November 11, 1921—The keepers of Los Angeles Harbor
Lighthouse at the tip of the San Pedro Breakwater filed the following report with
the Superintendent of Lighthouses, San
Francisco:
I respectfully report a most unusual submarine disturbance
in the vicinity of this station yesterday. It began at 10 a.m. and continued to
recur at regular intervals through the afternoon and evening. The water of the
bay would become violently agitated and swirl around in a whirlpool for about
ten minutes, then suddenly slacken and run backwards slowly. At times there would
be a 7 to 8 knot current flowing underneath the lighthouse wharf. The steam
Daisy Matthews, inbound and lumber-laden, was seen to careen and be thrown off
her course and driven rapidly eastward when she poked her bow around the
breakwater. The battleship Arizona,
anchored at her berth 300 yards north of the station, make 8 or 10 complete
cycles during the afternoon and dragged anchor slightly. On her last turn, at 4
p.m., her stern was within 75 feet of the rocks at the base of the tower. She
was then removed to an anchorage near Long
Beach. A
shore boat came alongside the wharf and reported that the tide was running like
a millrace under the drawbridge in the Inner
Harbor, and there was an 8 knot
current at Deadman’s Island. The earthquake
theory has been suggested as accounting for this phenomenon.
Elinor's Note: The report was probably correct about the
earthquake. The Journal of Geophysical Research for December 1922 carried an
abstract for an article about the November 2011 earthquake in Australia that
probably caused the phenomenon at Los Angels Harbor Lighthouse:
There was a record of an earthquake on the magnetograms of
the Watheroo Magnetic Observatory, Western
Australia, on November 11, 1921. The declination and
horizontal-intensity traces showed a slight broadening, while there was a very
slight blurring of the vertical-intensity trace. The extreme Greenwich mean times of the record were from
18h 45m to 19h 0lm for declination,
18h 44m to 18h 56m for horizontal
intensity, and 18h 52m to 18h 59m
(uncertain) for vertical intensity. Mr. Curlewis, Government Astronomer at
Perth, reported the following times of phases as obtained on the seismograph:
18h 43m 56s.6, P; 18h 46m
00s.5, uncertain; 18h 50m 10s.4, L.
Earthquakes near or at sea create seismic energy waves that can travel long distances and cause tidal and wave fluctuations as they shoal up in harbors and their waves come on shore. These earthquake tsunamis can be huge, as we know from the tsunami in Japan several years ago. Today's Pacific Tsunami Warning System (established in 1946) warns of these events.
Los Angeles Harbor Lighthouse, nicknamed Angel's Gate Light, was built in 1913. It takes its share of pummeling from tremors and earthquakes and from storms and wind too. One storm caused the concrete platform on which it sits to sink on one side, giving the tower a slight list. The same storm slammed the tower with a wind gust that knocked one of the lightkeepers to the floor. The lighthouse was destaffed in 1971 and now operates automatically. It guards one of the largest shipping ports in the world at Long Beach. (Images courtesy of the U.S. Coast Guard.)
No comments:
Post a Comment
I welcome your comments, photos, stories, etc.!