Quakes 'a concern'

Quakes 'a concern', say Thai scientists
By Janjira Pongrai
The Nation

Several fault lines in Thailand have destructive potential, say geologists
A major fault line in Burma that caused Thursday's earthquakes is connected to a fault line in Thailand and both possess "similar seismic behaviours", a Chulalongkorn University geologist said yesterday.
"The quakes in Burma have caused us concern," said Assoc Professor Panya Jarusiri, noting the greater length of the Mae Chan fault line in Thailand, at 250 km, compared to the 150km length of the Mengxing fault line in Burma.
"What is a relief is that the quakes are inland and would cause less devastating effects than those occurring on sea beds," he added.
Asked of the chances of the Mae Chan fault line causing earthquakes in the future, Panya said: "The chances are there, but we can never tell when. A fault like Mae Chan yields the possibility of one quake in a 600year period, at a possible size of 6.07.0 on the Richter scale."
There are two other "locations of concern" in Thailand, Panya said: the Three Pagoda fault line in Kanchanaburi and Ratchaburi provinces and the Khlong Marui fault in the southern provinces of Surat Thani, Krabi and Phang Nga. Both fault lines regularly cause small earthquakes of 2.03.0 magnitude, with the greatest possible quake being 6.0.
Professor Thanawat Jarupongsakul, another CU geologist, said Thursday's quakes stemmed from fault lines connected to others in China and Laos that have caused a total of 27 quakes of magnitude 6.07.0 since 1973.
The greatest quake in 1988, at 7.1 magnitude in Sichuan, caused 700 deaths, while another three years ago was 6.3.
Of 13 fault lines in Thailand covering 22 provinces, there are four groups of active frontlines: those at Sri Sawat and Three Pagodas Pass in Kanchanaburi province; at Sakaing in the west; and the Khlong Marui fault covering Surat Thani, Krabi and Ranong.
Of the 22 provinces, 11 are in the North, six are in the South, three are in the West and two are in the Northeast.
Despite the tremors felt in Bangkok, the jolts have not impacted or damaged highrise buildings because their foundations are deep below the capital's top layer of soft clay, Thanawat said.
History of quakes in Thailand
The first recorded earthquake was a major quake in 1015 in presentday Lampang province, which caused much of the ancient kingdom of Yonok Nakhon to collapse into a huge crater, the remains of which are now just a large pond.
A moderate quake in 1545, in the heart of the Chiang Mai kingdom, caused heavy damage to property.
In 1935, a 6.5magnitude quake was reported in Nan and a 5.9 quake was reported in 1975 in Tak's Tha Song Yang district.
In 1994, a 5.1Richter quake in Phayao caused damage to buildings and schools.

-- The Nation 2011-03-26