[GK3]

I offer this article from NPR on the bombs we dropped and their damage. I always felt that the earth overlying the target would always limit the penetration of the bomb. Finally I found some discussion and actual math regarding this. Worth a read.
https://www.npr.org/2025/06/25/nx-s1-544...ear-target

If people didn't read this article, here are the highlights

When I ran the calculations, using a key equation from that study, I found out that the GBU-57 could go up to 80 meters (262 feet) underground if it was dropped in silty clay.

In medium-strength rock, things looked far different. The GBU-57 could only go around 7.9 meters (about 25 feet) beneath the earth — far short of the 60 meters claimed by the infographics.

Who would build their prize facility under silty clay?  Wikipedia indicates the Cheyenne Mountain Complex is 2000' under granite.

Per an ArcGIS map, Fordo and Natanz are in Tertiary Volcanics (But hey, I had real difficulty on a geology field trip identifying the large-grained, crumbling rock in Griffith Park (Los Angeles).  It was nothing like what we had back in Texas!)

What belief do we have in the claims of the penetration depth of this bomb?  We've taken the penetration depth at face value, but what is the basis of that claim?

(I'd think the propagation of the shock wave would be stronger in dense, solid rock, and weaker in weaker rock.  What is wanted is a strong shockwave at the ceiling of the chambers.  So maybe less penetration may not mean a weaker shock wave.)

Agreed.  I have forgotten the geologic terms given to the area around Fordo but it isn't granite and definitely not silty clay.  We built in Cheyenne mountain for obvious reasons.  The 2000 ft of granite rock is pretty tough to break through and the entrances are not easily hit either.  One reference I read said the area around Fordo was Limestone and Dolostone, whatever that is. Limestone is rock, but it isn't granite.  I have no clue how strong Dolostone is.

[GK3]

I offer this article from NPR on the bombs we dropped and their damage. I always felt that the earth overlying the target would always limit the penetration of the bomb. Finally I found some discussion and actual math regarding this. Worth a read.
https://www.npr.org/2025/06/25/nx-s1-544...ear-target

If people didn't read this article, here are the highlights

When I ran the calculations, using a key equation from that study, I found out that the GBU-57 could go up to 80 meters (262 feet) underground if it was dropped in silty clay.

In medium-strength rock, things looked far different. The GBU-57 could only go around 7.9 meters (about 25 feet) beneath the earth — far short of the 60 meters claimed by the infographics.

Who would build their prize facility under silty clay?  Wikipedia indicates the Cheyenne Mountain Complex is 2000' under granite.

Per an ArcGIS map, Fordo and Natanz are in Tertiary Volcanics (But hey, I had real difficulty on a geology field trip identifying the large-grained, crumbling rock in Griffith Park (Los Angeles).  It was nothing like what we had back in Texas!)

What belief do we have in the claims of the penetration depth of this bomb?  We've taken the penetration depth at face value, but what is the basis of that claim?

(I'd think the propagation of the shock wave would be stronger in dense, solid rock, and weaker in weaker rock.  What is wanted is a strong shockwave at the ceiling of the chambers.  So maybe less penetration may not mean a weaker shock wave.)

Agreed.  I have forgotten the geologic terms given to the area around Fordo but it isn't granite and definitely not silty clay.  We built in Cheyenne mountain for obvious reasons.  The 2000 ft of granite rock is pretty tough to break through and the entrances are not easily hit either.  One reference I read said the area around Fordo was Limestone and Dolostone, whatever that is. Limestone is rock, but it isn't granite.  I have no clue how strong Dolostone is.