Typhoon Megi

Landfall | Summary
Posting Date: September 27, 2016, 10:30:00 AM

For a third time within two weeks Taiwan is being battered by a major storm. Typhoon Megi made landfall in northeastern Hualien County at about 1:30 p.m. local time on Tuesday, September 27, and its impacts will be felt for at least 12 hours as it passes across the country. With so much precipitation having fallen in recent days, the additional heavy rain delivered by Megi is likely to cause life-threatening floods and landslides. The storm is expected to weaken and make a second landfall in China, to the northeast of Hong Kong, on Wednesday.

Four deaths and hundreds of injuries have been reported in Taiwan so far, and more than 3 million homes have lost power, the second largest number on record. More than 11,000 people have been evacuated, almost 3,000 are in shelters, and 35,000 households are without water supply. Roofs have been torn off buildings, and waves reportedly reached four stories high in the coastal city of Hualien.

Track forecast for Typhoon Megi at 12:45 UTC, September 27, 2016. (Source: JMA)

Typhoons in Taiwan

The most active period for typhoons is June through October, with a peak in August and September. An average of two typhoons make landfall in Taiwan every year, with another three coming close enough to land to cause loss. Taiwan’s eastern coast, where typhoons make landfall and heavy wind damage tends to occur, is relatively unpopulated. Typhoons then typically weaken rapidly upon interaction with the formidable central mountain range, which rises quickly from sea level to elevations as high as nearly 4,000 meters within 50 km of the coast. As a result, the greatest threat the country faces from typhoons is usually rain-induced flooding as storm systems pass through. It is not uncommon for more than 1,000 mm of precipitation to fall during the passage of a typhoon.

Megi is not disappointing in this regard. Over higher terrain, from 300 to 600 mm of rain may occur through Wednesday. On Tuesday rain has been falling at a rate of 25-50 mm per hour, with heavier precipitation recorded in some places. Many locations in the north of Taiwan may receive more than 300 mm within 24 hours, and 890 mm has already been recorded at Taipingshan, in the township of Datong.

The Japan Meteorological Agency (JMA) estimates the storm’s maximum wind speed near the center as 126 km/h at 12:45 UTC, on September 27, 2016, with wind gusts up to 180 km/h. Taiwan's Central Weather Bureau reports wind gusts up to 200 km/h at Wuqi, 159 km/hr at Taoyuan International Airport, 156 km/h at Pengjiayu, 134 km/hr at Songshan International Airport, and 117 km/h at Taichung.

Advance Preparation

Ahead of the storm authorities in many cities and counties closed schools and workplaces, and Taiwan's stock and foreign exchange markets closed on Tuesday. High speed rail services were suspended and the Taiwan Railways Administration halted all of its services except for commuter trains. More than 600 domestic and international flights were canceled and some highways were closed as a precaution.

Exposure at Risk

In Taiwan, given the strict building code and relatively good enforcement, structures are generally wind-resistant, and wind damage is usually concentrated on non-structural components or poorly built structures.

Low- to mid-rise buildings in Taiwan typically have reinforced concrete frames with brick infill walls. Some masonry residential buildings can also be found, although the majority of these were built prior to 1950. In recent years, these residences have given way to mid-rise apartment buildings and three-story residences, with both types generally of masonry construction. Most buildings in the country are fairly new, however, and recent residences tend to be high-rise complexes built in clusters, predominantly reinforced concrete and many with ceramic façades (although some are steel).

The commercial and industrial buildings in Taiwan usually date to 1970 or later and generally are built to better structural standards than residences. About half of Taiwan’s commercial and industrial stock is made of steel while the rest is mostly reinforced concrete.

Relief map of Taiwan showing the formidable central mountain range. (Source: Ksiom)

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Posting Date: September 27, 2016, 10:30:00 AM