Sandra B. Rogers, Director · Office of Communications/108 Reno, NV 89557-0053 · 775-784-4941 · FAX: 775-784-1422 · www.unr.edu News Release For immediate release Date: April 7, 2000 Editor's Note: call John Anderson at (775) 784-4265; Gene Ichinose at (775) 784-4260. An animated model of the tsunami/seiche effects is at http://quake.seismo.unr.edu/htdocs/WGB/LakeTahoeTsunami/

By Pat McDonnell

(775) 784-1583 <pqm@scs.unr.edu>

RENO -- Waves as high as 30 feet could damage some Lake Tahoe shoreline communities if another magnitude 7.0 earthquake on the Richter scale buckled faults under the lake in a manner similar to the prehistoric past, University of Nevada, Reno seismologists say.

By analyzing an adjacent fault five miles from the lake, doctoral student Gene Ichinose and Seismological Laboratory director John Anderson can explain how a severe fault upheaval like ones that have occurred at the lake about every 1,500 years would create an initial wave, called a tsunami, followed by seiche waves that may roll back and forth against the shore. While the danger appears slimmer than for a catastrophic forest fire, were a big quake to hit today, shoreline houses, businesses and roadways would be in great peril.

``When nearby residents ask, `What is the probability of a 7.0-magnitude earthquake happening under Lake Tahoe?' we don't really know,'' Ichinose said. ``We can't go to the bottom of the lake and sample the faults. But by looking at the adjacent Genoa fault, I'd say one reasonable estimate would be a 3 to 4 percent chance of that happening in the next 50 years. This is a much lower probability than the occurrence of a devastating forest fire or flood. Nevertheless, shoreline residents should be aware of the danger and move to high ground in the event of a large earthquake.''

Ichinose and Anderson, who helped research the 4.9 magnitude Incline Village earthquake on Oct. 30, 1998, are presenting new research on the lake's seismic hazards in an article submitted for the April 15 edition of the Geophysical Research Letters journal. Nevada geological sciences faculty Richard Schweickert and Mary Lahren, as well as Kenji Satake, one of the world's leading experts on tsunamis and an earthquake researcher for the Geological Survey of Japan, are co-authors of the paper.

Ichinose will present the team's assessment of the potential hazard to Tahoe's lakeside communities at a Seismological Society of America meeting, April 10-12 in San Diego.

The 30-foot waves would crash the shore in a few places where wave energy is focused, according to the researchers' model. Almost the entire shoreline could experience 10-foot waves.