Natural History Museum & Earthquake

[Robert Lavenberg]

Status of the collections and condition of the Natural History Museum of Los
 Angeles County (LACM) as a result of the earthquake of January 17, 1994.

        The Natural History Museum of Los Angeles County suffered little collection
 damage resulting from the earthquake, but the building sustained some damage in
 the form of cracked walls throughout.
        Damage to the building and offices was more prevalent on the upper floors
 (third and fourth floors).  On the ground floor no collection damage occurred
 in holdings for ichthyology, herpetology, polycheates, crustacea-echinoderms,
 archeology-anthropology, or the molecular laboratory.  Most of these
 collections are maintained in Spacesaver compactors, and these installations
 served the collections well.  Many bottles were knocked down, but none broke
 and none were thrown from the carriages.  The tectonic braces served the
 carriages well.  Further, no damaged occurred in any of the ground floor
 offices.  The first floor serves for exhibits only, and no significant damaged
 occurred; some items in the various exhibits fell over or were displaced.
 Little damaged occurred.  Second floor serves exhibits, administrative offices,
 and collections, no damaged occurred in ornithology-mammalogy, but a few items
 were broken in the archeology-anthropology storerooms.  Some building damaged
 was noted between the administra
tive offices complex as they attached to the main building.  The third floor
 serves for offices, and the malacological, some echinoderm, entomological,
 botanical, and some historical collections.  Little collection damaged
 occurred, but many of the offices were trashed.  The fourth floor serves for
 exhibition and paleontological offices; paleontological collections are also
 stored on the fourth floor.  Although the heavy paleontological cases moved 6-7
 inches, no collection damaged was noted; however, the exhibits areas suffered
 moderate damage.  Some wall cabinets ripped from the wall on both the third and
 fourth floors.  Again, some fourth floor offices were trashed like those on the
 third floor.
        The old 1913 domed-building apparently suffered little damaged.  Data for the
 earthquake follows.

The San Fernando Valley Earthquake of January 17, 1994 of magnitude 6.6.
Data prepared as of 7:30 am, January 17, 1994.

        An earthquake struck the San Fernando Valley this morning at 4:30 am Pacific
 Standard Time.  As of 7:00 am, 15 aftershocks of magnitude 3.0 or larger have
 been recorded by the Southern California Seismographic Network.  The epicenter
 is located at 34! 13' north, 118! 33' west at a depth of 14.6 kilometers.  The
 surface wave magnitude from the National Earthquake Information Center is 6.6.
 The local magnitude is 6.4.
        The focal mechanism of the earthquake shows almost pure thrust (rake of 80!) on
 a fault striking 15! west of north with a dip to the north of 30!.  The
 location of the mainshock's epicenter is located several kilometers south of
 the southern end of the rupture zone.  Most of the aftershocks are located to
 the north of the mainshock around 10 kilometers depth.  At this point we have
 two competing hypothesis.  If the mainshock is on the north dipping place
 plane, it could be on the Elysian Park fold and thrust belt that produced the
 Whittier Narrows earthquake (magnitude 5.9) in 1987.  The aftershocks are then
 occurring because of sympathetic rerupturing of the 1971 zone.  The other
 possibility is that the mainshock occurred on the south dipping plane that is
 perhaps a backthrust of the main Elysian Park fault.

End of message
R. Lavenberg
Natural History Museum, Research and Collections, Section of Vertebrates
Voice 213 744-3446
FAX 213 748-4432
E-mail rlavenbe at usc.edu