Should you take your kids to the beach to watch the tsunami? After December's heart-wrenching loss of life in the Indian Ocean, it might seem safe to assume everyone knows to head for the hills. But this lesson has yet to take root, judging by the response of some to last week's valuable dry run for our own tsunami disaster.
Not often does Earth's cracked shell of massive sliding, diving and mountain-building plates provide such a perfect teaching aid as it did last week when a significant undersea earthquake sparked a West Coast tsunami warning. We got to see how prepared, and unprepared, we are for a subduction zone disaster here.
Based on recurring events over the course of thousands of years, scientists promise a catastrophic break in our nearby ocean-bottom Cascadia Subduction Zone. Geological pressure is building there as one of the planet's crustal plates bulges upward as another plunges beneath it.
When the tension between two plates becomes too intense, a vast store of energy is suddenly released in the form of an earthquake of magnitude 9.0 and greater. With a final death toll of 176,000 and another 50,000 still missing, the great quake in the Indian Ocean off the island of Sumatra is a stark example of what can happen here.
The big question is when. The average interval between great plate-boundary quakes here is 500 to 600 years. The longest is about 1,000 years. This is somewhat comforting, since our last subduction quake was in January 1700, when scientists say a 32-foot wave hit the Oregon and Washington coasts. Unfortunately, that sense of comfort is spoiled by the fact that some of the past earthquakes had intervals less than the time that has elapsed since the 1700 earthquake.
There is no indication Tuesday's tumbler in northern California waters was a precursor to something more serious. But the response to it reveals a need for better public and private preparation for the real monster-in-waiting.
Believe it or not, there were families with children on the beach at a time when it was still unclear whether the danger had passed. If there is one key thing to remember about tsunamis, it is to get away from the beach and stay away until you are certain an official all-clear message has been issued.
In the most dangerous circumstance - a large quake in the subduction zone near our own shoreline - there will likely be no chance for an official warning. Strong shaking may continue for three minutes of more. As soon as the shaking stops, get as far away from and as high above the ocean as possible, and stay there. Many lives can be saved by following this advice.
Other vital lessons from last week include the need to periodically test communications systems. Among other flaws, the emergency alert system failed to trip alarms at local radio stations. The success of other public notification systems was hit-and-miss, at best. Some key officials weren't notified, while others were uncertain what to do - whether to sound warning sirens, call other agencies, or order evacuations.
There were also discrepancies in when city leaders sounded their sirens. It is commonsense to have a very short delay after a city receives an alert to make sure police officers and firefighters are in position; but Seaside's 52-minute delay was simply appalling.
Just as officials need to formulate and practice better tsunami procedures, each family needs to assemble an emergency kit of food, water, blankets, medications and other essentials. Discuss with loved ones how each will respond if disaster strikes while children are at school or spouses are at work. Agree on a phone contact number outside the coastal area where messages can be exchanged - after an earthquake it often is easier to get through to a long-distance number than to a local one.
We have a precious opportunity to learn and incorporate the lessons from last week's incident in our emergency response planning. We may not get another warning.