Did you feel it?

Some did, others didn’t. On Thursday, 200 miles west of Coos Bay, the Earth’s crust shifted again. This shift was substantial; a magnitude 6.3. This quake was not “the big one” but it was big enough that people in Portland felt it. Fortunately, this quake did not generate a tsunami.

What if this quake was “the big one” or did produce a tsunami? Tsunamis move at about 400 miles per hour. A tsunami generated 200 miles off our coast would have arrived in Coos Bay about a half hour after the quake; not much time to get out of the way.

What if an LNG plant was operating in Coos Bay during an event that produces a tsunami? An LNG ship taking on cargo at the Jordan Cove terminal would have had half an hour to detach from the dock and get out of the bay. Jordan Cove has told us it will take 90 minutes for an LNG ship to move from the dock to the open ocean. Even in ideal conditions, a half hour of transit would only get an LNG ship part way out of the bay, that is if the tide is deep enough for a ship to even leave the berth.

Loaded LNG ships have drafts deeper than the Coos Bay Federal navigation channel. This means LNG carriers can’t transit the bay at low tide. They need tides higher than six feet to safely transit the channel. Thursday’s earthquake happened at 8:02 am. If this quake had generated a tsunami, the first wave would have arrived at the harbor entrance around 8:30. At 8:30 a.m., the tide was too low for an LNG ship to leave the berth. The high tide that day was 6.1 feet around noon so there would not have been enough water in the channel to move an LNG ship much before 11 a.m.

This example demonstrates that a LNG ship, parked at the proposed Jordan Cove terminal, would have been trapped at the berth. It could not have departed because the navigation channel was too shallow at 8.30 a.m. to allow the ship to maneuver without running aground. Big ships don’t do well near shore during tsunami events. Yes, tsunamis are infrequent, but they are high consequence events. Having an LNG tanker rattling around the bay during a tsunami will only make a bad situation worse.

Michael Graybill

Coos Bay

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