Background
The first workshop was held in the Wrigley Marine Science Center of
the University of Southern California at Catalina Island, CA, on August
15-17, 1990. In this workshop state-of-the-art reviews on long-wave
runup were presented. Tsunami run-up and flooding and tsunami run-up
hazard mitigation were the main topics discussed in the workshop. The
workshop brought together researchers from Japan, Russia, England, and
the United States and evidently revitalized research efforts on
long-wave runup, spawning several major research programs on long-wave
runup had commenced in the United States as well as overseas. The
workshop has also facilitated further international research
collaborations. Liu, et al. (1991) reported the proceedings of the
workshop.
From 1992 to 1994 several major tsunamis occurred, including
Nicaraguan tsunami on September 2, 1992; Flores tsunami on December 12,
1992; Hokkaido tsunami on July 12, 1993. All three tsunamis caused
devastating property damages and many deaths. Moreover, in 1994 alone
four additional tsunamis, including the East Java (Indonesia), the
Shikotan Island (Russia/Japan), the Mindoro (Philippines), and the
Skagway (Alaska, USA) tsunamis, occurred around the world. The runup
heights along affected coastlines were surveyed and documented by
various research teams. Different research groups have performed
numerical simulations of all these events with different numerical
models. The community felt the strong need to gather researchers
together to discuss similarities and dissimilarities among these models
and to discuss the difficulties in modeling coastal effects of tsunami.
Consequently, the Second International Workshop on Long-Wave Runup
Models was held at Friday Harbor, San Juan Island, Washington, on
September 12 - 16, 1995. Total of 55 scientists and students
participated in the workshop; it is emphasized that student
participation was encouraged and in fact 21 of the 55 participants were
students. Unlike the first workshop, the format of the second workshop
was designed to focus more on discussions than on formal presentations.
To accomplish this goal, four benchmark problems were selected before
the workshop so that numerical models can be compared, both
qualitatively and quantitatively, evaluated and discussed among the
participants during the workshop. All of the benchmark-problem
descriptions and necessary data were provided to the participants nine
months prior to the workshop. Based on the benchmark problems, each
participant was asked to submit his/her written discussion 50 days
prior to the workshop, and the written discussions were distributed to
each participant 30 days prior to the workshop. The actual laboratory
or physical measurements were only presented during the workshop in the
same format, allowing the comparisons of predictions with measurements.
The four-benchmark problems were the following:
1) The prediction of an edge-wave packet propagation along a uniformly sloping beach,
2) The interaction and runup of incident solitary waves with a conical island,
3) The runup of solitary waves on a vertical wall, and
4) The tsunami runup around Okushiri Island, Japan.
During the workshop, seven discussion themes were organized as
follows: laboratory, analytical, finite-difference, finite-element,
vertical-plane models, boundary-integral-element models, and
marker-and-cell models. All the presentations and discussions were
edited and published in a book entitled "Long-wave runup models" (Yeh,
et al. 1996); some of the general observations are discussed below.
There was no doubt that the benchmark-problem exercises used in the
second workshop proved extremely useful in identifying absolute and
comparative modeling capabilities. Overall, in terms of tsunami runup
modeling, significant advances had been made between two workshops, due
to the advancement of computational capabilities, and because of the
generation of a large 2-D and 3-D laboratory data set and the
fortuitous field measurements in 1992-1995, all of which have
contributed to model calibrations. The tsunami modeling efforts had
become more directed towards their implementation for real tsunami
predictions and hind-castings than ever before. At the time of the
first workshop in 1990, large differences between computed runup
results and field measurements might have been attributed to both
errors in the seismic estimates of the source motion and to the
hydrodynamic calculations, during the second workshop researchers were
much more confident in the hydrodynamic calculations, at least for
non-breaking waves. It was equally clear that reduction and even
elimination of numerical dispersion and numerical dissipation effects
would -if not already- soon become reality. At the same time, the
workshop participants recognized additional and important problems
arising from modeling improvements, such as determination of highly
accurate initial wave conditions, modeling the three-dimensional flow
effects, and turbulence. There is no question that actual tsunami runup
motions are turbulent; the runup flow patterns, impacts, scouring
effects, and sediment transport are all affected by turbulence in the
runup motions.
Since the second workshop in 1995, there have been four additional
large tsunamis resulting in catastrophic loss of life and property.
They are the Peru tsunami in 1996, the Papua New Guinea tsunami in
1998, the Turkey tsunami in 2000 and the Peru tsunami in 2001. Among
these four tsunamis, the Turkey tsunami was definitely caused by land
subsidence and slides associated with earthquakes. On the other hand,
the source of the Papua New Guinea tsunami, which killed more than 2000
people and destroyed completely three villages, remains controversial
and has been postulated as due either to seafloor dislocation or
sediment slump. Because of the occurrence of these two tsunamis,
research interest and efforts on the modeling of landslide generated
tsunamis have been intensified in recent years.
THE THIRD INTERNATIONAL WORKSHOP ON LONG-WAVE RUNUP MODELS
will take place June 11-12, 2004 in Catalina Island, California. The
conference venue is the Wrigley Marine Science Center of the University
of Southern California Center. The National Science Foundation sponsors
the workshop.
References
Liu, P. L.-F., Synolakis, C., and Yeh, H. 1991 "A report on the international workshop on long wave runup", J. Fluid Mech., 229, 678-88.
Yeh, H. Liu, P., and Synolakis, C. (ed.), 1996 Long-wave runup models. World Scientific. |
