Table Of ContentPREDICTING THE UNPREDICTABLE
PREDICTING THE UNPREDICTABLE
The Tumultuous Science of
Earthquake Prediction
Susan Elizabeth Hough
with a new preface by the author
Princeton University Press Princeton & Oxford
Copyright © 2010 by Princeton University Press
Published by Princeton University Press, 41 William Street, Princeton, New
Jersey 08540
In the United Kingdom: Princeton University Press, 6 Oxford Street,
Woodstock, Oxfordshire OX20 1TR
All Rights Reserved
Third printing, first paperback printing, with a new preface by the author,
2016
Paperback ISBN: 978-0-691-17330-6
The Library of Congress has cataloged the cloth edition as follows:
Hough, Susan Elizabeth, 1961–
Predicting the unpredictable : the tumultuous science of earthquake
prediction / Susan Hough.
p. cm.
Includes bibliographical references and index.
ISBN 978-0-691-13816-9 (hardcover : alk. paper) 1. Earthquake prediction.
I. Title.
QE538.8.H68 2010
551.22 —dc22 2009008380
British Library Cataloging-in-Publication Data is available
This book has been composed in Bembo and Berthold Akzidenz Grotesk
Printed on acid-free paper. ∞
press.princeton.edu
Printed in the United States of America
10 9 8 7 6 5 4 3
Contents
Preface to the Paperback Edition / vii
1. Ready to Rumble / 1
2. Ready to Explode / 12
3. Irregular Clocks / 29
4. The Hayward Fault / 39
5. Predicting the Unpredictable / 47
6. The Road to Haicheng / 58
7. Percolation / 86
8. The Heyday / 96
9. The Hangover / 108
10. Highly Charged Debates / 125
11. Reading the Tea Leaves / 141
12. Accelerating Moment Release / 150
13. On the Fringe / 158
14. Complicity / 171
15. Measles / 191
16. We All Have Our Faults / 196
17. The Bad One / 206
18. Whither Earthquake Prediction? / 222
Acknowledgments / 231
Notes / 233
General Index / 255
Index of Earthquakes by Year / 261
Preface to the Paperback Edition
At the beginning of 2010, just as the first edition of this book was
published, an ominous red square appeared on the earthquake.
usgs.gov website. The square fell within the island nation of Haiti, per-
ilously close to the capital city of Port-au-Prince. Red meant an earth-
quake within the past hour. The size of the square meant magnitude 7.
At that time, I had never worked in Haiti, never visited Haiti, and
never expected to work in Haiti. And yet I knew immediately, with
wrenching certainty, this can’t be good. Indeed, the world watched
with horror as the images began to emerge: catastrophic damage to
buildings and human bodies alike.
Too many bodies, in fact, to count. The estimated death toll went
on to become an issue in its own right, with official estimates climbing
in the early weeks from 150,000 to 200,000, and then to over 250,000.
Later estimates based on more rigorous statistical approaches quietly
lowered this estimate to closer to 100,000. The scope and scale of the
disaster, however, remained staggering by any measure. While news
media often flock to the sites of especially severe damage after earth-
quakes, conveying an inflated impression of the overall damage, the
city of Port-au-Prince had truly been left shattered. A later, very thor-
ough study revealed that two out of ten structures in Port-au-Prince
had sustained severe damaged or total collapse, and another three out
of ten had been damaged enough to be unsafe. The grim reality
greeted me personally when I landed in Port-au-Prince about eight
weeks later to lead a team that worked with Haitian partners to install
portable seismometers to record aftershocks. Over the years that fol-
lowed I met and worked with some of the finest people I have ever
had the privilege to know, and I came to appreciate the strength and
vibrancy of Haiti and her people. The ordeal that they endured, and
continued to recover from years later, was, for most people, beyond
imagination.
viii Preface to the Paperback Edition
Seven short weeks after the 2010 earthquake, the much larger mag-
nitude 8.8 Maule earthquake rocked much of Chile. The much lower
death toll (525) from the much larger earthquake added an exclama-
tion point to the saying that my late colleague and friend Nicolas Am-
braseys coined decades ago: earthquakes don’t kill people, buildings
kill people. Unlike Haiti, Chile has had a long standing awareness of
earthquake hazard and, maybe more notably, the political will and eco-
nomic means to mitigate risk.
But where Maule was largely a success story, a different kind of
story played out less than a year later when the even more massive,
magnitude 9 Tohoku earthquake rocked northern Japan. If Haiti was
among the least prepared countries in the country in the world, Japan
arguably was, and remains, the best prepared. Yet the Tohoku earth-
quake unzipped a part of the plate boundary that most if not all ex-
perts had thought capable of producing earthquakes “only” as large as
low magnitude 8s. In fact, Japan’s well-built structures and infrastruc-
ture rode out the shaking from the monster magnitude 9 earthquake
quite well, with few instances of serious damage or collapse from the
shaking. If the story had ended there, it would have been chalked up as
another success story; another illustration of the value of preparedness
and the success of modern building codes.
The story did not, as we all know, end there. The larger-than-ex-
pected earthquake unleashed a larger-than-expected tsunami that ca-
reened into the coast line, a freight train the size of an ocean. It quickly
overwhelmed sea walls and entire villages. In the best prepared coun-
try on earth, over 15,000 people lost their lives, and the nuclear power
plant at Fukushima experienced a catastrophe that will reverberate for
decades to come.
Haiti, Maule, Tohoku. Three different earthquakes, three different
outcomes, but one thing in common: none of these earthquakes had
been predicted. All three occurred in regions long known, at least
among Earth scientists, to be active earthquake zones. Scientific pa-
pers had been published underscoring the long-term hazard in all
three zones. Yet, while earthquake predictions continue to be made
Preface to the Paperback Edition ix
regularly by earthquake professionals and amateur predictors alike,
nobody sounded immediate alarm bells before any of these three
major events.
Researching this book gave me the opportunity to talk to col-
leagues who, unlike me, had been active in the field during the earth-
quake prediction “heyday” of the 1970s. I asked several of them, why
had optimism given way so quickly to pessimism about the viability of
earthquake prediction? One answer I heard was that for all of the op-
timism about prediction methods during the 1970s, predicted earth-
quakes failed to materialize, while sometimes catastrophic events con-
tinued to strike with no prior warning.
As they say, the more things change, the more things stay the same.
This book describes several methods that researchers now think might
someday lead to viable short-term prediction. Older and wiser, no-
body claims that reliable earthquake prediction is right around the
corner. Many, if not most, experts doubt that reliable short-term pre-
diction will ever be possible. Still there are perhaps faint, cautious
glimmers of something akin to hope. One of the most notable devel-
opments in earthquake science in recent decades has been the new
recognition of so-called slow-slip events that occur along subduction
zones, typically along plate boundaries but at deeper depths than
where the plate boundary is locked and loaded. A slow-slip event hap-
pens when a deep patch of the plate boundary moves slowly, over a
period of days or weeks, without generating any seismic waves. The
question arises immediately: Could such an event be the straw that
breaks the camel’s back, triggering subsequent large earthquakes on
adjacent locked patches of the fault? Slow-slip events remain one of
the hottest topics in the field, with some indication that such events
have indeed preceding several notable large earthquakes. And so we
are where we’ve been many times in the past: aware of fatal flaws with
what appeared earlier to be promising methods, but wondering if a
new approach might pan out. And maybe it will, some day. As Charles
Richter said in the 1970s, nothing is less predictable than the develop-
ment of an active scientific field.
