Ministry to revise geographical control points


The frequency of earthquakes in South Korea rose sharply this year, following the global trend in the number of tremors, the weather authorities said Thursday.

The Korean Peninsula experienced 45 quakes ― 17 times on land and 28 times in nearby seas ― from January to September, the Korea Meteorological Administration said in a report.

The figure is up from last year’s 30 and the second highest to 47 quakes in 2009, the record high since the KMA started measurement. The annual average so far is 32.6 times.

Eight of them were greater than 3.0 in magnitude and six were detectable by humans, the administration said. The strongest was a 4.1 magnitude-quake in the sea 16 kilometers off Baegnyeong islands in June.

In the case of land quakes, the majority took place in North Korean territories followed by Daegu, then Daejeon. For quakes in the sea, the West Sea was the most affected, followed by East and South Seas.

According to the U.S. Geological Survey, the number of quakes greater than 5.0 in magnitude around the world from January to September was 2,082, about 1.74 times more than the annual average between 1978 and 2010. Of them, 17 were measured at greater than 7.0 in magnitude.

Experts believe that the latest earthquake which devastated Japan and its aftershocks also had a strong impact on Korea. The Japanese disaster and more frequent earthquakes have pushed the Korean Peninsula a little less than an inch east, the weather agency said.

Earthquakes have also made the Korean government revise geographical control points nationwide. The Ministry of Land, Transport and Maritime Affairs said it will spend 65.8 billion won over the next five years on revising the points.

Control points are essential in imaging georeferencing, which establishes location in terms of map projections or coordinate systems. Examples include establishing the correct positions of an aerial photograph within a map or finding the geographical coordinates of a place name or street address.

A minor change could cause enormous differences in the outcome of measurements, construction and many other geographical operations.

According to the National Geographic Information Institute’s National Base Network System, the most recent Japanese earthquake moved the peninsula an average of 2.3 centimeters east. Also, the easternmost Korean islets of Dokdo in the East Sea moved 5.4 centimeters east.

By Bae Ji-sook (baejisook@heraldcorp.com)