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| Titel |
Submarine landslides in the Santa Barbara Channel as potential tsunami sources |
| VerfasserIn |
H. G. Greene, L. Y. Murai, P. Watts, N. A. Maher, M. A. Fisher, C. E. Paull, P. Eichhubl |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 6, no. 1 ; Nr. 6, no. 1 (2006-01-16), S.63-88 |
| Datensatznummer |
250003282
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| Publikation (Nr.) |
 copernicus.org/nhess-6-63-2006.pdf |
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| Zusammenfassung |
| Recent investigations using the Monterey Bay Aquarium
Research Institutes (MBARI) Remotely Operated Vehicles (ROVs) "Ventana" and "Tiburon" and
interpretation of MBARI's EM 300 30 kHz multibeam bathymetric data show that
the northern flank of the Santa Barbara Basin has experienced massive slope
failures. Of particular concern is the large (130 km2) Goleta landslide
complex located off Coal Oil Point near the town of Goleta, that
measures 14.6-km long extending from a depth of 90 m to nearly 574 m deep and
is 10.5 km wide. We estimate that approximately 1.75 km3 has been
displaced by this slide during the Holocene. This feature is a complex
compound submarine landslide that contains both surfical slump blocks and
mud flows in three distinct segments. Each segment is composed of a distinct
head scarp, down-dropped head block and a slide debris lobe. The debris
lobes exhibit hummocky topography in the central areas that appear to result
from compression during down slope movement. The toes of the western and
eastern lobes are well defined in the multibeam image, whereas the toe of
the central lobe is less distinct. Continuous seismic reflection profiles
show that many buried slide debris lobes exist and comparison of the
deformed reflectors with ODP Drill Site 149, Hole 893 suggest that at least
200 000 years of failure have occurred in the area (Fisher et al., 2005a).
Based on our interpretation of the multibeam bathymetry and seismic
reflection profiles we modeled the potential tsunami that may have been
produced from one of the three surfical lobes of the Goleta slide. This
model shows that a 10 m high wave could have run ashore along the cliffs of
the Goleta shoreline.
Several other smaller (2 km2 and 4 km2) slides are located on the
northern flank of the Santa Barbara Basin, both to the west and east of
Goleta slide and on the Conception fan along the western flank of the basin.
One slide, named the Gaviota slide, is 3.8 km2, 2.6 km long and 1.7 km
wide. A distinct narrow scar extends from near the eastern head wall of this
slide for over 2km eastward toward the Goleta slide and may represent
either an incipient failure or a remnant of a previous failure. Push cores
collected within the main head scar of this slide consisted of hydrogen
sulfide bearing mud, possibly suggesting active fluid seepage and a
vibra-core penetrated ~50 cm of recent sediment overlying colluvium or
landslide debris confirming the age of ~300 years as proposed by Lee
et al. (2004). However, no seeps or indications of recent movement were
observed during our ROV investigation within this narrow head scar
indicating that seafloor in the scar is draped with mud. |
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