Cell Broadcast Issuance and Response Operations
High-Risk Secondary Disaster Zone Alert Process
- FEMA System Automated Alert： When rainfall reaches the Attention Value, an automated pre-alert cell broadcast is issued to local residents, and an R10 form is faxed to inform local governments and relevant units such as rail and highway authorities.
- Local Government Preventive Measures： For post-disaster sediment-sensitive areas (Type C), preventive evacuation is initiated when a Debris Flow Yellow Alert is issued in the vicinity.
Rainfall Duration and Attention Value Table
| Category | Rainfall Duration | 1 Hour (mm) |
3 Hours (mm) |
12 Hours (mm) |
|---|---|---|---|---|
| Category 1 | Rainfall Attention Value | 15 | 30 | 80 |
| Category 2 | Rainfall Attention Value | 20 | 50 | 170 |
| Category 3 | Rainfall Attention Value | 25 | 80 | 200 |
| Other | Attention Value set according to local conditions | - | - | - |
Explanation of Rainfall Attention Value Categories
| Category | Definition and Explanation |
|---|---|
| Category 1 | Areas where collapse variation was triggered by an earthquake event, and which have not yet experienced a rainfall event. |
| Category 2 | Areas where collapse variation was triggered by heavy rain, and which have not yet experienced a rainfall event. |
| Category 3 | Areas where collapse variation or disaster was triggered by an earthquake, typhoon, or heavy rain, and which have experienced at least 2 rainfall events exceeding the Attention Value, or where sediment control measures have been implemented. |
| Other | Areas prone to disaster requiring attention or areas of localized creep in large-scale landslides. |
Cell Broadcast Cases
2025/5/18 TRA Heren and Chongde Section: Debris Flow Covered Tracks, Tze-Chiang Limited Express No. 477 Emergency Stop
- 15:30 As hourly rainfall exceeded the Attention Value, a pre-alert cell broadcast was sent.
- 16:10 Heren = Chongde During heavy rainfall between Heren and Chongde, the river became torrential, and debris flow covered the tracks. No. 477 train made an emergency stop. Fortunately, no casualties were reported.
2025/5/18 Evening Yilan County DF151 Experienced Debris Flow Disaster, Residential Buildings Damaged
- 17:00 As hourly rainfall reached the Attention Value, a pre-alert cell broadcast was sent.
- In the evening, Yilan County, Toucheng Township, Shicheng Village (opposite Shicheng Train Station), Yilan DF151 experienced a debris flow disaster. Sediment overflowed the downstream sedimentation basin and rushed into residential buildings, causing 5 protected households to be affected. Fortunately, no casualties were reported.
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