Thursday, February 24, 2011

Shallow Quakes associated with the New Madrid Fault & BP's Mega Oil Spill.

Shallow Quakes associated with the New Madrid Fault & BP's Mega Oil Spill.
  • by BK Lim (23 Feb 2011) email:
Is there a common factor between the quake off Fort Morgan on 18 Feb 2010 and the recent swarm of quakes occurring in the vicinity of the New Madrid Fault zone? You are right if the BP Mega Oil spill and the Deepwater Horizon blowout on 20 April 2010 comes to mind.

They are all quakes similar to the disastrous 22 Feb 2011 quake that occured close to Christshurch in New Zealand. Their shallow epicentres are off the main tectonic (or intra-plate) fault lines. There are significant differences though, especially in magnitude and tectonic plate settings. The recent NZ disaster was more devastating than an earlier quake 11 times more powerful with its epicentre on the plate margin.

Since the 2Aug 2010 quake at Louisiana, we have been warning of more occurrences of such shallow low magnitude quakes. See figure 145-1 which shows some of the hidden series of NW-SE strike-slip fault lines typical of intra-plate movement. The fault chart (prepared in August and updated only with annotations) was only published on 10 Nov2010, Update On BP Rigs Location & the Fault Connection. The consequence of the continuing corosive erosion along these faults by leaking hydrocarbons from deep reservoirs (not only from the Macondo prospect) is the release in stresses between the upper and lower crust; resulting in shallow quakes of generally low magnitude. This was mentioned in a recent article, first written on 14 Feb and updated 20 Feb 2011.

For millions of years, the south-eastern part of the North American tectonic plate (south-east of the New Madrid Fault line) has been thrusting in a north-easterly direction while the western half of the plate has been moving south along the San Andreas fault line. This is the main reason for the present gulf seabed morphology.
The resultant torsion tension is reflected by the fault pattern illustrated in a previous article BP's Rigs Location & Fault Connection. Besides lateral stresses, vertical stresses also developed between the upper and lower section of the tectonic blocks due to differential upper and lower slide movement. The abnormal occurrences of hundreds of shallow and low magnitude earthquakes since the Macondo blowout are the direct consequence of the continual release of these pent-up stress zones. FEMA recently sent out RFI (request for information) to identify vendors for the emergency supply of food rations, various fuels and hydration in support of disaster relief efforts based on a catastrophic disaster event within the New Madrid Fault system for a survivor population of 7 million to be utilised for the sustainment of life during a 10-day period of operations. Is FEMA having privileged information of an impending disaster in the New Madrid Fault area, 9 months after the BP's Mega-oil Spill disaster?
~~~end of quote ~~~~

What is the area extent of these continuing leakages of hydrocarbons along these faults , vaporisation of methane hydrates due to warming effect of these leaking hydrocarbons and rapid mass depletion caused by continuing sub-seabed erosion? Judging by the number of reported quake-swarms, we are pretty close to the point of no return if we have not passed that point yet.
So far the quakes had been low magnitude between 2 to 4 on the Richter Scale. FEMA is expecting a major quake disaster similar to the recent Christchurch Quake in New Zealand. As we have seen, the shallow quakes are more devastating than a deep one at the base of the crust. The New Madrid Fault is an intra-plate tectonically stressed zone. It behaves very differently from the tectonic plate margins.
Since these shallow intra-plate quakes had been unleashed by the drilling and blowouts at the Macondo prospect, it makes sense to monitor closely the seafloor and the continental shelf edges. Mapping the gas vents in the vicinity of these faults and shelf edges would go a long way to making accurate predictions of what to expect in the vicinity of the New Madrid Fault zone. More powerful need not necessarily be more devastating but one thing for sure, the disaster has not ended yet despite what you have been told. Christchurch was hit by a hidden fault (???)

New_Zealand_Earthquake_Science By ALICIA CHANG, AP Science Writer–Tue Feb22, 6:10pmET
LOS ANGELES – The latest New Zealand earthquake was a deadly combination of distance, depth and timing. While weaker than the one that rocked the area last September, it did more damage and cost lives, primarily because of its location. Tuesday's magnitude-6.3 quake was centered about 3 miles from the populated hub of Christchurch, toppling buildings, killing dozens and trapping others. It was also only about 3 miles deep and occurred during the middle of a workday when commercial buildings were filled with employees.The jolt "is squarely beneath the city itself," said seismologist Egill Hauksson of the California Institute of Technology. "All the old historic buildings are being shaken more violently than they were built to withstand." Scientists classified it as an aftershock of the powerful magnitude-7 that struck last Sept. 4.
No one died in that early morning quake — which was 11 times stronger — mainly because it was centered farther away, about 30 miles west of the city center. It was also twice as deep as Tuesday's aftershock. Shallower quakes tend to be more damaging.

1 comment: