Little earthquakes

[iainiain101]

After the last 6.4 one in Chiang Rai that most of us felt in Chiang Mai,  I started watching the earthquake website http://www.seismology.tmd.go.th/en/local.html

 

There have been dozens more in Chiang Rai, some 4 plus on the richer scale, but today I saw that there was one in Tak. Not seen one there before, and we seem to be half way between Tak and Chiang Rai on almost a straight line. cause for concern?

[naboo]

lots of little ones are good, the pressure on the fault is being released gradually.

Without the little ones we'd have the occasional big one.

[worgeordie]

Chiang Mai is at the end of the Himalayas mountain range,and as 

the Indian sub Continent is still pushing North ?,thats what causes 

 the quakes in this area i believe.

regards worgeordie

[kaptainrob]

We're in what's known as a 'convergence zone' - between the Indian and China tectonic plates.  As Wg says, these plates grind & push against each other and cause movemment along minor fault lines [such as Fang-SanKampheang-Lamphun's - "Mae Tha"].  There are many minor faults in this northern region as you can see here:-

Edited August 3, 2014 by kaptainrob

[Sparkles]

Interesting ...surprised Bangkok is not shown on that map as about 8 years ago my wife had to run down 19 floors of a 21 floor office tower as the building was in "sway" mode.

 

Emergency drills seem not to be held in Bangkok as maybe tremors are unusual. After evacuation of the building of course they all stood outside without thinking bits of the building could fall on top of them !

 

 

[kaptainrob]

Bangkok is built on a river delta, over mud which conducts shock waves very well ... Mexico City and Christchurch [NZ] have similar characteristics.  Major faults and subsequent tremors may be 10's or 100's of km's away, horizontally or vertically, and feel very powerful on the 19th floor of a BKK highrise, yet pass unnoticed at ground level.

[Longtooth]

Bangkok is built on a river delta, over mud which conducts shock waves very well ... Mexico City and Christchurch [NZ] have similar characteristics.  Major faults and subsequent tremors may be 10's or 100's of km's away, horizontally or vertically, and feel very powerful on the 19th floor of a BKK highrise, yet pass unnoticed at ground level.

 

Liquefaction.  Larger damage in SF, Cali down on the filled areas, as opposed to higher, firmer ground,  some years ago.  Interesting that both Chiang Mai and Chiang Rai have little red lines pointing at them on the fault map.