Lightnews — Scholar-powered news

Theron Finley @theronfinley.bsky.social · Jul 23

This is fantastic news!

OpenTopography @opentopography.org · Jul 23

OpenTopography is excited to announce a major expansion to its international data catalog with the addition of the High Resolution Digital Elevation Model from Natural Resources Canada. This 1-meter resolution dataset is ideal for a wide range of applications.

opentopography.org/news/opentop...

Map showing extent of data coverage, primarily over southern Canada

A hillshade colored by elevation of downtown Toronto draped on Google Earth imagery.

A three panel figure of a section of the Athabasca River in Alberta. Figure A is the Digital Surface Model which includes buildings, trees and other structures. Figure B is the Digital Terrain Model and is a bare-earth representation of the topography. Figure C is the Canopy Height Model (CHM) which is the difference between the DSM and the DTM.

1 2

Reposted by Theron Finley

OpenTopography @opentopography.org · Jul 23

OpenTopography is excited to announce a major expansion to its international data catalog with the addition of the High Resolution Digital Elevation Model from Natural Resources Canada. This 1-meter resolution dataset is ideal for a wide range of applications.

opentopography.org/news/opentop...

10 12

Theron Finley @theronfinley.bsky.social · Jul 18

Thanks Britta! I’m headed up in two weeks and also can’t wait. The Yukon is truly the best!

1

Theron Finley @theronfinley.bsky.social · Jul 17

Glad you find it helpful, Jeff! Lots more work to do, now that we know this hazard exists.

1 2

Theron Finley @theronfinley.bsky.social · Jul 17

Indeed! I'm always amazed at the prescience of previous researchers, and it's great to be able to prove some of these hypotheses now that we have better data (ArcticDEM and lidar). Mortensen and Von Gaza speculated about these lineaments back in 1992(!) in an somewhat obscure YGS report!

1

Theron Finley @theronfinley.bsky.social · Jul 17

Certainly! The main point we were making here is that old, mature faults like this that were likely much more active in the past, and played a major role in the development of the Cordillera, still persist as crustal weaknesses and seismic hazards.

1

Theron Finley @theronfinley.bsky.social · Jul 17

Yes, the majority of the Canadian landmass, including BC, was covered by ice during the last glaciation. The southern ice limit was in the northernmost United States. Only northwest Yukon (and broader region extending across northern Alaska) remained ice free.

1

Theron Finley @theronfinley.bsky.social · Jul 17

Also, in the rest of Canada where the landscape is much younger, evidence of this sort of fault activity would be largely erased, highlighting a preservation problem in the paleoseismic record.

1 5

Theron Finley @theronfinley.bsky.social · Jul 17

More broadly these results highlight the seismic hazard of mature, low‐slip‐rate intraplate faults in orogenic belts, which may have very long recurrence intervals and elude detection via instrumental networks.

1 1 6

Theron Finley @theronfinley.bsky.social · Jul 17

For example, this figure from Bodtker et al (2022) shows the position of the Moosehide and Sunnydale landslides above Dawson City.

Satellite imagery map showing Dawson City, the location of the Moosehide Slide immediately of town, and the location of the Sunnydale landslide west of town across the Yukon River.

1 4

Theron Finley @theronfinley.bsky.social · Jul 17

A large rupture on the Tintina fault would cause significant shaking in the Klondike region, potentially damaging buildings, highways, and mining infrastructure. Compounding the hazard from seismic shaking, the region is prone to landslides, which could be seismically triggered.

1 1 5

Theron Finley @theronfinley.bsky.social · Jul 17

Notably, 12,000 year old landforms are not offset across the fault, which implies that it may be at a relatively late stage of an interseismic period, having accrued a slip deficit of ~6 m. From this, we estimate that ruptures of at least magnitude 7.5 are possible in the future.

1 2 6

Theron Finley @theronfinley.bsky.social · Jul 17

This figure from the paper shows 2.6 million year old glacial moraines offset across the fault, and a remarkable series of gravel mounds up to 35 m in height, that we interpret as push-up structures, developed over numerous seismic cycles.

Upper panel shows the Quaternary fault scarp evident in a hillshade map produced from ArcticDEM data. The scarp is expressed as a series of mounds and depressions, crossing a flat plain of gravel known to be 2.6 million years old. Glacial moraines and a terrace riser are shown to be offset right laterally by 500-1500 m. Lower left panel shows a 3D rendering of the push-up mounds developed along the fault. Lower right panel is a drone photo showing the dense boreal forest obscuring these features.

1 1 3

Theron Finley @theronfinley.bsky.social · Jul 17

What we see in the ArcticDEM data is 2.6 million year old glacial deposits offset right-laterally by ~1000 m, and 132,000 year old glacial deposits offset by ~75 m. These offsets imply numerous large earthquakes over the Quaternary period, and a slip rate of around 0.5 mm/yr.

