Image: Earthquake map
USGS
A map from the U.S. Geological Survey shows the distribution of earthquakes around the world as of Monday. The colors show how recently the quake took place (blue indicates within the past 24 hours, yellow indicates within the past week). The size of each box reflects seismic magnitude.
By
updated 3/28/2011 12:43:26 PM ET 2011-03-28T16:43:26

Here's some good news in the wake of Japan's disaster: A new study says big earthquakes don't set off other dangerous ones around the globe.

Big quakes do trigger local aftershocks, but researchers found no sign of setting off moderate-sized events beyond about 600 miles away.

That won't surprise most experts, said lead study author Tom Parsons. But it's different from his prior research, which did find a global effect for setting off small quakes, said Parsons, of the U.S. Geological Survey in Menlo Park, Calif.

  1. Science news from NBCNews.com
    1. NOAA
      Cosmic rays may spark Earth's lightning

      All lightning on Earth may have its roots in space, new research suggests.

    2. How our brains can track a 100 mph pitch
    3. Moth found to have ultrasonic hearing
    4. Quantum network could secure Internet

Parsons and Aaron Velasco of the University of Texas at El Paso reported the work online Sunday in the journal Nature Geoscience.

They looked at worldwide earthquake records for the 30 years ending in 2009. There were 205 big earthquakes, with magnitude of 7 or more, and 25,222 moderate ones with magnitudes between 5 and 7.

Then the researchers looked at the timing of these events for evidence that the larger quakes triggered the moderate ones. They checked for delays of up to 24 hours, long enough to let the seismic waves from the big quakes peter out.

They did find an increase in moderate quakes, but only within about 600 miles of the initial event, and nearly all within 375 miles. At distances beyond 600 miles, the number of moderate quakes after a big event was no higher than normal.

While the study didn't look at whether big quakes trigger other big quakes far away, the new data suggest they do not, Parsons said. Anyway, since the world averages only about seven quakes at magnitude 7 or above per year, any such effect would have been noticed already, he said.

The new result agrees with what most seismologists believe just from experience, said Klaus Jacob of Columbia University's Lamont-Doherty Earth Observatory. "It's nice to see it confirmed with a thorough study," Jacob said.

Parsons said that after the magnitude-9.0 Japan event on March 11 he watched the global map of earthquakes to look for any distant effect. He saw none.

"It appears to fall in line with what we've seen before," Parsons said.

© 2013 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

Video: Journalist warns disaster in Calif. may be next

  1. Closed captioning of: Journalist warns disaster in Calif. may be next

    >> in the wake of japan's devastating earthquake there is new speculation that the san andreas fault in california will be the source of the next big tremor. simon winchester writes about the strong possibility in this week's "newsweek" magazine. good morning.

    >> good morning.

    >> the magazine references the scariest earthquake to come in california . last time it ruptured was in 1906 when the earthquake and subsequent fires devastated san francisco . what makes you think the timing is right for it to happen again?

    >> it's ee's clear that the earthquakes tend to occur in clusters. a cluster seems to have happened in the last year around the pacific plates. if you think of it as a square, we have had a major earthquake in the northwestern side of the square, tokyo, three days ago it was sendai. on the 22nd of february we had christchurch in new zealand in the southwest of the square. last year we had a major earthquake in chile and the southeast of the square. the fourth leg of the square, the fourth side is where the san andreas and the kcascadia forms. that hasn't ruptured. so now is the time when people should start thinking about what might happen if, one, the san an andreas or the cascadia fault ruptures. if either ruptures there could be major problems.

    >> do you see it as a possibility or do you believe it is inevitable.

    >> it is inevitable. the question that troubles everyone is precise bli whly when. the u.s. geological survey says we can't predict it with accuracy but says the hayward fault is ripe for a rupture within the next quarter century. the san andreas fault , no one is sure. the cascadia subduction zone would cause not just terrifying problems on land but would generate a tsunami. that's a big problem.

    >> if the san andreas fault were to rupture that would not trigger a tsunami?

