Evidence of Quake Damage Minimal at Start
The third of as many as seven ASCE reconnaissance teams is in Japan studying the impact on infrastructure caused by the 9.0 magnitude earthquake and tsunami on March 11. Following teams sponsored by the Structural Engineering Institute and the Geo-Institute, the third team is sponsored by the Coasts, Oceans, Ports, and Rivers Institute, and as such will be focused on damage to port structures. It is being led by Marc Percher, P.E., M.ASCE, a senior engineer with Halcrow Group in Oakland, Calif. He is a structural analyst and designer specializing in marine oil terminals and refinery structures. Percher and/or his teammates will be discussing their findings and experiences in regular posts.
Read each day's entries:
Introduction | Day 1 | Day 2 | Day 3 | Day 4 | Day 5 | Day 6
Day 1 -- Wednesday, May 11
By Bill Bruin, P.E., M.ASCE
Today, Marc is letting me write a few words to update our team’s daily diary. Actually, he is too busy right now to write, coordinating our first day’s field activities with our Japanese guides. As I write, the team is fully assembled and in transit on the Shinkansen (Japan Rail Bullet Train), traveling at approximately 200 kilometers per hour to Sendai, our first destination.
Today’s activities involved getting acclimated to the time zone, to Japan, and to our upcoming mission. After waking up at 3 a.m. (thanks to jet lag) and then answering emails till 6 a.m., we were fully prepped for the day’s agenda. We had already put out the morning fires, tackled some of our real-world responsibilities, and were dressed as what would be good impersonators of Japanese salarymen (suits and ties, although I was a rebel wearing my brown suit, instead of the traditional navy or black).
With a few hours to kill before our first meeting, we were ready for a quick exploration of Tokyo (although some persuasion was necessary to convince the team leader that we would not get lost and be back in time for our first meeting). Going through Tokyo, there were no obvious signs that the country had been hit by the biggest earthquake they've ever recorded. Except for a few out-of-service escalators or some darkened hallways dimmed to conserve energy, I would never have known a major earthquake had struck only two months ago.
However, we did manage to justify our sightseeing, as on the Imperial Palace grounds, we stumbled upon our first signs of earthquake-related damage -- spalled plaster off a masonry wall of one of the Palace buildings. Of course we documented our findings, and present them here for future research purposes.
By 10 a.m., we were back at the hotel and ready for business. We then met with Daniel Cox from Oregon State University, who is on a one-year sabbatical at Kyoto University. He just completed a field reconnaissance of tsunami-impacted sites north of Sendai with the (SEI-sponsored) ASCE 7 tsunami loading team. He was able to give us a great briefing on what to expect over the next few days as well as a few pointers for success. Since the COPRI coastal team and our COPRI team are there concurrently, this was also a chance for us to get to know our sister team members before we both hit the road. Dan was very generous in sharing his data and insight with us, and we are sure it'll come in handy in the coming days. After the briefing, we knew we were in for a sobering and fascinating view of Mother Nature’s power.
After Dan's briefing, we were invited to attend a conference conducted by PARI (Japanese Ports and Airports Research Institute) discussing their findings to date with respect to the earthquake and tsunami. This was a big event attend by nearly 400 participants and the local media, and we even managed to get a shout-out as special guests (not that we understood it that well, being that the presenters were all speaking Japanese). With some translation support, we listened to various presenters discussing topics such as the historical seismicity of Japan, the March 11 event itself, the observed earthquake and tsunami impacts, and the Japanese early warning systems for both earthquakes and tsunamis. In addition, they handed us a large packet of information (in Japanese) that I am sure will be of use to the team, just as soon as we can have Yoshi read it all.
A few interesting items that we learned about included tsunami run-up values as high as 30 meters (check them out at coastal.jp/tsunami2011), that there was little damage associated with shaking north of Sendai as the damage observed was dominated by the tsunami, and that the Sendai region has settled by as much as a meter and moved laterally by approximately 5 meters. Once again, PARI is proving their excellent skills and incredible hospitality in this reconnaissance.
Supplement by Marc Percher
At 3:30 a.m., I felt my first aftershock -- a half-second of strong motion in my body’s “wrong!” direction, followed by a second or two of free body movement that wakes you up, saying “how YOU doin.’”
As I looked around the hotel room afterward, I was struck by what I didn’t see. In my hotel room in Talcahuano, Chile, the wallpaper had rips and the TV had obviously been thrown from its stand, small damages all around that reminded one that they’re in a seismic region. Here there is no such evidence. Up on the fourth floor of our Tagajo, Japan, hotel, the walls are pristine and the TV is strapped down (much as I hope yours is at home). This exemplifies the great success story the Tohoku earthquake would have been -- had there been no tsunami.
In the northern region we are touring, there is an ironic lack of evidence of shaking-only damage, though admittedly there must be some that had been washed away by the tsunami. Away from the inundation areas, we’ve seen little damage, and what damage there is has been minor. Of course, the bad news is that the tsunami did occur, and our hotel’s front lobby was flooded up to 1.5 meters. The amazing thing is they’ve already replaced all the drywall, tiling, etc.
While as a seismic designer all I want to see is strong motion damage, which I can predict and validate in my mathematical models, the real story here is the tsunami damage, which is drastic, hard to predict, and not very satisfying when the solution is “run like hell!” This week we’ll be controlling our urge to focus merely on problems we can solve with concrete detailing and instead consider the larger issues of the interface of shaking, evacuation, inundation, impact, repair, and recovery. But if we get the occasional morning vibratory alarm clock, it’ll at least make us feel like there’s some major successes we can note.
Introduction | Day 1 | Day 2 | Day 3 | Day 4 | Day 5 | Day 6