1 3 6

Theron Finley @theronfinley.bsky.social · Jul 17

A really neat thing about the landscape in northern Yukon is that it was not ice covered during the most recent glaciation (24-12 ka), but ice was more extensive in two previous glaciations. The older landscape preserves a much longer tectono-geomorphic record than elsewhere in Canada.

2 2 6

Theron Finley @theronfinley.bsky.social · Jul 17

But, using the amazing ArcticDEM topographic dataset and drone-based lidar, we were able to map a ~130 km-long series of fault scarps near Dawson City, Yukon.

Topographic map of the study area in the Klondike region. Blue, yellow and pink polygons show the extent of three past glaciations, and a variety of data points show geochronological sample locations that constrain the timing of these glacial episodes. Red line shows the northwest-southeast trending, 130-km-long series of Quaternary fault scarps

1 2 5

Theron Finley @theronfinley.bsky.social · Jul 17

A thread on this paper! 🧪⚒️

The Tintina fault is a major right-lateral fault, stretching ~1000 km across the Yukon, and having slipped a total of ~430 km in its lifetime. It's generally thought to have been inactive since the Eocene.

Regional topographic map showing the location of the Tintina fault in the Yukon. Black dots show earthquake epicentres and blue arrows show GPS velocities recording crustal deformation. Blue, yellow and pink polygons show the extent of ice in three past glaciations. White box encompasses the study area in northern Yukon near Dawson City

2 5 16

Theron Finley @theronfinley.bsky.social · Jul 16

Really pleased to share our new paper in GRL, documenting evidence of multiple Quaternary surface-rupturing earthquakes on the Tintina fault in the Yukon.

doi.org/10.1029/2025...

@faultydata.bsky.social @earthquakeguy.bsky.social @thatfaultguy.bsky.social @tephrafan.bsky.social

Large Surface‐Rupturing Earthquakes and a >12 kyr, Open Interseismic Interval on the Tintina Fault, Yukon

We provide the first conclusive evidence of numerous large (>Mw 7.5) surface-rupturing earthquakes in the Quaternary on the Tintina fault Offsets to Early and Middle Pleistocene glaciofluvial ter...

doi.org

8 13

Theron Finley @theronfinley.bsky.social · Jun 12

Life update: got my PhD! What a journey. I'm especially grateful to my supervisors @faultydata.bsky.social and @earthquakeguy.bsky.social for their support and mentorship along the way. Also huge congrats to @thatfaultguy.bsky.social for graduating as well!

1 8

Theron Finley @theronfinley.bsky.social · Feb 22

Felt that one clearly at UVic, in the midst of typing the final few sentences of my thesis on mapping active faults in western Canada.

Ironically it’s the first I’ve felt around here since Nisqually 2001, when I was in grade 1. An education book-ended by earthquakes!

John Cassidy @earthquakeguy.bsky.social · Feb 21

That was a shallow M5.1 earthquake, 24 km NNE of Sechelt and 60 km NW of Vancouver at 1:26 p.m. PT. Shaking was felt by 1000's across southwest British Columbia.
Details/report shaking:
www.earthquakescanada.nrcan.gc.ca/recent/2025/...
⚒️🧪

Map showing the location of today's M5.1 earthquake located 60 km NW of Vancouver.

Seismograms showing shaking from today's M5.1 earthquake.

1

Theron Finley @theronfinley.bsky.social · Jan 11

SSA abstract submission deadline has been extended until Tuesday the 14th! If you work in the Alaskan and Canadian Cordillera, please consider submitting to our session:

Nick Harrichhausen @nharrichhausen.bsky.social · Dec 30

Attending the #SSA2025 meeting this year and working in the northern Cordillera and Alaska?

Consider submitting to our session (#33) "Neotectonics and Geohazards of the Interior Alaskan and Canadian Cordillera" !

meetings.seismosoc.org/wp-content/u...

meetings.seismosoc.org

Reposted by Theron Finley

Nick Harrichhausen @nharrichhausen.bsky.social · Dec 30

Attending the #SSA2025 meeting this year and working in the northern Cordillera and Alaska?

Consider submitting to our session (#33) "Neotectonics and Geohazards of the Interior Alaskan and Canadian Cordillera" !

meetings.seismosoc.org/wp-content/u...

meetings.seismosoc.org

1 4 4

Theron Finley @theronfinley.bsky.social · Dec 3

Wow, thanks Julie! @thatfaultguy.bsky.social deserves the largest credit for the drone lidar paper. We are glad to hear it is useful! Paper on the Tintina fault (with more drone lidar) is forthcoming!

Theron Finley @theronfinley.bsky.social · Dec 3

Thanks for the shout-out @seos-uvic.bsky.social! As far as I know, I don't have a publication in Nature Geoscience, but now I have goal to work towards :)

1 1

Theron Finley @theronfinley.bsky.social · Nov 14

If you work on active faults that are challenging to study due to low strain rates and/or environmental factors such as recently glaciated landscapes or dense vegetation, please consider participating in our session at SSA 2024, April 29-May 3, in Anchorage!

1