Understanding Volcanic Eruptions and Their Impact on Ships

The experience of a volcanic eruption, particularly an eruption that generates a shockwave, can be alarming. Many people wonder what the safest course of action is when such an event occurs. If you are on a ship in close proximity to the volcanic activity, how do you ensure your safety? This article explores the dynamics of shockwaves and provides practical advice for navigating through such scenarios.

Proximity and Safety: Deep Water vs. Shallow Water

The key to safety during a volcanic shockwave is proximity. If you are sailing in deep water and not in the immediate blast zone, the ship is likely to be untouched by the shockwave. The shockwave in the water is typically minimal, only about a few inches above the surface and a considerable distance below it. In deep water, this wave is less noticeable.
However, as the wave enters shallow water, it hits the seafloor, which pushes the wave up. The part of the wave against the seafloor slows down while the crest of the wave moves faster, resulting in a large, breaking wave. This can be extremely dangerous and should be avoided at all costs.

Reacting to the Warning Signs of an Upcoming Tsunami

One of the most critical signs of an approaching tsunami is the sudden retreat of the ocean. A 5th grader saved his family during the 2004 Indonesian Tsunami by recognizing this sign and warning others. However, many people who were unaware of what was happening rushed to the shore to catch fish left on the sand, only to die in the subsequent wave.

During the 2004 Tsunami, my family experienced a similar situation. While camping on the beach in the Florida Everglades, we faced a phenomenon that was effectively a tsunami wave wrapping around the globe. The wave swept well above the high tide level and even entered our tent at night, forcing us to relocate. The news later reported that the high tide was a result of the tsunami wave.

The Experience of a Sailor

My personal experience with a similar situation provides a real-life example. When sailing miles out in the ocean with waves about 4' high, and a floating rope got entangled in the propeller, the decision to dive into the water proved beneficial. The shock of jumping into cold water instantly alleviated seasickness, and the decision to not re-enter the boat was a sound one. This, however, has no direct correlation to dealing with volcanic shockwaves.

Conclusion

In summary, the safety of a ship during a volcanic eruption largely depends on your proximity to the event and the nature of the water. If in deep water and not in the blast area, remaining on the ship is generally the safest course of action. If in shallow water or on the shore, recognizing the signs of an imminent wave and seeking higher ground or deep water is critical. Always keep safety as your top priority during such incidents.