 |
| The rugged,
subtropical terrain of the Coastal Range is bisected
by the Hsiukuluan River as it flows away from the
central spine of the island and out into the Pacific
Ocean. The grey mudrocks and conglomerates of the
range are young (Pliocene) and weak, and are cut
easily by the powerful Hsiukuluan. The densely forested
hill slopes are steep and heavily prone to landslides
as they are undercut by the meandering channels.
The unusual rates of erosion portrayed here are emblematic
of the geomorphology of Taiwan. Photo by Colin P.
Stark. Click
here for slide show of more photos. |
Results from one of the most comprehensive studies of erosion
of the earth's surface have revealed the detailed spatial
pattern of erosion in the Taiwan mountain belt. The findings,
recently reported in NATURE, provide evidence that mountain
erosion can be directly related to large earthquakes and
storms. Taiwan is one of the most rapidly eroding mountain
belts on earth, with average erosion rates of 3-6 mm per
year and extreme rates of 60 mm per year in some areas
of weak rock that have recently experienced large earthquakes
and storms.
An international team of scientists
from Cambridge University's Department of Earth Sciences,
the National Taiwan University, the University of Washington,
and Lamont-Doherty Earth Observatory of Columbia University
in the USA, are attempting to understand erosion of tectonically
active mountain belts. This study will help explain the
links between tectonics, climate, and erosion, and will
provide vital information to combat natural hazards such
as landslides, floods, and earthquakes.
The new results show that on time-scales
of millions of years, erosion rates in the Taiwan mountains
balance the upward movement of the earth's crust. Between
1970 and 1998, erosion rates were highest in areas where
large earthquakes and storms had occurred. These results
pave the way for future investigations into the detailed
impact of individual earthquakes and storms like the
1999 Mw 7.6 Chi-Chi earthquake and the recent typhoons
Bilis and Toraji, which altogether claimed 3,800 lives
and cost 15 billion US dollars.
To view a slide show illustrating
the erosion of the Taiwanese landscape, click
here. These photographs, including the one at right,
were taken by Colin P. Stark during two field seasons
in Taiwan in September 2002 and January 2003, the latter
around the time of a major GSA Penrose conference on
tectonics, climate and erosion held in Taroko National
Park.
To read the paper in Nature, visit: http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v426/n6967/full/nature02150_fs.html
|
