My mother called from Melbourne Australia on New Years Eve.   I always have mixed feelings when she calls; happy that she has but a bit guilty because I know that I should have called myself.   She is 86, retired long ago and living on far less than I do.   I should call.  


I offered to call right back but she insisted that she had a cheap calling plan and that it wasn't costing much, so we talked about family and then, inevitably the Indian Ocean tragedy.   I am a geophysicist and have talked to the media quite a bit since the event.   “Could it happen here?” is the most common question.   Reasonable I suppose, but I find I don't even want to answer it, partly because it is difficult to give an answer in a clear understandable way, but also because somehow it seems very self-directed given the scale of the tragedy that has taken so many lives in places far away.   This isn't about us.  


My mother wanted to tell me how annoyed she was at the stories told in interviews with Australian tourists who survived the tsunami and were returning back home, telling of their harrowing experiences but never once mentioning those who died.   Australia is home turf to the Murdoch Press and it doesn't get much worse, so maybe the tourists did have words of sympathy for the victims and they never got aired.   My mother knows this of course but still she said, “They should just shut up; shut up, go home and be thankful they are alive”.   I had been having similar thoughts.   I have lived in the US for nearly 27 years and see my mother rarely, but it seems I am still her son.  


I imagine if I had been on vacation in Phuket with my family and survived the ordeal, returned to New York and had been asked by a reporter to recount the incident I too would have offered some thoughts about our narrow escape.   But mostly I would have wanted to just shut up and go home.   I would want just to retreat into the safety of a place that is not likely to be touched by such tragedy.   “Those poor people” she said, meaning the thousands and thousands who have died, lost family, been displaced and are now hungry and sick with their future livelihoods threatened.  


Poor, is what they are (were) and why they suffered so much.  


On December 26 th the Earth handed out about as much punishment as it is capable of handing out.   Earthquakes greater than magnitude 9.0 do happen but at that level it starts not to matter too much any more.   It's even hard for scientists to calculate the magnitude accurately when earthquakes get so large.   This 9.0 earthquake cracked a huge length of the crust, from the epicenter just off Sumatra north through the Nicobar and Andaman Islands , more than 1000 km.; the distance from Boston to Washington .   Even the aftershocks, always smaller than the main shock, have themselves been large, rivaling the size of the Northridge quake causing justifiable concerns for additional tsunamis.    The crust beneath the ocean where the earthquake occurred may have moved by 30 meters or more vertically.   That's what caused the tsunami. The entire column of water above the shifting crust responds either by doming up or making a massive trough.   Either way it creates a huge wave that travels far faster than the common wind-driven waves on the surface of the ocean that we see at the beach.   Technically, tsunami and common ocean waves are completely different, but that too doesn't matter very much.   It is a massive wave-like onslaught from the ocean against which humans are largely defenseless, especially those who are poor.


It is a sad but understandable fact that the poorest always suffer the most at the hands of Nature .   Repeatedly we hear in the news media of the thousands who die in storms in poor countries like Bangladesh while meteorologically similar storms take few lives in our country.   This year four hurricanes raged through the Gulf Coast and Florida taking more than 100 lives.   The very same storms came through Haiti taking thousands.   For the year, including storms in May, Haiti has probably lost close to 6000. The1989 earthquake in Loma Prieta, California (magnitude 6.9) left 63 dead and about 3,700 injured while the similar 2001 Bhuj quake in Gujarat, India, (magnitude 7.6) killed over 13,000 and injured more than 100,000.   The differences are well known and well documented and can be thought of in the harsh language of mortality risk.   An American, for example, is about 45 times more at risk of experiencing a flood than a Somalian, yet the Somalian is 85 times more at risk of dying in a flood than someone in the U.S.   For every type of natural event, whether earthquake, landslide, storm, flood, drought or volcano the poorest are at the greatest risk.   Drought causes mortality risk only for the poorest – no one dies from a drought in a rich country anymore.   The last time that happened in the US was du ring the du st bowl of the 1930s  


It's understandable for many reasons.   The poor live in the most fragile dwellings.   The graphic video we have seen on television or the Web was taken by tourists a couple of floors up in hotels near the beachfront that obviously survived, while thousands of indivi du al family dwellings were swept away.   Whole villages are now known to have disappeared.   It would be a serious mistake to think that the tsunami was more intense in the places where the damage was the greatest.   The damage is greatest where the structures are weakest and almost inevitably they are the homes of the poorest.   Had these dwellings been built like the hotels more people would have survived.   Not everyone of course.   A tsunami like that of December 26 th will take lives no matter how strongly we build.   But stronger structures have a better chance of survival than weak ones, so the rich who live in them have a better chance of survival than the poor.   It's that simple.  


