Coastal Solutions

Saturday, October 31

tchase — Fri, 06 Nov 2009 12:56:19 +0000

On our last day, we toured the eastern and southern Upolu coasts, where the tsunami had its biggest impact. We were struck by the widespread devastation, not dissimilar from that of hurricanes (cyclones). In a few low-lying locations there was evidence that the tsunami reached inland approximately 1 kilometer.

Unlike in American Samoa (Tutuila), there were long, straight stretches of sandy beaches. In many of these beach communities, the tsunami caused total damage to both beach fales and the residential homes located on the landward side of the coastal road.

Rubble-mound revetments lined much of the coastal area. Due to the relatively small stone size, these revetments were heavily damaged by the tsunami in most areas. For example, in Satitoa, on the eastern coast, stones were strewn across the coast, with many stones transported tens of meters inland.

Toward the end of the day, we stopped in Poutasi, a small coastal village situated just to the east of a National Park. Unlike some of the totally devastated coastal communities to the east, damage to residences and public buildings in Poutasi varied from total destruction to partial destruction. This was likely due to a relatively lower flood depth in this region. Of note was a newly constructed home on the beach which appeared to be structurally sound, although damage to windows and interior walls was evident. The village church also sustained some damage; indicated by destruction of lower window-panes only, the water level reached about midway up the wall.

At the end of the day we returned to Apia via the cross-island road, stopping at our host’s plantation to pick fresh bananas for the following day’s breakfast.

– ASCE/COPRI tsunami assessment team

Lesley Ewing, P.E., Team Leader, Coastal Engineer, California Coastal Commission

Jennifer L. Irish, Ph.D., P.E.; Assistant Professor, Texas A&M University

Friday, October 30

tchase — Fri, 06 Nov 2009 12:53:45 +0000

On arrival in Western Samoa we were struck by both the marked landscape and cultural differences between Western and American Samoa. An independent country with a population of 170,000, Western Samoa has a more urban and touristic feel than its American counterpart. The mountains of Upolu, the most populated of the Western Samoan islands, are less constraining than those in American Samoa (Tutuila). This afforded the opportunity for communities to relocate and spread into higher ground in response to the devastating cyclones of 1990 and 1991. Thus, residential villages along the Upolu coast were, in general, more dispersed, and many had residences spread through upland as well as coastal areas.

During this first day in Western Samoa, we met with another ASCE member, Bill Gordon, and his business partner Tom Tinai of Tinai, Gordon, and Associates LTD, based in the urban center Apia. Bill and Tom shared their local knowledge on coastal, transportation and residential construction and then we talked about structural performance during the tsunami.

Of particular note, they told us about Bailey bridge, built originally for a stream crossing on the north coast and recently relocated to Salani. While sustaining some abutment toe-protection damage, the bridge maintained its structural and functional integrity during the tsunami, even though the tsunami waves reached the bridge deck— which we later confirmed during our site visit.

– ASCE/COPRI tsunami assessment team

Lesley Ewing, P.E., Team Leader, Coastal Engineer, California Coastal Commission

Jennifer L. Irish, Ph.D., P.E.; Assistant Professor, Texas A&M University

Thursday, October 29

tchase — Thu, 05 Nov 2009 10:55:04 +0000

We spent most of the day in meetings with the American Samoa Government (ASG) and the various federal agencies. We first met with the ASG Department of Public Works director and staff to discuss building code issues. Then we met with a local architect and an engineer from (Western) Samoa who happened to be in Pago Pago that day—he would later accompany us on our visit to Samoa. Finally, we met with National Oceanic and Atmospheric Administration (NOAA) and Department of Homeland Security (DHS) staff who work on land planning issues.

We returned to the field late Thursday afternoon, visiting the village of Masefau on the north side of the island. Tsunami elevations were lower here and damage was less severe than most of the other villages we visited. However, some older, wood-frame buildings close to the bay shoreline were destroyed or heavily damaged.

Although the shoreline was lined with a stone revetment extending several feet above grade, the tsunami overtopped the structure and flowed into the village. The two-story school building, which was constructed of concrete and reinforced masonry, was already back in use; first floor windows had been replaced, rooms had been cleaned and repainted, etc.

We also met the owner of a new house that had been elevated approximately three feet above grade on concrete and reinforced masonry foundation walls. The tsunami had entered the house, with flood depths of a few inches, but the house sustained far less damage than other, lower houses nearby.

At the end of the day, we returned to our hotel, Tisa’s. Chris then headed to the airport, where he boarded the first of several planes that would take him home to North Carolina. Lesley and Jennifer remained, preparing to travel to Samoa the next day.

