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Details for Benchmark: HT2630

N 37° 31.569 W 122° 06.095 (NAD 83)

Altitude: 327

Coordinates may not be exact. Altitude is VERTCON and location is ADJUSTED. (more info)

Location:
In ALAMEDA county, CA View Original Datasheet
Designation:
SAN FRANCISCO RAD STA KGO MAST
Marker Type:
navigation light
Setting:
setting not listed - see description
Stability:

Must Read!

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As I mentioned earlier, this station was destroyed in the 1989 Loma Prieta earthquake. The KGO towers that people have seen since then are replacements, so they are not HT2630.

The NGS has now officially declared HT2630 destroyed. You can see the updated datasheet on the [url=http://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=HT2630]NGS website[/url].

Seen from Dumbarton Express Bus

HT2360 is a good object lesson on how confusing intersection stations can be. You see a radio tower or a church steeple or a water tower and you think, "Aha--the survey station is still there!" But it usually takes some research to confirm that, unless you're already familiar with the history of the station for its entire life.

In this case, all three KGO towers were damaged during the 1989 Loma Prieta earthquake and had to be replaced. So none of the towers seen today--including the center tower mentioned in the description of HT2360--were the ones in existence at the time this station was created.

I'm attaching a photo taken by the USGS of the damaged towers.

[Photos:]
photoKGO towers after Loma Prieta earthquake

Rather an easy find I must say.

[Photos:]
photoKGO Masts
Rightmost mast
photoKGO Masts
Rightmost mast

Documented History (by the NGS)

01/01/1982 by USCG (FIRST OBSERVED)
DESCRIBED BY US COAST GUARD 1982 (MEF) THE STATION IS KGO RADIO STATION CENTER MAST AND IT IS LOCATED IN THE TOWN OF FREMONT, IN A SALT POND ABOUT 3.2 MILES WEST OF THE CITY OF NEWARK, 1.2 MILES SOUTHWEST OF COYOTE HILLS AND 1.0 MILE NORTHEAST OF DUMBARTON BRIDGE. THE STATION IS RED LIGHT ATOP A 323 FEET RADIO MAST, IT IS THE CENTER MAST OF THE THREE. DESCRIBED BY QMCS M.E. FRIAS

Control Text

  • The horizontal coordinates were established by classical geodetic methods and adjusted by the National Geodetic Survey in March 1994. The horizontal coordinates are valid at the epoch date displayed above. The epoch date for horizontal control is a decimal equivalence of Year/Month/Day.
  • The NAVD 88 height was computed by applying the VERTCON shift value to the NGVD 29 height (displayed under SUPERSEDED SURVEY CONTROL.)
  • The Laplace correction was computed from DEFLEC99 derived deflections.
  • The geoid height was determined by GEOID99.

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