Tides and Tsunamis

Causes of Tides Interaction of earth and moon Interaction of earth and moon Two bulges on either side of the planet Two bulges on either side of the planet Moon’s gravity pulls and moves the water Moon’s gravity pulls and moves the water Opposite side due to centrifugal force of earth and moon’s rotation Opposite side due to centrifugal force of earth and moon’s rotation Rise and fall as Earth rotates Rise and fall as Earth rotates

Spring and Neap Tides Sun also exerts gravitational force on Earth’s water Sun also exerts gravitational force on Earth’s water Spring Tide - Higher tides when sun and moon are aligned Spring Tide - Higher tides when sun and moon are aligned Neap Tide - Lower tides when sun and moon are at 90 degrees to one another Neap Tide - Lower tides when sun and moon are at 90 degrees to one another

Types of Tides diurnal tide – a regular pattern of one high tide and one low tide each day (uncommon) semidiurnal tide – a cyclic high water/ low water sequence that is repeated twice in one day

Importance of Tides Influence near shore life Influence near shore life Circulate water in bays and estuaries Circulate water in bays and estuaries Trigger spawning Trigger spawning Kona Tides Kona Tides Kona Tides Kona Tides

What does a tide chart tell you?

Tide Chart Practice 1. Are Hawaii tides mostly diurnal or semi- diurnal? 2. What day has the lowest tide? 3. What is the highest tide for this month? 4. What time does the sun rise tomorrow? Sets? 5. When we went night tidepooling on the 10 th was the tide rising or going down?

Tsunamis Causes Causes earthquakes under the ocean's floor which vertically shifts the overlying water (around plate boundaries) earthquakes under the ocean's floor which vertically shifts the overlying water (around plate boundaries) landslides which displace large amounts of ocean water landslides which displace large amounts of ocean water Any large disturbance to sea floor or water column Any large disturbance to sea floor or water column

Tsunami Early Warning Center Locations: Oahu and Alaska Locations: Oahu and Alaska monitors the Pacific basin to evaluate potential earthquakes monitors the Pacific basin to evaluate potential earthquakes an area must be located more than 464 miles from the source to have enough time to evacuate an area must be located more than 464 miles from the source to have enough time to evacuate

Hawaii Tsunamis 221 people have been killed 221 people have been killed 1946 (Alaska) and 1960 (Chile) – Hilo, Big Island Hawaii 1946 (Alaska) and 1960 (Chile) – Hilo, Big Island Hawaii

Laupahoehoe

Ring of Fire