Guam and Seattle

HOW IS GUAM LIKE SEATTLE?

by Homer Montgomery

0159 Z - R/V Melville, steaming west, just south of Tinian

As we steam back and forth mapping the ocean floor, I have been thinking about the curious parallel between Seattle and Guam. What in the heck am I talking about? Are there any parallels at all between Seattle and Guam? Let’s see, cool and wet versus hot and sticky? Starbucks headquarters versus the world’s largest K-Mart? Flowered cotton shirts year-round versus natural wool sweaters? Give up?

It turns out that there is a parallel, and everyone now knows its name. Earthquake. The recent earthquake in Seattle was a deep focus temblor produced in a subduction zone. The Big One (as it is known on Guam) occurred on August 8, 1993. Actually, the Big One was two earthquakes with different foci occurring seven seconds apart. The epicenters were deep. Magnitude was 8.1 or 8.2. Shaking definitely was intense. Liquefaction did occur. No one died. Damage was not catastrophic.

Both cities learned lessons. Deep focus quakes tend to be less dangerous. Aftershocks are not too bad. No matter, residents of Seattle and of Guam have renewed respect for the word vulnerable. They also know a thing or two about subduction zones and trenches.

I would like to make an observation about the stark differences in the way the earthquakes were received on opposite margins of the Pacific. The U.S. news media called Guam inquiring about loss of life. None? Ok, how about catastrophic damage? None? Click. The breathless reporting of massive damage in Seattle was, as usual, way overdone. The Japanese showed great interest in the Guam quake. They wanted to know why such a large quake did not kill anyone. They were looking for lessons that they could apply to their own earthquake-prone country. Japan sought to save lives. The U.S. desperately wanted to report deaths. Guam simply got on with its business. Different perspectives of similar phenomena.

Vocabulary: Magnitude, Focus (foci), Epicenter, Liquifaction, Subduction zone, Trench

The following map is from the U.S. Geological Survey.

Shown are earthquakes of the Mariana Trench region (including Guam and Saipan to the north).

The earthquakes are concentrated within the subduction zone.

Communications | Humankind | Ecology | Geology