magnitude 4.0 is usually intensity III or below where people are, which is weak or unnoticed. And the simulated ground motion behind these animations is below the magnitude range the SCEC Broadband Platform is calibrated for, so treat those videos as a test of the system rather than a statement about the earthquake.
- There is now a page explaining how Intensity Lab uses the BBP simulation service, at Technical Information → How We Use the BBP Simulation API. It follows one earthquake through the whole exchange: what USGS supplies about the fault, how the cities and distance points are chosen, how the simulation method and crustal model are picked, what the request actually contains, how site stiffness (Vs30) is resolved, and what comes back — acceleration seismograms that are integrated twice to drive the animations. Two diagrams and no equations.
- Intensity Lab and BBP Services are now operating together. Intensity Lab reports what the shaking was at populated places and turns it into media people can watch; BBP Services runs the physics-based ground motion simulations behind those animations. Splitting them means each does one job properly: the consumer site is not carrying a simulation platform, and the simulation platform publishes its own verification evidence rather than asking you to take the animations on trust.
- Everything the site produces after an earthquake is now described in one place, with a live example of each: the population and seismic station intensity lists, the nearest site report, and the three kinds of animation.
- The site now states plainly who builds it, where every number comes from, and what it should not be relied on for, across a rewritten About page and a disclaimer covering data sources, editorial standards and corrections.
- Shaking animations can now be driven by physics-based simulated ground motion rather than motion synthesized from a peak value. This is what lets us show the shaking at a town with no seismometer in it, which is most towns.