Expert: Dr Thomas Bell - 11/4/2009

Question
Hi Mr. Bell,

Thank you for offering to answer our questions here. :-)
I live in puerto Vallarta mexico and was wondering if I am likely to feel the Big One (earthquake) that is supposed to happen anytime in California. If I can feel it from here then will it just be something small like 3 or below? I am considering moving to Mazatlan and worry because it is closer. I am a born and raised California girl (Los Angeles) and way to chicken to ever live back home. I do worry about my family back home. Have you heard or know of what the survival rate would be for that? Sorry for the crazy questions. I am so scared for my family and wonder what chances that have to survive.

Answer
Katelin,

Pardon my math.  The odds of dying in an earthquake between 1980 and 2001 are closer to 1 in 528,000.  (Estimated population in 1990 divided by average earthquake deaths per year)

It is estimated that between 1980 and 2001 approximately 200,000 people died and 500,000 people were injured in earthquakes around the world.  The odds of dying in an earthquake in any given year were about 1 in 528,000.  The estimated deaths in the United States from earthquakes and their aftermath since 1800 is about 4,000 of which 3,000 are estimated to have died in the San Francisco earthquake in 1906.  It is unlikely that the number of fatalities in the next big earthquake in California will be anywhere near this.  The modern buildings, emergency services, and health care facilities in early 21st century America are a far cry from the ramshackle wooden city that burned to the ground in 1906.  The number of people who die each year in earthquakes world wide is a minute fraction of those who die from auto accidents, smoking, food poisoning, crime, drinking, drowning, or a host of other risks you probably don't worry about much.

I suppose the bad news from your perspective is that most of the west coast of North and South America has an elevated risk of seismic activity.  That would of course include Mexico and California. Movement on some of the numerous faults from Tierra del Fuego to Nome has been monitored for many decades now and the probability of future movement can be estimated particularly in places that are more intensely studied like California.  Just because we know there will be an earthquake is not much help predicting when it will happen or even how large an individual event will be.

Unlike Mexico, California enforces strict building codes to reduce damage and injury in the event of an earthquake.  The ability of the state and federal government to respond to natural disasters is significantly greater and more sophisticated than most other parts of the world.  Your family is probably safer in LA than you are in either Mazatlan or Puerto Vallarta.

Here are a few websites on this subject you might find interesting including this earthquake last week near Vera Cruz Mexico:

http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/us2009niat.php
http://aje.oxfordjournals.org/cgi/content/full/161/12/1151
http://earthquake.usgs.gov/earthquakes/