Preliminary Simulations of the Algerian Tsunami of 21 May, 2003 in the Balearic Islands

Jose C. Borrero

University of Southern California

Tsunami Research group

EARTHQUAKE DETAILS

Magnitude 6.8

Date 2003 05 21

Time 18:44:19 UTC

Location 36.90N 3.71E

Depth 10.0 kilometers

Reports of waves in the Balearic Islands

email - alerted to waves at "about 10:30 to 10:45 local time (2030 - 2045 UTC), continuing on until after midnight with a period of approximately 10-15 minutes, and a peak amplitude at our dock in excess of 2 meters, approaching 3 meters"

news 1 : "las oscilaciones en las aguas litorales de Menorca se iniciaron a las 21.00 horas y prosiguieron hasta las 23.30 horas, cada vez con menos intensidad." started at 9:00 local (1900 UTC) "movimientos de las olas, que en algunos casos alcanzaron 150 centímetros de oscilación" - 150 cm oscillations

news2: "olas de dos metros, con una frecuencia estimada de al menos 12 minutos" 2 m waves, 12 min period but no arrival time information

Tsunami simulations were performed with MOST (Method of Splitting Tsunami), a 2+1 dimensional computational model of the non-linear shallow water wave equations. The Simulations were performed on two different sized grids for the two conjugate fault plane solutions.

Bathymetry, Gridding and Fault Parameters

 Bathymetry: 2 minute bathymetry from Smith and Sandwell: (http://topex.ucsd.edu/marine_topo/mar_topo.html)

the small grid was interpolated directly from the big grid. 4x resampling over a specified region.

GRIDDING

 BIG GRID

NX = 601, dx = 2.847 km

NY = 393. dy = 2.824 km

 SMALL GRID

NX = 780, dx = 709 m

NY = 640, dy = 702 m

FAULT PARAMETERS

Algeria 1

L = 36.5 km, W = 18.3 km

dislocation = 1.0 m

strike, slip, dip = 56, 46, 71 deg.

Algeria 2

L = 36.5 km, W = 18.3 km

dislocation = 1.0 m

strike, slip, dip = 237, 43, 92 deg.

SIMULATION RESULTS

 BIG GRID, Algeria 1

 SMALL GRID, Algeria 1

 BIG GRID, Algeria 2

 SMALL GRID, Algeria 2

Summary

A tsunami was generated after the earthquake of May 21, 2003 along the coast of northern Algeria. The media has reported significant, damaging waves in the ports along the southern coasts of the Balearic Islands north of the epicentral region. Early reports describe waves of 1 to 3 m in amplitude which damaged many hundreds of vessels in the various harbors.

Waves from the earthquake region are computed to arrive at the ports in the islands approximately 40 to 60 minutes after generation.

Very early eyewitness and news reports give conflicting arrival time information.

We are awaiting information on exact arrival times and on better bathymetry to update simulation results.

Animations - REQUIRE QUICKTIME PLAYER OR PLUGIN

 Big Grid, Source 2

Small Grid, Source 1

Small Grid, Source 2