– ASCE/COPRI tsunami assessment team

Lesley Ewing, P.E., Team Leader, Coastal Engineer, California Coastal Commission

Jennifer L. Irish, Ph.D., P.E.; Assistant Professor, Texas A&M University

Christopher P. Jones, P.E.; Senior Engineer, Christopher P. Jones & Associates

Wednesday, October 28

tchase — Wed, 04 Nov 2009 10:47:25 +0000

Wednesday began with a trip to the east end of the island. We planned a stop at Auasi, where there is a terminal for a small ferry between the main island of Tutuila and the island of Aunu’u, and Tula, a village near the eastern tip of the main island.

The stone breakwaters protecting the ferry harbor appeared to be in good condition with no apparent damage. Tsunami inundation and runup at the site appeared to be modest, reaching no more than a few feet above the protective structures and the ground elevation. However, there was some flood damage to houses built at or near grade landward of the harbor site.

Tula, which is located at the eastern end of the island, was damaged extensively. The community had no revetment or seawall, but the post-tsunami beach was still about 45-feet-wide and there was a beach berm measuring up to about 13 to 14 feet MSL. Also, we found that a lot of coral pieces had been washed inland, through peoples’ homes and across the road.

The visit to Tula revealed higher inundation levels and much more damage to buildings. Many homes were destroyed or heavily damaged, and residents were living in tents provided by the Red Cross or staying with relatives in homes on the hillsides. The elementary school and 15 to 20 homes or fales were seaward of the main road. All the homes seaward of the road were damaged extensively and many were completed destroyed from waves washing through the homes. Most of the homes along the coast are one-story, have concrete slab on grade foundations and are constructed with reinforced masonry walls (some have concrete columns with masonry infill walls), wood roof systems and metal roofing. The tsunami water level appeared to have come close to the eaves of many of the homes. The homes north of the school were on slightly higher ground than those to the south, and the damages seemed related to elevation, with some buffering by the beach and berm. We were told that many people were afraid to sleep in their tents or damaged houses at night for fear of another tsunami.

The school had extensive inundation damage, though it was being cleaned and painted while we were there—it was scheduled to reopen on November 2. The concrete and reinforced masonry school was better built than most of the houses in the area. This was a common observation by the team: government buildings, schools and churches, while damaged, tended to survive the tsunami, while many adjacent homes were destroyed.

While in Tula, we met a village “Matia” (chief) who worked as a counselor at the school. His house was next to the school and was completely destroyed. Fortunately, he and his family escaped before the waves struck. He helped to evacuate the school children up a nearby road on the hillside. A school administrator said the children had been taught to go up that hill after an earthquake, in the event that a tsunami was triggered by the quake. We found it very encouraging to learn that many people knew to evacuate once the earthquake stopped, even without an official warning. Because they evacuated, all the school children were unharmed.

We agreed that the damage to the Tula was major, though not as catastrophic as the damage to Paloa, which we visited on Tuesday afternoon. However, it was among the harder hit areas we saw.

Following the visit to Tula, we went to the very top of the evacuation hill where a National Oceanic and Atmospheric Administration (NOAA) observatory is perched high above the village, affording us a good view. The observatory is one of the stations used by NOAA to monitor baseline solar radiation and atmospheric gasses—part of its climate change monitoring program. That location was selected for the observatory because the area is believed to have the cleanest air on the planet, and universities and laboratories around the world use samples from this observatory for their research. It was almost surreal to think of the contrast between the island’s recent devastation and its place on the front lines of possible future global change.

The team then traveled to Pago Pago and met the local University of Hawaii Sea Grant agent. Right now, American Samoa is a microcosm of all the marine research groups, and, post-tsunami, it seems that everyone who can help is doing so. The Sea Grant agent had a mini-van and offered to take us to Fagasa on the north side of the Island. Fagasa Bay was also hard hit by the tsunami, even though the earthquake that generated the waves occurred south of American Samoa.

Again, we visited a school and spoke with an administrator, and again, we were told that all the children had been evacuated safely up a steep hillside road near the school. Many homes in the village were destroyed or heavily damaged. The older, one-story school buildings close to the shoreline were damaged (some heavily) and undergoing repairs, but the newer two-story classroom building was already back in use when we visited (the first floor had sustained some flood damage, but it had already been cleaned up and repaired).

At the end of the day, we returned to Pago Pago, where we viewed damage along the northwest side of the harbor, one of the hardest hit areas. The tsunami wave elevation increased here due to the narrowing and shoaling at the head of the harbor. The velocity of the wave here was also very high—this video was shot from Pago Plaza. The video shows that the initial wave traveled across the parking lot in about ten seconds, quickly reaching several feet in depth and propelling cars into nearby buildings.

– ASCE/COPRI tsunami assessment team

Lesley Ewing, P.E., Team Leader, Coastal Engineer, California Coastal Commission

Jennifer L. Irish, Ph.D., P.E.; Assistant Professor, Texas A&M University

Christopher P. Jones, P.E.; Senior Engineer, Christopher P. Jones & Associates