PRESS RELEASE FROM GEORGIA TECH
Community Education and Evacuation Planning Saved Lives in Sept. 29 Samoan Tsunami, Researchers Say
Community-based education and awareness programs minimized the death toll from the recent Samoan tsunami, though there are still ways to improve the warning and evacuation process, according to a team of researchers that traveled to Samoa last month. The team, funded by a National Science Foundation (NSF) grant, collected data Oct. 4 through 11 to document the impacts of the 8.1 earthquake and the ensuing tsunami that occurred on Sept. 29. They examined flow depths, runup heights, inundation distances, sediment depositions and damage patterns at various scales.
“In addition to timing – the fact that the tsunami struck in the daylight morning hours when most people were on their way to work or school – tsunami education, awareness and evacuation exercises really contained the death toll,” noted Hermann Fritz, one of the principal investigators and an associate professor of civil and environmental engineering at the Georgia Institute of Technology. “The technical solution doesn’t always work for coastlines near the epicenter with less than 30 minutes between earthquake and onslaught of the tsunami. Earthquakes with a duration of more than 30 seconds serve as a natural warning, resulting in a spontaneous self-evacuation.”
Nearly 190 people were killed in the tsunami, with the majority of deaths reported in Samoa, a country governing the western part of the Samoan Islands in the South Pacific Ocean. The two main islands of Samoa are Upolu and Savai’i. American Samoa, a territory of the United States southeast of the sovereign state of Samoa, is comprised of main island Tutuila, the Manu’a Islands, Rose Atoll and Swains Island. The Samoan government estimates the total damage from the tsunami at $147 million.
The team’s survey data – especially critical in the immediate aftermath since perishable data would otherwise be lost forever – circled all of the main Samoan islands and spanned 350 kilometers from Ofu in the east to Savai’i in the west. They learned that the tsunami impact peaked at Poloa near Tutuila’s western tip and Lepa at Upola’s southeast coast. Maximum runup heights reached 17 meters at Poloa, and inundation distances and damage were recorded at Pago Pago, more than 500 meters inland. The harbor at Pago Pago, normally well-protected from ordinary storm waves, is a classic tsunami trap vulnerable to long-period tsunami waves.
In addition, researchers noticed a marked difference between the evacuation process in Samoa and American Samoa. While most villagers in Samoa knew to rapidly evacuate after experiencing an earthquake, only a month earlier they had been told that cars help with evacuations, a deadly directive since most roads run parallel to the beach.
“Many perished trapped inside cars waiting in congested small roads or in long lines behind vehicles stopped by landslides or debris on the road,” said Costas Synolakis, principal investigator and professor of civil engineering at University of Southern California. “I have been on more than 20 tsunami field surveys, and in many ways this was one of the most surprising in terms of how carnage varied over fairly short distances. This was also the first time we noted what we suspected: misinformation kills.”
Emile Okal, a seismologist and professor of earth and planetary sciences at Northwestern University, conducted approximately 120 interviews with tsunami survivors in 70 different locations around Tutuila and Upolu. He found that most people were educated about tsunamis and knew how to react because of community-based educational programs, not ancestral stories.
“The last significant tsunami in Samoa occurred in 1917 and was very similar in seismology to the Sept. 29 tsunami. Surprisingly, no one I interviewed said they knew of family members being in a similar situation,” Okal observed. “Since the 2004 Indian Ocean tsunami and the 2007 Solomon Islands tsunami, there has been a concerted effort on the part of the local government in American Samoa to post signs and conduct evacuation drills were conducted in some Samoan communities. Many villages were completely destroyed, so I am impressed that the death toll was not larger. The bottom line is education worked.”
While Synolakis agreed that the death toll was probably minimized due to educational efforts, he said there is still a lot of progress that can be made. While working in the field on Oct. 7, the team experienced a real tsunami warning and witnessed first-hand the tremendous confusion and disorganization that followed.
“Although there are warning signs along the beaches in American Samoa, there is no information about where the evacuation routes are,” he said. “It’s also just as important to let people know when it’s safe to come back as it is to warn them. We definitely have our work cut out for us.”