    >> not essentially. most of the san andreas runs on land and it's mostly under land. if that were to rupture it would cause freeways and bridges to collapse as the disaster did in 1989 . but cascadia is under ground. the problem there is tsunamis. california , washington and oregon haven't experienced tsunamis since 1964 .

    >> how do we prepare for it if we can't predict when it will happen?

    >> that's the problem for a tsunami. of course there are evacuation routes all over california . but are people psychologically prepared for a disruption on the san andreas fault ? generally not. they're better than they were five years ago when we had the anniversary of the san francisco earthquake which was in 2006 . people suddenly got back into the thought that, my god, this could happen. schools started doing exercises and people started retro-fitting buildings and so on and so forth. it's taken 22 years, for instance, since the quake in 1989 and still the bay bridge , one of the major arteries from the east bay across to san francisco is still not finished. california really isn't taking this seriously enough. maybe the events in japan, chile and new zealand will remind them that they could be -- and i don't want to be alarmist -- but they could be next. they must prepare.

    >> dire warnings from simon winchester this morning. thank you very much.

    >> thanks, meredith.

Map: Japan earthquake

Photos: After Japan's earthquake and tsunami - week 8

loading photos...
  1. A radiation measuring instrument is seen next to some residents in Kawauchimura, a village within the 12- to 18-mile zone around the Fukushima Daiichi nuclear plant, on April 28. Most residents of Kawauchimura have evacuated in order to avoid the radiation, but some remain in the area of their own accord. (Koichi Kamoshida / EPA) Back to slideshow navigation
  2. A brazier heats the house of Masahiro Kazami, located within a 12-mile radius of the Fukushima Daiichi nuclear plant, April 28. (Koichi Kamoshida / EPA) Back to slideshow navigation
  3. Volunteers help clean a cemetery at Jionin temple in Ishinomaki, Miyagi prefecture, northeastern Japan, on April 29. Many volunteers poured into the disaster-hit region at the beginning of the annual Golden Week holiday. (Hiro Komae / AP) Back to slideshow navigation
  4. Japanese government adviser Toshiso Kosako is overcome with emotion during a news conference on April 29 in Tokyo announcing his resignation. The expert on radiation exposure said he could not stay on the job and allow the government to set what he called improper radiation limits for elementary schools in areas near the tsunami-damaged Fukushima nuclear plant. (AP) Back to slideshow navigation
  5. Fuel rods are seen inside the spent fuel pool of the Fukushima Daiichi nuclear plant reactor 4 on April 30. (Reuters) Back to slideshow navigation
  6. A volunteer girl from Tokyo works to clean the debris of a house in Higashimatsushima, northern Japan, on April 30. (AP) Back to slideshow navigation
  7. Farmer Tsugio Sato tends to his Japanese pear trees in Fukushima city, May 1. He said he expects to harvest the pears in October. Farmers and businesses face so-called "fuhyo higai," or damages stemming from the battered reputation of the Fukushima brand. (Hiro Komae / AP) Back to slideshow navigation
  8. Members of Japan Ground Self-Defense Force in protective gear receive radiation screening in Minamisoma in Fukushima prefecture, after searching for bodies at an area devastated by the March 11 earthquake and tsunami. (Reuters) Back to slideshow navigation
  9. Ruriko Sakuma, daughter of dairy farmer Shinji Sakuma, rubs a cow at their farm in the village of Katsurao in Fukushima prefecture on May 3. Thousands of farm animals died of hunger in the weeks following the quake. (Yoshikazu Tsuno / AFP - Getty Images) Back to slideshow navigation
  1. Editor's note:
    This image contains graphic content that some viewers may find disturbing.

    Click to view the image, or use the buttons above to navigate away.

  2. Editor's note:
    This image contains graphic content that some viewers may find disturbing.

    Click to view the image, or use the buttons above to navigate away.

  3. Editor's note:
    This image contains graphic content that some viewers may find disturbing.

    Click to view the image, or use the buttons above to navigate away.

