Sunday, April 10, 2011

A Period of Giant Earthquakes?

Richard Aster is a geophysicist at the New Mexico Institute of Mining and Technology, and he is also the president of the Seismological Society of America. To say he knows a bit about the makeup of earthquakes is an understatement. And he's been studying with great interest the major earthquakes of the past several years.

The official definition of Giant Earthquakes are those that register 8.0 or higher on the Richter Scale. Historically, temblors of that magnitude are relatively rare, when compared with the total number of all earthquakes. If we look back to 1900, we can study the statistics. According to Aster, we may now be in the middle of a new age of large earthquakes. Take a look at the numbers and maybe you'll see what he is seeing.
  • 1903 — 8.3 Greece
  • 1906 — 8.8 Ecuador
  • 1906 — 8.2 Chile
  • 1918 — 8.2 Philippines
  • 1920 — 8.6 China
  • 1922 — 8.7 Chile
  • 1923 — 8.5 Russia
  • 1933 — 8.4 Japan
  • 1934 — 8.1 Nepal
  • 1943 — 8.2 Chile
  • 1945 — 8.0 Pakistan
  • 1946 — 8.1 Japan
  • 1948 — 8.1 Philippines
  • 1950 — 8.6 China
  • 1952 — 8.1 Japan
  • 1952 — 9.0 (a really big one) Russia
  • 1957 — 8.1 Mongolia
  • 1959 — 8.0 Russia
  • 1960 — 9.5 (most powerful quake ever recorded) Chile
  • 1964 — 9.2 (another monster) Alaska
  • 1965 — 8.2 Indonesia
  • 1966 — 8.2 Peru
  • 1968 — 8.3 Japan
  • 1970 — 8.0 Colombia
  • 1971 — 8.0 Papua New Guinea
  • 1976 — 8.0 Philippines
  • 1985 — 8.0 Mexico
  • 1995 — 8.0 China
  • 1995 — 8.0 Mexico
  • 1996 — 8.2 Indonesia
  • 2000 — 8.0 Papua New Guinea
  • 2001 — 8.4 Peru
  • 2003 — 8.3 Japan
  • 2004 — 9.3 (monster that killed nearly 300,000) Indonesia
  • 2007 — 8.1 Solomon Islands
  • 2007 — 8.0 Peru
  • 2007 — 8.5 Indonesia
  • 2009 — 8.1 Samoa
  • 2010 — 8.8 China
  • 2011 — 9.0 (another monster) Japan
So since the year 1900, there have been 40 earthquakes that registered 8.0 or higher on the scale. During that period, 5 of the temblors were measured a 9.0 or higher. 

What's interesting is that there seems to be a pattern — for example, during the period from 1950 to 1967 there was a spike in large earthquakes. Then there are lulls, then heightened activity again during certain periods. One pattern of interest is that none of the 9.0 or greater quakes occurred in the first half of the 20th century. All 5 of them happened after 1952. And two of them in just a 7-year period. And, during that same 7-year period, there have been 7 Giant Earthquakes (and we're not finished with this year yet) — something that has never happened before. 

Are we entering a period of Giant Earthquakes?  The statistics are very interesting. 

1 comment:

  1. We're due, I'm more ready to deal with such than most here. Bring it on, it's getting sort of boring around here.

    May you live in interesting times.

    ReplyDelete