The collected field data serves as benchmarking and validation of numerical tsunami models with wide-ranging applications including forecasting, warning and sediment transport. The researchers will present their findings at special sessions at the American Geophysical Union Fall Meeting in San Francisco this December. Brief publications summarizing the immediate results will follow in research journals. This survey was partially supported by the Pacific Earthquake Research Center (PEER),
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Interviews conducted by tsunami researcher, Professor Walter Dudley of the University of Hawaii. Posted on the USGS event page:
The link here takes you to pictures taken by NOAA employee Gordon Yamasaki in Pago Pago, Samoa during the tsunami after the magnitude 8 earthquake:
From Lori Dengler, Humboldt State University
The most interesting piece of information I’ve gotten in the past day is an account from a family who were in a boat in Pago Pago harbor during the tsunami – courtesy of HSUalum Orion George. The most jarring part of this account to me is the failure to adequately educate people about what to do when they feel a strong earthquake near the coast. These folks should have immediately evacuated as soon as the shaking diminished enough for them to move. Instead they took the time to go on the internet! They were very fortunate – if the tsunami had been larger, they would not have survived.
“This morning (six hrs ago) we were shaken awake by an earthquake which seemed to have no end! We were aboard Gallivanter and tied side-to a big concrete dock in the heart of Pago Pago, American Samoa. And after living up & down the California coast, I knew this was no minor tremor.
After the rude awakening, Cath & I walked across the dock and chatted with a few of our fellow sailors, one of whom said that he’s just done a Google search on “recent earthquakes” and said that it measured-in at 8.1 and the epicenter was only 120 miles distant.
We returned to Gallivanter and I turned on our laptop and searched the same website. Sure enough there it was… “8.1 earthquake – American Samoa – 20 minutes ago”. I clicked on the “Show Map” option and noticed the epicenter was located south west of Pago Pago… which is located on the southern side of the island.
Just as I was considering the ramifications of that little fact… all hell started breaking loose! Our boat was on the move! My first reaction was to start the engine and dash up on deck to see what was going on. I witnessed the water around us was rapidly dropping! Rapidly! In a blink of an eye, we were on the bottom and the boat was falling away from the dock! Three of our big dock lines popped and we fell right over into the mud – the entire basin we had been floating in only moments ago had completely drained! People were screaming!
Next – the water came flooding back in at an even more alarming rate and the next thing I knew we were floating directly above the dock! Over the concrete slab and drifting toward a young lady we knew (from another boat) who was desperately hugging a power pole and up to her chin in swirling water! I told Cath to cut the two remaining dock lines with our serrated bread knife and to be quick about it!
Right as I put the boat into gear, we were somehow washed back off the dock and into the basin as I advance to full throttle and we accelerated through a floating debris field of floating docks, fuel drums, sinking boats, a shipping container and a barnicle encrusted wreck all of which were spinning in the torrent of rapidly dropping sea level. It was absolute mayhem! As we steered out toward the deep water in the center of the harbor I looked over my shouder and saw what appeared to be a waterfall pouring off the dock and shore beyond. Not one of the dozen vessels remained at the dock. All were underway in a matter of seconds… with or without crews aboard.
We motored around in the middle of the harbor watching the waves of floods & ebbs while wondering about after-shocks and our fellow cruising sailors. As we passed one of our neighbors she shouted to us that her husband had been washed off the dock as they were trying to get away. She was alone and seriously concerned. Other boats broke free from their moorings and anchors in the initial seismic waves and many were driven ashore, or driven under by loose tuna boats.
After about three hours, we felt it was finally safe enough to return to the dock. All we had were lengths of old line and we were short a couple fenders. We were the first to go in and we started un-tangling lines and helping others get back along side the concrete dock. All of the store-fronts along the water are destroyed, roving mobs of kids can be seen looting, the fence around the dock is gone, every boat on stands in a nearby boatyard were washed away. Big fishing boats are now in parking lots across the street. Absolute destruction is seen everywhere along the shore.
Phones and power are down but we got back online right away and I immediately went back to the recent earthquakes website to see if things have been calming down in the center of the earth. A number of aftershocks as strong as 6.0 have been recorded over the past few hours – but thankfully no more wave action has been noticed. We’ve been making Skype calls to our families and letting others use the computer as well to phone home.
Online news reports say that the earthquake lasted three minutes and the highest flood rose 25 ft above normal! There are 20 confirmed deaths… including our neighbor who was swept off the dock. Most fatalities occured in and around the harbor where we live. Boats are battered and nerves are fried. One friend wound-up on his boat nearly 1000 feet away from the water after breaking from his anchor and sailing right down Main St. taking power & telephone wires down with his mast! Some people lost everything… including their lives. We came through remarkably well with only minor dammage sustained to our toe rail when the dock lines parted and to our fender basket which was the only point of contact with that drifting wreck. I never felt any jarring loads while we were hurtling around above & below the concrete dock, so I believe our hull, keel & rudder suffered no dammage from the wildest boat ride I’ve ever been on. “