  4. Editor's note:
    This image contains graphic content that some viewers may find disturbing.

    Click to view the image, or use the buttons above to navigate away.

Explainer: The 10 deadliest earthquakes in recorded history

  • A look at the worst earthquakes in recorded history, in loss of human life. (The March 11, 2011, earthquake and tsumani that affected eastern Japan is not included because the fatalities caused, about 15,000, are fewer than those resulting from the temblors listed below.) Sources: United States Geological Survey, Encyclopedia Britannica

  • 1: Shensi, China, Jan. 23, 1556

    Magnitude about 8, about 830,000 deaths.

    This earthquake occurred in the Shaanxi province (formerly Shensi), China, about 50 miles east-northeast of Xi'an, the capital of Shaanxi. More than 830,000 people are estimated to have been killed. Damage extended as far away as about 270 miles northeast of the epicenter, with reports as far as Liuyang in Hunan, more than 500 miles away. Geological effects reported with this earthquake included ground fissures, uplift, subsidence, liquefaction and landslides. Most towns in the damage area reported city walls collapsed, most to all houses collapsed and many of the towns reported ground fissures with water gushing out.

  • 2: Tangshan, China, July 27, 1976

    Chinese Earthquake
    Keystone  /  Getty Images
    1976: Workers start rebuilding work following earthquake damage in the Chinese city of Tangshan, 100 miles east of Pekin, with a wrecked train carriage behind them. (Photo by Keystone/Getty Images)
    Magnitude 7.5. Official casualty figure is 255,000 deaths. Estimated death toll as high as 655,000.

    Damage extended as far as Beijing. This is probably the greatest death toll from an earthquake in the last four centuries, and the second greatest in recorded history.

  • 3: Aleppo, Syria, Aug. 9, 1138

    Magnitude not known, about 230,000 deaths.

    Contemporary accounts said the walls of Syria’s second-largest city crumbled and rocks cascaded into the streets. Aleppo’s citadel collapsed, killing hundreds of residents. Although Aleppo was the largest community affected by the earthquake, it likely did not suffer the worst of the damage. European Crusaders had constructed a citadel at nearby Harim, which was leveled by the quake. A Muslim fort at Al-Atarib was destroyed as well, and several smaller towns and manned forts were reduced to rubble. The quake was said to have been felt as far away as Damascus, about 220 miles to the south. The Aleppo earthquake was the first of several occurring between 1138 and 1139 that devastated areas in northern Syria and western Turkey.

  • 4: Sumatra, Indonesia, Dec. 26, 2004

    Aerial images show the extent of the devastation in Meulaboh
    Getty Images  /  Getty Images
    MEULABOH, INDONESIA - DECEMBER 29: In this handout photo taken from a print via the Indonesian Air Force, the scene of devastation in Meulaboh, the town closest to the Sunday's earthquake epicentre, is pictured from the air on December 29, 2004, Meulaboh, Aceh Province, Sumatra, Indonesia. The western coastal town in Aceh Province, only 60 kilometres north-east of the epicentre, has been the hardest hit by sunday's underwater earthquake in the Indian Ocean. Officials expected to find at least 10,000 killed which would amount to a quarter of Meulaboh's population. Three-quarters of Sumatra's western coast was destroyed and some towns were totally wiped out after the tsunamis that followed the earthquake. (Photo by Indonesian Air Force via Getty Images)

    Magnitude 9.1, 227,898 deaths.

    This was the third largest earthquake in the world since 1900 and the largest since the 1964 Prince William Sound, Alaska temblor. In total, 227,898 people were killed or were missing and presumed dead and about 1.7 million people were displaced by the earthquake and subsequent tsunami in 14 countries in South Asia and East Africa. (In January 2005, the death toll was 286,000. In April 2005, Indonesia reduced its estimate for the number missing by over 50,000.)

