A M 7.5 earthquake hit the coast of the Island of Sulawesi in Indonesia at 17:02:31 UT today. The closest town was Gorontalo. The BBC news channel reports no casualties or damage and an initial Tsunami alert was quickly lifted. The area was subjected to aftershocks of M5.6 at 17:34 UT and M 5.5 at 18:20 UT.

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A M 6.3 earthquake, at a depth of 16 Km in a remote part of China, no reports of any damage or casualties.

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  A small event in Scotland, but importantto Dunblane High school (DUNHS) as it was the first event that they recorded! 

Although Uk falls in the shadow zone,the surface waves from this event can be seen. This event occours in a same area as the M 6 event north of Papua New Guinea on the 28th October. The PAUL helicorder trace shows the arrival of waves from an event between 00:30 and 00:40 on 1st November 2008 Checking out the KEYW screen on IRIS there also appears to be an arrival at this time, it would appear to be the surface waves from the M 5.1 aftershock in Pakistan at 23:59:53 on 31st October, or was it someone trick or treating?? comments?

This is the first of three articles about charged particle motion in electromagentics fields and the earths magnetic field. The articles will include simple demonstrations built using the matlab clone scilab and the visualisation tool IBM Open data explorer, both of these are open source applications. The first article  will describe a simple scilab based application for modelling charged particle motion. The Lorentz force can be used to model a wide range of systems and phenomena including

• Motion of particles in colliders and their detectors e.g. the CERN Large Hadron Collider
• Understanding the solar interior and atmosphere
• Understanding  the charge particles in the ionosphere e.g. the borealis
• Confinement of plasmas  for experimental fusion reactors
• Focusing of beams for electron microscopy

The Lorentz force is the force on point charges due to electric and magnetic fields the elctric field gives rise to a linearly increasing force relationship between the charge and the elctric field intensity. The force generated through the magnetic field is such that it is perpendicular to the plane formed by the particle velocity vector and the magnetic field. This explains the action of the vecotor cross product term.

The cross product term can be undersood from the relativistic nature of the elctromagnetic interaction. It is important to remember that the relativistically covariant Maxwell equations and the special theory of relativity enable us to understand the unified nature of the single electromagnetic interaction. When the lorentz transformations are applied to the electric field we have a cross product relationship between the velocity of the particle and the magnetic field it therfore appears that the magnetic interaction is generated by a relativistic effect, an article in the links provides a good description.

The scilab script uses the lorentz force to update the position of a particle in a constant and uniform electromagnetic field. The equations of motion are solved using a simple Euler integration step. When executed, the script  starts a number of dialogs in turn requesting the user to

• Define the initial velocity
• Define the b field
• Define the e field
• Provide a tile for the plot
• The plost is drawn
• The user is asked if they want to save the plot, if yes and OK are clicked a file save dialog opens.

The particle mass and charge are hard coded at the start of the script but can be altered if the user requires. Not surprisingly there is a lot of information about the lorentz force and charged particle motion, including some interesting video content on utube, one such link in the useful links section below

 

Useful Links

Scilab script requires the lorentz force function file

Matlab script requires the lorentz force function file

Scilab home page

IBM Open data explorer

Wikipedia on Lorentz force

Wikibook on the lorentz force

Science world info about the lorentz force

Article about relativistic transformation of electromagnetic fields

Utube demonstration of Lorentz force

12 hours after eth damaging Mw6.4 event in Pakistan a second event occurred

An earthquake with a magnitude of 6.4 has killed at least 135 people and injured hundreds of others in the southwest of Pakistan. The epicentre of the event is located about 45 km north of the town of Quetta. Many houses in the vicinity collapsed or were destroyed by landslides resulting from the tremor. It is estimated that around 15,000 people may have been made homeless. Pakistan's second most damaging earthquake occurred near Quetta in 1935, killing almost 30,000 people. Last night's event locates approximately 740 km southwest of a magnitude 7.7 earthquake which occurred in north-eastern Pakistan on 8 October 2005, killing around 80,000 people. Further information, seismograms of the event and a seismicity map of the area can be found at the following link:- http://www.earthquakes.bgs.ac.uk/recent_events/world_special/pakistan_28

Scispace seem to have changed their website and made us lose all our images, this is just to see if new posts can put up images

 

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Didn't feel anything myself but the trace was quite clear on the Helicorder.

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