So while the proximate cause of death may be drowning, the real killer is poverty.   Poverty kills the poor in many ways.   They are susceptible to infectious diseases like malaria, a disease that only kills the poor.   They die of wholly preventable or treatable illness like diarrhea, usually from drinking fetid water, a cause of death unknown in the rich world.   Underweight associated with chronic malnutrition, particularly in children is a leading factor in morbidity and mortality in poor countries – only in poor countries. And like all the ills of the poor world women and children suffered the most.   Pregnancy alone puts women at 250 times greater risk of death than in the US , Japan or Europe .   Make a map of the world color-coded by infant mortality rate or malnutrition and you've made a poverty map. The extreme poor lack all normal attributes of a decent, dignified life: adequate food, housing, sanitation, health care, e du cation, employment and freedom. Everything they lack makes them more susceptible to Nature's excesses.


It was overwhelmingly these people who faced the tsunami on the 26 th and became its victims.   When the tsunami came poor women and children, lacking the strength to swim, climb to high ground or cling to something floating to hold them above water again died in disproportionate numbers,  


In other settings the risks the poor face are different. Urban poor who have often migrated from even more impoverished rural regions have little choice but to live in high risk, “informal settlements” around major cities; in river banks subject to flooding or the scars of landslides on denuded slopes as they do around Caracus and may other cities.   They chose these places, not out of preference but because they are available, the rich knowing better than to live there, and because they must get close enough to places where they can obtain work within walking distance.  


And all too often attempts by the poorest to improve their situation backfire The poor who died in Haiti this last year in a sense, brought it on themselves. Haiti, the poorest country in the western hemisphere has been almost completely deforested in part to create land for low-yielding crops but also by the very poorest people, who burn trees for charcoal to be sold for a pittance to obtain enough food to live.   Deforestation was the principal cause of the flood disaster because the foliage normally holds the runoff and prevents flash floods and mud slides.   Unwittingly, a perilous feedback loop is formed in which attempts to cope with poverty themselves amplify the conditions that pro du ce further poverty and put the poor at greater risk.


The cities into which to poorest now crowd are most often port cities where goods are pro du ced with their cheap labor and can be exported without expensive inland transport.   The urban slums that are home to these people are the most squalid places on Earth.   And they are the most vulnerable to any of Nature's excesses.  


So, the answer to the question “Can it happen here” that I recoil from is “no”.   We are rich.   There are no slum dwellers.   Our buildings are for the most part strong.   Our drinking water supply is a safe distance away. Our emergency management is capable.    Our hospitals are excellent.   Our communications systems are wonderful.    It can't happen here.   Not like it did in the Indian Ocean .  


But that's not what the question asks when asked by the media.   It is whether a geophysically similar event could take place and to that the answer is different    Tsunami can be generated by earthquakes like the one on the 26 th .   They don't need to be so large but smaller earthquakes will cause smaller tsunamis.   The east coast of the US does not face a region where major earthquakes are generated that could cause tsunami.   But tsunamis can and have be caused by other mechanism.   The most common is a large undersea landslide that we call a slump.   The basic idea is simple enough; start something like an underwater landslide (a snow avalanche is the same sort of thing) and the water above will be displaced in a manner something like the way an earthquake moves crust around.   That will generate a wave.   Like earthquakes, the bigger the slump the bigger the wave.   It's a bit like jumping into a swimming pool, the bigger bathers make the bigger splashes.  


Across the Atlantic Ocean , more or less opposite New York (a bit to the south) are the Canary Islands .   Islands like the Canaries are the emergent tips of large volcanoes that rest on the sea floor several thousand meters below.   Islands like these, especially if they are volcanically active are known to pro du ce slumps, some very large (we know that from sonar images of the sea bottom around the islands).   Major slums from the Hawaiian Islands are very well documented in sonar images.   No one argues about whether these have occurred.


