Nuclear Boy

 

The entertaining anime cartoon above is apparently being shown to Japanese children. It is supposed to explain what is happening at the Fukushima nuclear plant. I learned a lot. There is definitely more information here than in the official government press releases. My brother lives in Tokyo but like most Japanese has not chosen to leave home over the dangers which the nuclear incident may portend.

9.0 Earthquake and Tsunami hit Japan

CNBC host Larry Kudlow proudly displays those "ugly American" attitudes which are so in demand today in our broadcast media. My brother lives in Japan, so perhaps I am overly sensitive. My brother is fine but he did say that this is the worst earthquake that he has experienced. He has lived in Japan for at least 25 years now, since the late 1980's.

Earthquake shakes southern Japan

3.2 M Earthquake in TN, GA

A minor earthquake with a 3.2 moment magnitude occurred about 11 AM this Saturday, August 1st in the mountains of Tennessee and Georgia. The epicenter was near Ducktown, Tennessee, about 55 miles east of Chattanooga. Although I did not feel any effects down here in south Georgia, an intensity map prepared by the USGS shows light to moderate shaking in the northern suburbs of Atlanta.

Earthquake on South Island, NZ

An earthquake occurred at 9:22 PM (9:22 AM GMT) on the evening of Wednesday, July 16th in the Fiordland region of southern New Zealand. At this writing , the earthquake's moment magnitude is reported as 7.6 by the USGS but as 7.8 by the New Zealand's Institute of Nuclear and Geological Sciences. Fiordland is near the southern tip of South Island, where the Australian Plate moves to the northeast at a rate of 35-45 mm/yr relative to the Pacific plate. The yellow area in the above "beach ball" pattern shows the predominantly eastward component of the current thrust within the northeastward plate movement.

The tremor lasted at least a minute and was felt as a rolling motion across New Zealand's South Island, according to the BBC. New Zealand issued a tsunami warning for a string of its coastal towns and cities, but later cancelled it. A tsunami was detected in the Tasman Sea, heading towards the southeast coast of Australia. About an hour after a tsunami warning was issued, Australian officials downgraded it to a "small boat alert" and there was little or no evidence for coastal flooding as a result of the quake.

Crandall Canyon Mine in EOS

I recently renewed my subscription to EOS, the weekly newsletter of the American Geophysical Union. An article on the Crandall Canyon Mine collapse appeared in the issue published back on August 21st. Staff writer Randy Showstack reports the consensus view among seismologists, which I previously summarized here in this blog, that the 3.9 magnitude event was probably caused by an underground cavity collapse rather than a tectonic earthquake.

Showstack interviewed a number of geophysicists, including Douglas Dreger of the Berkeley Seismological Laboratory (BSL) at the University of California, Berkeley. Dreger emphasized that the pattern of "first motions" shown in the seismographs is not the alternating pattern that would indicate an earthquake. Instead, Dreger said, the ground moved down initially. James Pechman, research associate professor of geology and geophysics at the University of Utah, also argues for an underground collapse due to the fact that “all the P wave first motions in the University of Utah network for this seismic event were downward or dilatational. That is not definitive by itself, but in these areas with lots of coal mine–induced seismicity, when we see all downward first motion, we expect a collapse event in the mine.”

Showstack concludes his piece by noting that Robert E. Murray, co-owner of the Crandall Canyon Mine, was continuing to attribute the mine collapse to a natural
earthquake. Murray's interpretation, as Showstack notes, is at variance with the consensus of geophysicists who have inspected the seismological records from the event.

Crandall Canyon Coal Mine Collapse

I had my suspicions about this one from the first day of reporting, which I guess was last Monday. That would have been the day of our convocation at VSU, where I am now teaching on a one-year temporary appointment.

