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 California California

• Pt. Reyes

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

0.8 0.9 1 1.1 1.2 2 4 6 8 10 12 14 Velocity (cm/s) Time from earthquake (hours)

Step 2: Define the “Velocity correlation function” VC(t)

• 2
• 1

1 2

• 5

5 10 15 (a) Velocity (cm/s) Time from earthquake (hours)

• 2
• 1

1 2

• 2000

2000 4000 6000 8000 10000 12000 (b) q factor) Time from earthquake (hours)

• 2
• 1

1 2

• 5

5 10 15 (c) Velocity (cm/s) Time from earthquake (hours)

• 2
• 1

1 2

• 2000

2000 4000 6000 8000 10000 12000 (d) q factor) Time from earthquake (hours)

Example 1: Japan earthquake, March 2011 Kinaoshi, Hokkaido Velocity q-factor Bands 1-3 Bands 4-6

Example 2 Japan earthquake, March 2011 Yaquina Head, Oregon Velocity q-factor

1 2 3 4

• 10
• 5

5 10 15 20 (a) Veocity (cm/s) Hours from March 11, 12:00 UTC 1 2 3 4

• 10
• 5

5 10 15 20 (c) Veocity (cm/s) Hours from March 11, 12:00 UTC 1 2 3 4

• 20
• 15
• 10
• 5

5 x 10

4

(b) q factor) Hours from March 11, 12:00 UTC 1 2 3 4

• 3
• 2.5
• 2
• 1.5
• 1
• 0.5

0.5 x 10

5

(d) q factor) Hours from March 11, 12:00 UTC

Bands 4-6 Bands 2-4

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