Typhoon Halong

Pre-Landfall 2 | Summary
Posting Date: August 8, 2014, 11:30:00 AM

Typhoon Halong passed 40 km east of Japan’s Daito Islands (located about 320 km east of Okinawa) Thursday local time, bringing with it maximum sustained winds of 115 km/h and heavy rain. The small island of Minamidaitōjima was especially hard hit as over 100 mm of rain were recorded in just 24 hours. Overall, the Daito islands fared well, however, with no significant damage reported.

The mainland of Japan has already begun to experience Halong’s effects, as Kyushu and Shikoku received more than 50 mm of rain, with 50-100 mm of rain occurring in just a 6-hour time period near Kochi. Conditions will continue to deteriorate across Kyushu, Shikoku, and western Honshu through Saturday evening as the rain and winds pick up in intensity.

Wind gusts between 95 km/h and 130 km/h are expected to be widespread in the vicinity of the storm’s landfall location with destructive wind gusts between 130 km/h and 160 km/h possible on the southern coasts of Shikoku and western Honshu (in the vicinity of Fukuyama and Okayama). Rainfall totals in locations across Shikoku could top 500 mm. Such torrential rain heightens the risk of severe flooding and landslides with recent heavy rain from tropical storm Nakri exacerbating the danger. Residents are being warned to stay on high alert for the threat of landslides and to evacuate as early as possible when advised to do so by local officials.

Conditions farther away in Tokyo will be quite a bit milder, with only 25-50 mm of rain expected and wind gusts of 80 km/h.

 Track map for Typhoon Halong (Source: JMA)

Exposure at Risk

The majority of the residential buildings in Kyushu and Shikoku consist mostly of wood-frame construction. At the expected wind speed levels, these structures may experience moderate to high cladding and roofing damage. For engineered buildings, such as reinforced concrete and steel buildings, expected structural damage is very low to none. Commercial building cladding and roof coverings could experience moderate levels of damage.

The vulnerability of buildings to flood damage varies by construction type. For a given flood depth, a residential wood-frame building is expected to sustain more damage than a residential masonry building. Concrete construction is less vulnerable to flood than steel or masonry. Commercial and apartment buildings usually have stronger foundations than residential buildings, and are thus better able to resist flood loads.

Water damage to machinery and contents drives most flood loss. Because damage is usually limited to the lower stories of a building, high-rise buildings will experience a lower damage ratio—the repair cost compared to the total replacement value of the building—than low-rise buildings because a smaller proportion of the building is affected.

Flood insurance does not exist as a standalone policy in Japan. Instead, property owners can opt to purchase flood coverage as part of a standard fire insurance policy. In typical Japanese flood policy coverage, a specified payout is made only when actual damage falls within a specified range of loss.

The AIR tropical cyclone team will continue to monitor Typhoon Halong and will provide updates as necessary.

Pre-Landfall 2 | Downloads
Posting Date: August 8, 2014, 11:30:00 AM