Any videos of rock ground rupture of deep major faults?

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Discussion Overview

The discussion revolves around the possibility of capturing videos of ground ruptures along deep major faults during earthquakes, particularly focusing on instances where such ruptures occur in hard rock. Participants explore the challenges and conditions under which these phenomena might be filmed, as well as specific examples of fault behavior during seismic events.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants question whether any videos exist of deep faults reaching the surface in hard rock during coseismic motion, noting that most ground ruptures occur in softer soils.
  • One participant suggests that the physical rupture of hard rock would likely destroy camera equipment due to intense shaking, and that amateur photographers may not capture useful footage during such events.
  • Another participant emphasizes that deep-seated earthquakes, particularly those deeper than 30-50 km, typically do not rupture the surface, sharing personal experience in geology/seismology to support this claim.
  • Questions arise regarding the recent Sagaing Fault earthquake, specifically whether the surface rupture involved alluvial valley fills or if any rock outcrops were affected.
  • Discussion includes the behavior of hard rock during faulting, noting that previous fractures may be obscured by weathering and erosion, complicating the identification of fault lines at the surface.
  • One participant references a specific image mistaken for a fault expression, which is actually a landslide triggered by an earthquake, highlighting the complexity of interpreting geological features post-event.

Areas of Agreement / Disagreement

Participants express differing views on the occurrence of surface ruptures from deep faults, with some asserting that such events are rare or non-existent, while others seek specific examples or evidence. The discussion remains unresolved regarding the existence of videos capturing these phenomena.

Contextual Notes

Participants note that definitions of "deep faults" may vary, and the discussion includes assumptions about the depth of earthquakes and their potential to reach the surface. There is also mention of the limitations in capturing seismic events on video due to the nature of the phenomena.

snorkack
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TL;DR
Have any videos been captured of earthquake ground rupture in rock, along the main fault?
With recent abundance of security and cellphone cameras a lot of interesting and rare phenomena have been filmed.
There are many videos of local landslides and rockfalls.
Earthquakes commonly display shaking of buildings. Ground ruptures often happen in soft ground, in multiple places. Earthquake shaking may trigger rockfalls, along local faults unrelated to the main earthquake faults. Even when a ground rupture can be identified as the main earthquake fault, it is often in soft soil.
Have there been any occasions where a section of a deep fault reaching surface in hard rock has been filmed in coseismic motion?
 
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snorkack said:
Have there been any occasions where a section of a deep fault reaching surface in hard rock has been filmed in coseismic motion?
The release of energy by the physical rupture of hard rock nearby, will be sufficient to destroy the camera mountings. The camera will shake so much due to the broadband step displacement, that there will be no useful pictures.

Amateur photographers lack the discipline and presence of mind to hold a camera steady during an unexpected event, they panic, point the camera at the ground and run, just when they need to stand their ground to maintain the record.

Maybe, if there was a surveillance drone flying nearby, the camera would be sufficiently isolated, to capture the step change in ground position, along with the following oscillatory movements.
 
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snorkack said:
TL;DR Summary: Have any videos been captured of earthquake ground rupture in rock, along the main fault?

Have there been any occasions where a section of a deep fault reaching surface in hard rock has been filmed in coseismic motion?

The issue is, that deep seated quakes, even major ones, dont rupture the surface. That is, quakes deeper than around 30-50km.
In the 40 years I have been doing geology/seismology, I, personally, dont know of any quake deeper than around 15-25km that has ruptured the surface. .... If anyone has data on one that had, feel free to speak up 😊

So I guess you need to define your definition of "a deep fault"
A quake of 5 - 15km deep is a shallow crustal event.

cheers
Dave
 
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What was the recent Sagaing Fault earthquake like? It is said that over 500 km of the fault moved, displacement was up to 6 m and over long distances 4-5 m, and over long distances it was a surface rupture.
Was the surface rupture exclusively through alluvial valley fills through all these hundreds of km, or were any rock outcrops ruptured?
 
snorkack said:
Was the surface rupture exclusively through alluvial valley fills through all these hundreds of km, or were any rock outcrops ruptured?
When clamped by the hydrostatic pressure of the rock above, hard rock will shear cleanly. That evidence of faulting is seen in deep hard-rock mines, where differential weathering and erosion have not yet been applied.

Previous fractures, now exposed nearer the surface, will be selectively weathered and eroded by streams, hiding the expression of the fault zone, preventing the formation of a clear fracture line on the surface.

Future fractures, near the surface, will avoid solid blocks of hard rock that may be exposed, instead it will take a path of least resistance, through the weaker weathered zones, around those blocks.

At the surface, without the confining forces, the fault expression will be different. There will be thick slabs of solid rock, that slide, tilt and rotate, and there will be slumps and landslides, that will bury the observers with the evidence.

Take a look at the YouTube videos of landslides in Pakistan, India, and China, to see how the bigger surface blocks move, to hide the surface expression of the fault.
 
There is an image elsewhere on this forum, that appears at first sight to be the surface expression of an earthquake fault.
dlgoff said:
This image ... blows my mind:
It is actually the head, or sidewall, of a massive landslide, triggered by the nearby earthquake movement.
 

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