HF Radar detection of tsunamis Belinda Lipa, James Isaacson, Bruce - PowerPoint PPT Presentation

HF Radar detection of tsunamis Belinda Lipa, James Isaacson, Bruce Nyden, Donald Barrick Codar Ocean Sensors

Analysis for tsunami current velocities, water levels • Two radars measure radial current velocity maps • Radial velocities are combined to give total velocity • Velocities are detrended to estimate the tsunami component • Water level is calculated from detrended velocity & water depth

Hokkaido tsunami Current velocities and water levels

Tsunami detection summary .

Velocity oscillations during the 2011 Japan tsunami

From 2 hrs before the quake until 5 hrs after Around the tsunami arrival

Typical velocity patterns signaling tsunami arrival Hokkaido, Japan Oregon, USA Bodega Bay Pt. Reyes California California

PATTERN RECOGNITION: FOUR STEPS Step 1: Define the “Velocity deviation function” V D (t)

Step 2: Define the “Velocity correlation function” V C (t) 14 12 Velocity (cm/s) 10 8 6 4 2 0.8 0.9 1 1.1 1.2 Time from earthquake (hours)

Example 1: Japan earthquake, March 2011 Kinaoshi, Hokkaido Velocity q-factor (a) (b) 15 12000 10000 10 Bands 1-3 8000 Velocity (cm/s) q factor) 6000 5 4000 2000 0 0 -5 -2000 -2 -1 0 1 2 -2 -1 0 1 2 Time from earthquake (hours) Time from earthquake (hours) (c) (d) 15 12000 Bands 4-6 10000 10 8000 Velocity (cm/s) q factor) 6000 5 4000 2000 0 0 -5 -2000 -2 -1 0 1 2 -2 -1 0 1 2 Time from earthquake (hours) Time from earthquake (hours)

Example 2 Japan earthquake, March 2011 Yaquina Head, Oregon Velocity q-factor (a) 4 (b) x 10 20 5 15 0 Veocity (cm/s) 10 q factor) -5 Bands 2-4 5 -10 0 -15 -5 -10 -20 0 1 2 3 4 0 1 2 3 4 Hours from March 11, 12:00 UTC Hours from March 11, 12:00 UTC (c) 5 (d) x 10 20 0.5 15 0 -0.5 Veocity (cm/s) 10 q factor) -1 5 Bands 4-6 -1.5 0 -2 -5 -2.5 -10 -3 0 1 2 3 4 0 1 2 3 4 Hours from March 11, 12:00 UTC Hours from March 11, 12:00 UTC

Example 3: Indonesia earthquake April 2012 Velocity q-factor Padang, Sumatra Hut Bay, India