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National Science Foundation
Map of Indonesia.

Along with buildings, roads and utility systems, the wave destroyed valuable ecosystems. Afterwards, children stood on bare coral reefs that were once submerged.

Photo of Kerry Sieh.

Kerry Sieh, California Institute of Technology

Credit: © California Institute of Technology

Kerry Sieh, a geologist from Caltech, has studied the off-shore Sumatran earthquake zone for over a decade. In the summer of 2004, in fact, his research team had distributed educational posters and brochures about how to recognize the signs of an impending tsunami.

Sieh and his team flew to Indonesia soon after the Dec. 26, 2004, disaster to survey the damage from Jan. 1 to Jan. 20, 2005. Because of Sieh’s in-country contacts and partners, they  traveled extensively in the area and even met with the vice president of Indonesia, before starting their survey.

The team had several goals. First, they wanted to download information from the Sumatra’s array of global positioning satellite stations. Second, they wanted to explore by air, several islands close to the earthquake’s epicenter to look for evidence of uplift. Third, they hoped to survey the west coast of Aceh, at the northern tip of Sumatra, for evidence of land sink due to the earthquake.

Although they encountered some difficulties, including logistical problems, the theft of equipment at one GPS station and various other delays, they accomplished all three goals.

On Nias Island, off the southern coast of Sumatra, inhabitants reported that the highest wave was about 12 feet. On Simeulue Island (southwest of Aceh), Sieh found that the sea had not returned to its pre-tsunami shoreline. In some cases, over three-feet of water now stands in places that were dry; in others, once-submerged coral reefs are now completely exposed.

Sieh described arriving in Simeulue: “Before we could shut down the engine, 100 or more children and adults swarmed out onto the reef from the trees. We immediately split ourselves into a science team and a relief team. Danny and I began to inspect the corals, while Dayat and Samsir (our pilot and mechanic) began to talk to the villagers and distribute the materials we had brought along as relief aid—clothing, powdered milk, hammers and fishing equipment.”

Read Sieh’s team’s day-by-day account.

Photo of Genus Millepora.

The shifting plates of the magnitude 9.0 earthquake thrust a coral, likely from the genus Millepora, out of the water.

Credit: Kerry Sieh, Tectonic Observatory, California Institute of Technology

Photo of Coral Reefs.

The earthquake pushed this area of the Indonesian shoreline up, exposing fragile coral reefs that were once submerged.

Credit: Kerry Sieh, Tectonic Observatory, California Institute of Technology

A Special Report After the Tsunami