Once a year, on December 7th, the Mt. Diablo beacon is lit and shines over a wide area from around sunset until around sunrise the next day.
According to the organization “Save Mount Diablo”:
“Standard Oil of California constructed a 75 ft aviation beacon jointly with the U.S. Dept of Commerce to encourage and as a guide for commercial aviation (visible for 100 miles, first lit by Charles Lindberg). The beacon was later transferred to the Summit Building and is now lit only on December 7th, Pearl Harbor Day.”
The Summit building was built by the Civilian Conservation Corps between 1939 and 1942.
The beacon was used until December 7, 1941. With the attack on Pearl Harbor, the beacon was turned off so as to not guide Japanese planes for night attacks. After the war it was no longer needed, and fell into disrepair. The beacon was repaired in 1964 by Pearl Harbor survivors. That year also began the Memorial Ceremony and lighting of the beacon each December 7th.
The Mt. Diablo chapter of the Pearl Harbor Survivors Association holds a memorial ceremony in the summit building each year. The service consists of a guest speaker, and each of the survivors speaks of his experience. This year the speaker was Major General Ronald Lowe, who was deputy commander chief of staff of the U.S. Pacific Command in Hawaii from 2000 to 2004. There were 3 survivors in attendance, at least one for the first time this year. Several had passed away this past year.
The public may attend this ceremony, although the space inside the summit museum is limited, mainly to the survivors, their families, and a few others. Speakers are set up outside for others to hear. The ceremony began at 3:45pm this year. A shuttle bus was provided to bring people back and forth from the lower parking lot, but most people, including me just hiked. It is about a fifth of a mile, but a 140 foot elevation change. There is very limited parking at the summit itself.
The 2010 Ceremony consisted of:
Posting of Colors and Pledge of Allegiance: Military History Preservation Society
Welcoming Remarks - Roland Gaebert, Superintendent, Mt. Diablo State Park
Ceremonial Remarks - Major General Ronald Lowe, United States Army, Retired
Introduction of Pearl Harbor Survivors and Their Reminiscences of "That Morning"
Commemorative Comments - Ron Brown, Executive Director, Save Mount Diablo
"Taps" - Frank Dorritie, Member of Bugles Across America
Lighting of the Pearl Harbor Remembrance Beacon - Pearl Harbor Survivors - Parking Lot
The Pearl Harbor Survivors in attendance this year were:
 John Tait - U.S.S. St. Louis |
 John Egan - U.S.S. San Francisco (CA-38) |
 Hank Fries - U.S.S. Detroit |
The beacon can easily be seen from my house in south-west Livermore, about 16.5 miles away. I first noticed it 2009. While lying in bed, I was seeing a beacon flash and could not figure out what it was. I thought it might be from the Livermore Airport beacon, about 2.6 miles away and in a similar direction, but I had never directly seen that beacon before from the house. I had only seen the beam in the fog when weather conditions are just right. After seeing it for hours, I got up in the morning and realized that the beacon was coming from a much higher altitude, and that it would likely be Mt. Diablo. An internet search then let me know why it was on.
In 2010 I traveled to Mt. Diablo for the Ceremony with cameras in hand. The photos from that trip are contained here. I again saw the beacon all night long, even though it was getting cloudy. It was strong enough that I could even notice it with my eyes closed. It was the quick flash as it spun by was noticeable in this case.
In the morning, about 5:30am, I took some photos from my back yard. It was raining at the time, but the beacon was still quite visible. Fortunately I have an overhang to protect me, and more importantly my camera, from the rain. I used a 2 second exposure and timed it so that I would catch the light coming by.
The beacon flashes about once every 9.5 seconds.
 The beacon before the ceremony. It is aiming toward my house in Livermore I do not know why the tires are there. |
 The 2nd story entrance to the museum |
 Livermore, from the Mt. Diablo Summit. After all, this is eLivermore.com |
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 Making sure the beacon will spin. He pushed it for several revolutions. There were lots of jokes about him getting tired by morning. |
 The bulb can be seen between the two upper bars. |
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All photos by Bill Nale of eLivermore.com