Earthquake hazards map study finds deadly flaws, researcher suggests improvements

Aug 31, 2012

(Phys.org)—Three of the largest and deadliest earthquakes in recent history occurred where earthquake hazard maps didn't predict massive quakes. A University of Missouri scientist and his colleagues recently studied the reasons for the maps' failure to forecast these quakes. They also explored ways to improve the maps. Developing better hazard maps and alerting people to their limitations could potentially save lives and money in areas such as the New Madrid, Missouri fault zone.

"Forecasting earthquakes involves many uncertainties, so we should inform the public of these uncertainties," said Mian Liu, of MU's department of . "The public is accustomed to the uncertainties of forecasting, but foreseeing where and when earthquakes may strike is far more difficult. Too much reliance on earthquake hazard maps can have serious consequences. Two suggestions may improve this situation. First, we recommend a better communication of the uncertainties, which would allow citizens to make more informed decisions about how to best use their resources. Second, seismic hazard maps must be empirically tested to find out how reliable they are and thus improve them."

Liu and his colleagues suggest testing maps against what is called a null hypothesis, the possibility that the of an earthquake in a given area – like Japan – is uniform. Testing would show which mapping approaches were better at forecasting earthquakes and subsequently improve the maps.

Liu and his colleagues at Northwestern University and the University of Tokyo detailed how hazard maps had failed in three major quakes that struck within a decade of each other. The researchers interpreted the shortcomings of hazard maps as the result of bad assumptions, bad data, bad physics and bad luck.

This video is not supported by your browser at this time.
Watch a five 5-minute video summary presented at the 2012 UNAVCO science workshop “Bad assumptions or bad luck: Tohoku’s embarrassing lessons for earthquake hazard mapping”

Wenchuan, China – In 2008, a struck China's Sichuan Province and cost more than 69,000 lives. Locals blamed the government and contractors for not making buildings in the area earthquake-proof, according to Liu, who says that hazard maps bear some of the blame as well since the maps, based on bad assumptions, had designated the zone as an area of relatively low earthquake hazard.

Léogâne, Haiti – The 2010 earthquake that devastated Port-au-Prince and killed an estimated 316,000 people occurred along a fault that had not caused a major quake in hundreds of years. Using only the short history of earthquakes since seismometers were invented approximately one hundred years ago yielded hazard maps that were didn't indicate the danger there.

Tōhoku, Japan – Scientists previously thought the faults off the northeast coast of Japan weren't capable of causing massive quakes and thus giant tsunamis like the one that destroyed the Fukushima nuclear reactor. This bad understanding of particular faults' capabilities led to a lack of adequate preparation. The area had been prepared for smaller quakes and the resulting tsunamis, but the Tōhoku quake overwhelmed the defenses.

"If we limit our attention to the earthquake records in the past, we will be unprepared for the future," Liu said. "Hazard maps tend to underestimate the likelihood of quakes in areas where they haven't occurred previously. In most places, including the central and eastern U.S., seismologists don't have a long enough record of earthquake history to make predictions based on historical patterns. Although bad luck can mean that quakes occur in places with a genuinely low probability, what we see are too many 'black swans,' or too many exceptions to the presumed patterns."

"We're playing a complicated game against nature," said the study's first author, Seth Stein of Northwestern University. "It's a very high stakes game. We don't really understand all the rules very well. As a result, our ability to assess earthquake hazards often isn't very good, and the policies that we make to mitigate earthquake hazards sometimes aren't well thought out. For example, the billions of dollars the Japanese spent on tsunami defenses were largely wasted.

"We need to very carefully try to formulate the best strategies we can, given the limits of our knowledge," Stein said. "Understanding the uncertainties in hazard maps, testing them, and improving them is important if we want to do better than we've done so far."

Explore further: Computer simulations suggest aridification of Sahara occurred longer ago than thought

More information: The study, "Why earthquake hazard maps often fail and what to do about it," was published by the journal Tectonophysics.

Related Stories

New hazard estimates could downplay quake dangers

Apr 16, 2008

The dangers posed by a major earthquake in the New Madrid and Charleston, South Carolina zones in the Midwestern and Southern parts of the United States may be noticeably lower than current estimates if seismologists adjust ...

Geological evidence for past earthquakes in Tokyo region

Jan 31, 2012

In 1923, a magnitude 7.9 earthquake devastated the Tokyo area, resulting in more than 100,000 deaths. About 200 years earlier, in 1703, a magnitude 8.2 earthquake struck the same region, causing more than 10,000 deaths.

Japan's seismologists blinded to March 11 quake: journal

Apr 13, 2011

Japan's seismologists were so entrenched in outdated beliefs about seismic hazard that they became blinkered to the risk of the March 11 mega-quake, a commentary in a top science journal charged on Wednesday.

Earthquakes actually aftershocks of 19th century quakes

Nov 04, 2009

(PhysOrg.com) -- When small earthquakes shake the central U.S., citizens often fear the rumbles are signs a big earthquake is coming. Fortunately, new research instead shows that most of these earthquakes ...

Recommended for you

First eyewitness accounts of mystery volcanic eruption

20 minutes ago

New light has been shed on one of the biggest volcanic eruptions in the last 500 years—the so-called 'Unknown eruption'—thanks to an unusual collaboration between a historian and a team of earth scientists at the University ...

Scientists monitoring Hawaii lava undertake risks

7 hours ago

New photos from the U.S. Geological Survey's Hawaiian Volcano Observatory give a glimpse into the hazardous work scientists undertake to monitor lava that's threatening to cross a major highway.

NASA sees Odile soaking Mexico and southwestern US

18 hours ago

Tropical Storm Odile continues to spread moisture and generate strong thunderstorms with heavy rainfall over northern Mexico's mainland and the Baja California as well as the southwestern U.S. NASA's Tropical ...

NASA sees Tropical Storm Polo intensifying

19 hours ago

Tropical storm warnings now issued for a portion of the Southwestern coast of Mexico as Polo continues to strengthen. Infrared imagery from NASA's Aqua satellite showed powerful thunderstorms around the center ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

cantdrive85
1 / 5 (3) Aug 31, 2012
Any improvement will need to acknowledge the Sun-Earth electric circuit inter-connectivity. There is an extremely strong correlation to solar activity and earthquakes here on Earth.

Google; "Sunspots and Earthquakes"

Here is a peer reviewed article on the matter.

"Rocks That Crackle and Sparkle and Glow: Strange Pre-Earthquake Phenomena",
by Dr. Friedemann T. Freund, a professor in the Department of Physics, San Jose State University, and a senior researcher at NASA Ames Research Center.
julianpenrod
1 / 5 (7) Aug 31, 2012
Just so much doggerel to skirt around the truth.
To begin with, this change in policy wouldn't be being suggested now if it was necessary in the past! If earthwuakes occurred where they weren't expected, there would have a massive change in the procedure more than ha;lf a century ago! Of course, the New World Order expects their target audience to ignore this eminent proof because they live by, "Everybody in the past was stupid, everybody today is a genius!"
In fact, the earthquakes, like the derechos forming where they weren't known, the tornadoes occurring where they were never seen, the crack in the ground in Michigan, the fault suddenly reported running the length of the Eastern Seaboard are all expressions of God's anger at the country. You'll see standard after standard toppled, the old ones declared "inefficient from the start", just to avoid mentioning that things are happening now that wouldn't otherwise!