Effects of the Impact 65 mya

[Richard W Travsky <rtravsky@uwyo.edu>]

>From the upcoming issue of Science News


The extraterrestrial object suspected to have splashed down near Mexico's
Yucatn peninsula more than 65 million years ago did more than just blast a
big hole, cause worldwide climate change, and wipe out the dinosaurs. In
the short term, seismic vibrations triggered massive underwater landslides
and tsunamis far up the eastern coast of North America (SN: 12/9/00, p.
373:  http://www.sciencenews.org/20001209/fob4.asp). Now, scientists say
they've identified enormous earth movements from the same era along the
Pacific Coast.

When the chunk of asteroid or comet struck, it generated an earthquake
that probably would have registered about magnitude 13. Even as far as
7,000 kilometers from ground zero, spreading seismic ripples would have
heaved the ground up and down as much as 1 meter, says Grant Yip, a
geologist at the University of California, Santa Barbara. He and his
colleagues contend that the thick layers of jumbled sediments now exposed
by erosion in a canyon in northern Baja California record a series of
gigantic landslides that stemmed from the impact. 
...
The landslide debris that Yip and his colleagues studied is clearly of the
same age as the Yucatn impact, says John V. Firth, a geologist at Texas
A&M University in College Station. However, he notes, strong earthquakes
that could trigger immense landslides are common in Baja California. Other
examples from the same area and era would strengthen the case that the
landslides were triggered by the distant extraterrestrial impact and not
by local events. 

Busby, C.J., G. Yip, et al. 2002. Coastal landsliding and catastrophic
sedimentation triggered by Cretaceous-Tertiary bolide impact: A Pacific
margin example? Geology 30(Aug.):687-690.

http://www.gsajournals.org/gsaonline/?request=get-abstract&issn=0091-7613&volume=030&issue=08&page=0687