To make a significant tsunami hit the US east coast would require that a very large chunk of rock come off the side of one of the Canary Islands, probably the result of a volcanic eruption (the Mt St Helens eruption pro du ced a huge landslide).   It would have to remain pretty much in one piece (if it broke into fragments, and they mostly do, it would spread out thinly over the ocean bottom and make smaller waves) and slide quickly down slope.   It could happen.   Sonar images around the Big Island of Hawaii reveal some very large blocks at the foot of the island.   The worst affected areas from a Canary Island slide would be nearby in coastal Morocco , but a large wave could travel across the Atlantic and arrive in New York after about 8 hours.   In the worst case scenario the wave could be well above 30 feet high (some calculations suggest a much bigger wave is possible).   That would do a lot of damage.   I live in Piermont, a small village on the Hudson and my wood frame home is well less than 30 feet above the water level.   I would know where to go to get away from the water and it fortunately isn't very far.   I know that the schools that my children attend are on fairly high ground, as is the place my wife works.   They'd be fine.   But when the water receded we might go home to find, well, no home.   A 30 foot wave would engulf many low lying areas of lower Manhattan , flow up 125 th street , and submerge large areas of Brooklyn .   All the airports would go under water.   At Kennedy planes would be washed into Jamaica Bay .   Much of Coney Island would probably not survive.   Many lives would be lost.  


The follow up to the “could it happen here” question is always, “what are the odds that it will happen?”   It's almost impossible to answer in a useful way.   Mayor Bloomberg, apparently a closet geophysicist, has said the chances are small.   So we partied on for New Year's Eve.   The ball dropped just the same over Times Square as if nothing had happened.   And for us, nothing did happen.  


What if I said the odds are one in 10,000?   What would follow from having such a number?   What good is knowing such a number?   The sedimentary deposits from such waves are pretty easy to see in the geological record and, as far as I know, the record does not contain evidence of prior large tsunami events.   So perhaps I should say that having never happened before that we know of a tsunami will never happen again.   That's a very risky proposition.   The very largest geological events are thankfully very rare but their consequences are devastating.   They are low probability/high impact events and they are the hardest of all to understand and anticipate.   To make a very large tsunami that would be truly destructive to New York would require a worst case scenario slump in the Canaries.   But a worst case scenario earthquake happened off Sumatra on December 26 th .and more than 140,000 people have died as a consequence.   The worst cases do happen.   It's just very difficult to say when the next worst case event will occur even though we can be quite certain that it will.  


It makes sense to be prepared.   We don't have to panic the population but civil defense people, police, firefighters, National Guard etc should know what to do; how to mobilize people to get to higher ground or up into strong buildings.   We should have a map of where the hospitals that are the highest locations.   Stewart Airport would need to understand how to move into center stage.   And yes, there should be a warning system in the Atlantic Ocean just like the one in the Pacific to detect the approach and tell us how big the wave will be.   The technology is all known and it works.   We should monitor the Canary Islands better.   Fortunately volcanic eruptions of the type that might trigger a slump generally let you know they are coming through tremors, ground motion and small eruptions.   Volcanoes don't surprise us very often any more, although it's hard to know just how large the eruptions are going to be.   A warning system is a sort of insurance.   Monitoring and warning systems don't cost much relative to the potential losses.   We have fire insurance on our houses, not because we know they will burn down, and we hope they won't, but because we know they could.    We don't know that the Three Mile Island Nuclear Plant will blow up but we have evacuation plans (kind of), not because we know it will, but because we can envisage the terrible consequences of an explosion, and certainly not because we have the odds calculated.   We don't know that there will be a tsunami ……



That's the “could it happen here” answer.   I could make a more technical answer and many of my colleagues will be doing that and debating what to do exactly.   But it's still the question I don't really want to answer right now because right now it's not about us, and what might happen to us, it's about so many poor people so far away to whom it did happen.   If the worst case comes to pass in the Atlantic like it did in the Indian Ocean , a warning system would literally save us a lot of grief.   Grief, like love is perhaps one of a very few truly universal emotions, shared by all people everywhere.   Only the most devout seem to be able to hold in their hearts love for all the world's people.   Perhaps it's beyond human capacity to grieve for someone you never knew.   If it is, then perhaps we should all just shut up and go home.