# Units and very large values in deq\_n100a15 (and meaning of ieq\_n100a15)

**URL:** <https://community.drivendata.org/t/units-and-very-large-values-in-deq-n100a15-and-meaning-of-ieq-n100a15/11557>\
**Category:** GEMS Prize Challenge\
**Created:** [October 7, 2026, 3:30pm UTC](https://community.drivendata.org/t/units-and-very-large-values-in-deq-n100a15-and-meaning-of-ieq-n100a15/11557 "2026-10-07T15:30:47Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Pablo\_Sicilia](https://avatars.discourse-cdn.com/v4/letter/p/c5a1d2/32.png) [@Pablo\_Sicilia](https://community.drivendata.org/u/Pablo_Sicilia)\
**Post date:** [October 7, 2026, 3:30pm UTC](https://community.drivendata.org/t/units-and-very-large-values-in-deq-n100a15-and-meaning-of-ieq-n100a15/11557/1 "2026-10-07T15:30:47Z")

</div>

Hi

While exploring the numerical features I found something I could not explain in the seismic bands, and I would appreciate a clarification.

Band deq\_n100a15 is described as “Distance to earthquake (n=100km radius, a=15° azimuth parameters)”. Inside the valid study area, its values are distributed like this:

- 1st percentile: 118
- median: 623
- 75th percentile: 1,685
- 99th percentile: 50,237
- 99.9th percentile: about 1.97 million
- maximum: about 4.96 million

So 99% of the pixels are below about 50,000, which would fit distances in metres within a 100 km radius. However, about 14,000 pixels (roughly 0.3% of the valid area) are above 500,000, and the maximum would be close to 5,000 km if read as metres, while the study area is roughly 330 x 373 km.

Could you clarify:

1. What is the unit of deq\_n100a15, and how is it computed? In particular, what do the n=100km and a=15° parameters mean?
2. Are the very large values expected (for example, a fill value for pixels with no earthquake within the radius), or could they be a data issue?
3. What does ieq\_n100a15 (“Earthquake intensity or density”) measure, and in what unit?

Thanks!!

---

<div class="post-metadata">

**Author:** ![chrisk-dd](https://avatars.discourse-cdn.com/v4/letter/c/b5ac83/32.png) [@chrisk-dd](https://community.drivendata.org/u/chrisk-dd)\
**Post date:** [October 7, 2026, 3:57pm UTC](https://community.drivendata.org/t/units-and-very-large-values-in-deq-n100a15-and-meaning-of-ieq-n100a15/11557/2 "2026-10-07T15:57:58Z")

</div>

Hi @Pablo_Sicilia -

Those bands are the INGENIOUS earthquake rate density layers that have been clipped to the GeoDAWN area and re-gridded to 100m. For more detailed information, you can look at the original dataset on the [INGENIOUS site](https://gdr.openei.org/submissions/1391) (download “Earthquake Density Models.zip”, extract it, then look at eq\_rate\_density\_details.docx).

-Chris