Ko Samui Properties - Earthquakes in Koh Samui

The recent earthquakes on the west coast around Phuket caused a great deal of concern, not just because of the potential to create a tsunami but because of the damage an earthquake can instigate. Earthquakes themselves do not always create damage apart from where cracks appear in the ground. The main damage is to buildings and other structures such as bridges and elevated highways as well as causing landslides and rock falls. Phuket is susceptible due to its location on the west coast, not only because of its proximity to the Andaman fault line but also because it lies adjacent to the Khlong Marui fault line which runs immediately to the east of the island in a north-easterly direction and it was along this fault line that the most recent earthquake occurred. This fault line continues across the peninsular and runs between Koh Samui and Chumpon but is not considered by the Thai Department of Mineral Resources to be active in this region and the USGS records a slip rate of 0.01mm per year and earthquake probability of once in 127,000 years.


People live in earthquake areas all round the world and experience earthquakes on an almost daily basis. Japan and the West Coast of the USA are prime examples. Thailand is not regarded as being at major risk from earthquakes although there are many fault zones throughout the country, mostly in the north and north-west. There are no building codes in force to my knowledge which are relevant. However, I am attending a seminar in Bangkok in June which may tell me more. Nor is there advice on what to do in the event of an earthquake.

In San Francisco the telephone books have pages of information and advice on the actions to take and not to take in the event of an earthquake. One piece of advice was not to run out into the street as you may well be hit by falling debris. For more information of what to do in an earthquake follow this link. Buildings in California are built to very strict codes. I had a 35 storey office building in my management portfolio and during the Loma Prieta 6.9 earthquake in 1989 which destroyed the Marina District and a number of highways with 63 deaths, we only suffered USD 10,000 of damage with one window blown out and some minor cracking to walls requiring re-painting. This was due to correct design and construction which mitigated damage but it costs money and a balance must be sought between prudence and economic reality.

Koh Samui does not have a high earthquake risk. With one exception all the earthquakes in the region over the last ten years have been to the west of the peninsular. The one exception was on 7th October 2006, 42 km off Prachuap Khiri Khan, at a depth of 10km and magnitude 5.0 on the Richter scale. This would lie on the northern end of the Ranong fault line which runs in a south-westerly direction across the peninsular and to the west of Phuket.

As unpredictable as nature can be, it seems highly unlikely that Koh Samui will be affected by earthquakes except possibly at a great distance. However, the question remains – can Koh Samui be affected by a tsunami? That is the subject of next month’s Newsletter.

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