Recent Events in our World
Check out our seismograph - updated every minute. The US Geological Survey provides up to date (at least up to the last hour) information on recent earthquakes around the world. VolcanoWorld provides the best up to date information on volcanic activity around the world.
A busy day in the seismic lab
Six earthquakes in one day were recorded on the Acadia seismograph. At the top of the day's record are the two M8 earthquakes west of Sumatra, followed by an M6 earthquakes west of Oregon and in the south of Mexico. Overwhelming the record is trace from an M7 tremor in the Gulf of California, and if you look carefully you will see the record of a small M4.5 tremor 200 km south of Yarmouth. The strength of the record depends on the strength of the earthquake and how far away the earthquake occurred.
[Click here for a larger image without the labels.]
12 April 2012
The winter that isn't? It depends on where you are.
Many people are commenting on the winter that isn't this year. We have had a few short cold spells, but many mild spells, often accompanied by rain, and as a result no deep snow (although did you forget about that 42 cm snowfall back in November, that melted away in 15 degree rain two days later?) All across Canada and the USA it seems people are remarking on the mildness of the winter. Is it true? It depends where you are
The National Climatic Data Center compilation of temperature anomalies shows that North America did indeed experience an abnormally warm January - up to over 5 degrees above normal in the centre of the continent. However, Alaska was 6-8 degrees below normal, and central Asia similarly had a cold month. Recent weather reports from Europe have recorded record cold from England to Turkey, with deep snow along the Mediterranean, so no doubt a February compilation would look very different. What the anomaly map shows is a normal winter - cold in some places, warm in others, although the degree of warming in the more northern areas might be remarkable.
16 February 2012
Virginia Earthquake, 23 August 2011
In the afternoon of 23 August, millions of people on the US East Coast, and parts of Canada witnessed one of the most severe earth tremors in the eastern half of the continent in over 100 years. The epicentre was in Virginia, and minor structural damage was reported in cities like Washington, Baltimore, Norfolk and Richmond. Ground shaking was felt as far away as New England and Ohio, and even in Toronto and Fredericton, buildings located on fill that amplifies the seismic waves had noticeable effects - water sloshing in coolers, pictures moving on walls, cords rattling against window frames. The seismograph at Acadia showed an impressive response:
The small tremor at 0615h was a 5.3 earthquake in Colorado; the 5.8 Virginia earthquake is at about 1755h, only 4 minutes or so after it happened in Virginia. The initial P and S waves are clearly visible, and the L waves continued for over half an hour.
24 August 2011
Sendai Megathrust Earthquake, Japan
The devastating Sendai earthquake has provided some remarkable statistics. At magnitude 8.9, it is certainly in the top 10 for earthquake magnitude, likely in the top 5. For the first time in recorded history two top 10 earthquakes have occurred in successive years (the other being the Concepcion earthquake, Chile, last March). The US Geological Survey reported that at least one GPS station has moved 2.5 m to the east, consistent with observations of the Japanese Geospatial Information Authority that shows a large area of Honshu has been displaced. It has been estimated that the earthquake has shifted the Earth on its axis by as much as 10 cm. The earthquake appears to have caused a rupture along an area about 400
km long by 160 km wide, as the Pacific plate slipped more than 18 metres under the Okhotsk extension of the North American plate, which extends as far south as Tokyo.
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First motion observations reveal two possible fault planes, one
dipping steeply to the east and one at a shallow angle to the west. The
latter is consistent with a shallow-dipping subduction zone thrust fault
system.
The extent of the large zone of slip is evident on the map which shows the location of the main earthquake (yellow) and the aftershocks received in the subsequent 30 hours. |
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The Acadia seismograph recorded the earthquake, when the first motions
arrived here at 4.58 UT (1.58 AT). Note also the foreshock at 17.25 UT -
this was a magnitude 7.2 event. 12 March 2011 |
Earthquakes in New Zealand
The city of Christchurch on the South Island has been rocked again by a significant earthquake. Most Geology students know that New Zealand sits on the Pacific-IndoAustralian plate boundary, and is tectonically active, but that most of the seismic activity is focused on the Alpine Fault, 150 km west of Christchurch. The city sits on the broad Canterbury Plains, river outwash from the rapidly rising Southern Alps. Just south of the city sits the Banks Peninsula, a pair of deeply dissected basaltic shield volcanoes, active 10 million years ago.
[Click for larger image.]
The September 2010 earthquake occurred well to the west of the city. The February 2011 earthquake, however, had an epicentre on the southern edge of the city, adjacent to the Banks Peninsula. Even though it is commonly reported as an "aftershock", and was a weaker earthquake, far more damage was done because of proximity to the city, the magnifying effect of the soft sediment upon which the city is built, and possible reflections of seismic waves of the hard mass of the volcanic rocks of the Banks Peninsula.
See the Highly Allochthonous blog for lots of detail about this event.
2 March 2011
2010 - the hottest-equal year in recorded history
The numbers have been crunced by NASA and by the National Oceanic and Atmospheric Administration (NOAA) and show that 2010 was tied with 2005 and nearly tied with 1998 as Earth's warmest year in recorded history (since 1880). In 2010 the average global temperature was 0.62°C above the 20th century average. Many subsets of the data also demonstrate the exceptional heat of 2010: the Northern Hemisphere's warmest year on record, the Southern Hemisphere's 6th warmest, the 2nd warmest year on land masses, the 3rd warmest year on oceans. These records are all the more significant for at least on two counts, major forces were at work to ensure 2010 would not be especially warm - the sun is currently at the low point in its solar output (sunspot) cycle, and the Pacific Ocean is experience a moderate-high level of La Niña conditions.
The La Niña effect can be seen by the broad cool region extending
across the southeastern Pacific, but the eye is drawn to the hot red
colours across most of the Northern Hemisphere (remember those Russian
heatwaves last summer?) and the extreme warmth of eastern Canada,
corresponding to open ocean conditions even into January, 2011 in parts
of the Arctic.
Since so much warming occurred in what should have
been an abnormally cool year, one wonders what the Earth will do when
the sun's output increases in 2014-2015, especially if that coincides
with an El Niño?
For more details, see Jeff Masters' blog.
17 January 2011
For previously listed events in 2010, please go to the Recent Events archive.