Geophysicists with both the University of Utah and the U.S. Geological Survey were already saying late Monday that the event recorded on seismographs was the collapse itself, rather than an earthquake which triggered it. I know of a similar collapse event which is often mistaken for an earthquake in the seismological record for the anthracite coal fields of Pennsylvania. A "first motion" or "moment tensor" analysis using seismographs from throughout the western United States has now been completed by a team at the Berkeley Seismological Laboratory. The source mechanism for the August 6 seismic event is most consistent with the collapse of an underground cavity.

Robert Murray, who owns part of the mine in which the six miners are now entombed, continues to question the findings of geophysicists which have been reported by the press. For an excellent analysis of the mining methods and rock properties that played a role in this disaster see the recent post at The Oil Drum.

Strong Earthquake Rocks Guatemala

The U.S. Geological Survey gives a magnitude of 6.8 and has coordinates for the epicenter, indicated by the star on the map above. Initially, the depth of the focus was estimated at 64.8 km but that has now been revised to 23 km. That is a shallow earthquake, one of the yellow balls. Most of the earthquakes this close to shore have been deeper and not as strong, shown as green balls on the map.

Earthquake in southern England? ? ?

Both the BBC and the Daily Mail are reporting that an earthquake with a Richter magnitude of 4.7 struck in the Dover Straits at 8:18 AM local time (3:18 EDT). According to the BBC story,

The British Geological Survey has measured the epicentre as being approximately 8.6 miles (14km) south of Dover, out in the English Channel. Dr Roger Musson, of the British Geological Survey, said the earthquake was "not exceptionally large" for Britain.

More than 100 emergency calls were made to the Fire and Rescue Service in Kent, according to the story in the Daily Mail. In addition to minor structural damage, gas smells have been reported. A gas company spokesman quoted by the BBC remarked that the smells may be from natural gas brought up by the earthquake although the company is also checking their lines for hazardous ruptures.

UPDATE (11:15 EDT): The British Geological Survey is reporting a local magnitude (ML) of 4.3 for the quake and notes that this is the largest earthquake in southern England since a magnitude 4.4 ML event in 1950. Significant earthquakes also struck the Dover Straits in 1776, 1580, and 1382, the latter had an approximate magnitude of 5.7 ML and reportedly caused damage in London. Earthquakes of this size occur in mainland UK roughly every 7-8 years and are somewhat more common in offshore areas.

The following information is currently being reported on the BGS webpage:

DATE : 28 April 2007

ORIGIN TIME : 07:18 10.0s UTC

LAT/LONG : 50.97º North / 1.38º East

GRID REF : 636.9 kmE / 124.4 kmN

DEPTH : 5.0 km

MAGNITUDE : 4.3 ML

INTENSITY : 6 EMS

LOCALITY : Dover Straits, 14km south of Dover

Earthquake in Georgia!

Late in the evening on Tuesday, March 14th, a small earthquake shook parts of east Georgia. According to Pam Tucker, the Emergency Services Director for the county which includes most of Augusta, citizens reported hearing a loud boom and feeling vibrations at around 11:20 PM.

The star on the above map shows the epicenter located by the U. S. Geological Survey (USGS) using seismographs in the surrounding region. While the Atlanta Journal-Constitution reported a 1.8 Richter magnitude, the USGS has a 2.1 magnitude. The USGS also estimates a 5 km depth for the focus, the point in the crust where the seismic energy originated. There are old thrust faults in this area, mostly inactive although they do sometimes produce minor tremors as apparently occurred Tuesday night.

Sumatra Earthquake

According to CNN, at least 70 people are dead as a result of an earthquake with a Richter magnitude of 6.3 followed by several very strong aftershocks on the island of Sumatra in Indonesia. The epicenter is located on the western side of the island according to the above map prepared by the U. S. Geological Survey.

It is a little early for anything to be known about the tectonic mechanism that was responsible for the earthquake, although several countries collaborate in the investigation of every large event in this sensitive region at the intersection of three major tectonic plates. A "focal mechanism" should be posted within the next day or two by the Japanese. The Indonesian Meteorological and Geophysical Agency reports a somewhat lower Richter magnitude of 6.0.