Frequently Asked Questions

What is the Unified Hazard Tool (UHT)?
How long will the UHT be supported?
Will the URL of the tool change?
What are the strengths and limitations of the UHT?
Where are the earthquake rate, deaggregation, and other tools now?
Why were the existing tools retired?
Are the web-services underlying the UHT documented and available for use?
I have a question or suggestion; how can I provide feedback?
Are time dependent models supported?
How are UCERF3 deaggregations handled?

What is the Unified Hazard Tool (UHT)?

The Unified Hazard Tool provides a single, streamlined interface for accessing various USGS National Seismic Hazard Models and data and analyses derived therefrom. One may use the UHT to obtain probabilistic hazard curves, as well as earthquake rate and probability data. The UHT replaces a suite of independent tools formerly available on the USGS website. For

How long will the UHT be supported?

Indefinitely.

Will the URL of the tool change?

Not anytime soon. If and when it does, a redirect will be used. We apologize that this was not done when retiring our legacy tool set.

What are the strengths and limitations of the UHT?

TODO

Where are the earthquake rate, deaggregation, and other tools now?

TODO

Why were the existing tools retired?

TODO

Are the web-services underlying the UHT documented and available for use?

TODO

I have a question or suggestion; how can I provide feedback?

TODO

Are time-dependent models supported?

All USGS models and data provided by the UHT are time-independent. This may change in the future.

How are UCERF3 deaggregations handled?

UCERF3 is the California component of the 2014 USGS National Seismic hazard Model (NSHM). It relaxes fault segmentation, allowing for "multi-fault ruptures", and therefore provides rates for hundreds-of-thousands of possible rupture geometries within the California fault network, where all named, mapped, 'parent' faults have been discretized into ~7 km long sections. When deaggregating, the list of contributing sources to hazard at a site is very long with no individual rupture or ruptures contributing significantly to the total hazard. To address this, the deaggregation service behind the UHT aggregates contributions on a per-fault-section basis, with rupture contributions only ever counted once. The UHT deaggregation contributor list shows those sections, identified by a 'parent' fault name and section index, which contribute most to hazard at a site. Under the hood, the total contribution of a section is also decomposed by magnitude, however we do not report these value at this time, just the mean magnitude for the section.