  • 5: Haiti, Jan 12, 2010

    Haitians walk through collapsed building
    Jean-philippe Ksiazek  /  AFP/Getty Images
    Haitians walk through collapsed buildings near the iron market in Port-au-Prince on January 31, 2010. Quake-hit Haiti will need at least a decade of painstaking reconstruction, aid chiefs and donor nations warned, as homeless, scarred survivors struggled today to rebuild their lives. AFP PHOTO / JEAN-PHILIPPE KSIAZEK (Photo credit should read JEAN-PHILIPPE KSIAZEK/AFP/Getty Images)

    Magnitude 7.0. According to official estimates, 222,570 people killed.

    According to official estimates, 300,000 were also injured, 1.3 million displaced, 97,294 houses destroyed and 188,383 damaged in the Port-au-Prince area and in much of southern Haiti. This includes at least 4 people killed by a local tsunami in the Petit Paradis area near Leogane. Tsunami waves were also reported at Jacmel, Les Cayes, Petit Goave, Leogane, Luly and Anse a Galets.

  • 6: Damghan, Iran, Dec. 22, 856

    Magnitude not known, about 200,000 deaths.

    This earthquake struck a 200-mile stretch of northeast Iran, with the epicenter directly below the city of Demghan, which was at that point the capital city. Most of the city was destroyed as well as the neighboring areas. Approximately 200,000 people were killed.

  • 7: Haiyuan, Ningxia , China, Dec. 16, 1920

    7.8 magnitude, about 200,000 deaths.

    This earthquake brought total destruction to the Lijunbu-Haiyuan-Ganyanchi area. Over 73,000 people were killed in Haiyuan County. A landslide buried the village of Sujiahe in Xiji County. More than 30,000 people were killed in Guyuan County. Nearly all the houses collapsed in the cities of Longde and Huining. About 125 miles of surface faulting was seen from Lijunbu through Ganyanchi to Jingtai. There were large numbers of landslides and ground cracks throughout the epicentral area. Some rivers were dammed, others changed course.

  • 8: Ardabil, Iran, March. 23, 893

    Magnitude not known, about 150,000 deaths

    The memories of the massive Damghan earthquake (see above) had barely faded when only 37 years later, Iran was again hit by a huge earthquake. This time it cost 150,000 lives and destroyed the largest city in the northwestern section of the country. The area was again hit by a fatal earthquake in 1997.

  • 9: Kanto, Japan, Sept. 1, 1923

    Kanto Damage
    Hulton Archive  /  Getty Images
    1923: High-angle view of earthquake and fire damage on Hongokucho Street and the Kanda District, taken from the Yamaguchi Bank building after the Kanto earthquake, Tokyo, Japan. (Photo by Hulton Archive/Getty Images)
    7.9 magnitude, 142,800 deaths.

    This earthquake brought extreme destruction in the Tokyo-Yokohama area, both from the temblor and subsequent firestorms, which burned about 381,000 of the more than 694,000 houses that were partially or completely destroyed. Although often known as the Great Tokyo Earthquake (or the Great Tokyo Fire), the damage was most severe in Yokohama. Nearly 6 feet of permanent uplift was observed on the north shore of Sagami Bay and horizontal displacements of as much as 15 feet were measured on the Boso Peninsula.

  • 10: Ashgabat, Turkmenistan, Oct. 5, 1948

    7.3 magnitude, 110,000 deaths.

    This quake brought extreme damage in Ashgabat (Ashkhabad) and nearby villages, where almost all the brick buildings collapsed, concrete structures were heavily damaged and freight trains were derailed. Damage and casualties also occurred in the Darreh Gaz area in neighboring Iran. Surface rupture was observed both northwest and southeast of Ashgabat. Many sources list the casualty total at 10,000, but a news release from the newly independent government on Dec. 9, 1988, advised that the correct death toll was 110,000. (Turkmenistan had been part of the Soviet Union, which tended to downplay the death tolls from man-made and natural disasters.)

Discuss:

Discussion comments

,

Most active discussions

  1. votes comments
  2. votes comments
  3. votes comments
  4. votes comments