“Is this on a fault line?” is a question every buyer in Taichung has asked since the 921 earthquake. The short answer: proximity to a fault is a location risk, and whether the building can withstand an earthquake is a structural question. Check them separately. Location can be checked in three free official systems run by the Ministry of Economic Affairs. Whether to buy depends on whether the site falls inside a legally declared geologically sensitive area or a building-restriction zone, and on the project’s own seismic design, not on how many kilometres it is from a red line on a map.
Three numbers to remember: 36 active faults in Taiwan on the Ministry’s 2021 map; 27 declared active-fault geologically sensitive areas as of end-2025; and a zone width of about 150 metres on each side of the fault. Based on the Geological Survey and Mining Management Agency’s Taiwan active fault site (data updated 2026-09-20).
Active fault versus sensitive area
An active fault is a geological line. A geologically sensitive area (地質敏感區) is a legal band drawn along that line. When you check a location, the band is what matters.
The Ministry defines an active fault as one that has moved in roughly the last 100,000 years and is likely to move again. The 2021 map lists 36. From October 2025 they are no longer split into class 1 and class 2; all are simply called active faults. An active-fault geologically sensitive area is the statutory zone declared under Article 5 of the Geology Act, in principle about 150 m on each side of the fault. Where deformation is asymmetric, the main side is about 200 m and the other about 100 m. As of end-2025, 27 have been declared.
The authority itself warns that outside a sensitive area does not mean safe, and inside one does not mean you cannot build or live there; it means an extra geological investigation before development.
The three official systems
You only need three systems from the Geological Survey and Mining Management Agency: the active fault map, the geologically sensitive area query, and the soil liquefaction potential query. All are free and work from an address.
| What to check | System | How |
|---|---|---|
| Nearby active faults and their direction | Taiwan active fault site and GIS query | View the map and strip geological map, zoom to street block level |
| Whether the site is inside a sensitive area | Geologically sensitive area query | Enter the lot number or address; the result can be printed. This is the one with legal significance |
| Soil liquefaction potential (high, medium, low) | Soil liquefaction potential query (Taichung version) | View primary or intermediate data; the coastal districts of Qingshui, Wuqi, Longjing and Shalu have intermediate-level maps |
Use the official sites (updated 2026-09-20).
Our view: The fault map is research output, the sensitive area is a legal boundary, and the liquefaction map comes in primary and intermediate grades. They differ in precision. Screenshot and save the results, then take them to the developer or agent. The conversation then moves past “I heard there is a fault over there”.
Active faults around Taichung
The Ministry’s map shows seven faults in and around Taichung: Sanyi, Tachia, Tiechanshan, Tuntzuchiao, Changhua, Chelungpu and Tamaopu-Shuangtung. Of these, Chelungpu, Sanyi, Tachia, Tuntzuchiao and Tamaopu-Shuangtung have declared sensitive areas; Tiechanshan and Changhua had not been declared as of end-2025.
The Chelungpu fault was the main fault of the 921 earthquake. As described by the Taiwan Earthquake Model, it runs from Zhuolan in Miaoli in the north, south through Dongshi, Fengyuan, Tanzi, Beitun, Taiping, the eastern edge of Dali and Wufeng, into Nantou, about 91.9 km in total, roughly along the boundary between the hills and the plain. Sanyi, Tuntzuchiao, Tachia and Tiechanshan lie north of Taichung and along the coast, Changhua to the south-west, and Tamaopu-Shuangtung in the eastern hills. These are only descriptions of direction; whether a given community is inside a sensitive area is decided solely by the sensitive area query. See our area pages for the Taichung redevelopment zones.
What the rules require
Being inside a sensitive area is not a building ban. Under Article 8 of the Geology Act, a site geological investigation and geological safety assessment, certified by a licensed engineer, must be included with the development application. Actual building bans and limits come from three separate legal sources with different scopes.
| Where it applies | Legal basis | Rule |
|---|---|---|
| Geologically sensitive areas (nationwide) | Geology Act Articles 8, 10 and 11 | Site geological investigation and safety assessment before development, engineer-certified and submitted; not a ban |
| Hillside land | Building Technical Regulations, Design and Construction chapter, Article 262 | By largest historical earthquake: M≥7, no building within 100 m each side of the fault; M6 to 7, 50 m; below M6 or no record, 30 m |
| Non-urban land | Building Management Regulations for Regional Plan Areas, Article 4-1 | County or city may declare zones: no public buildings; private homes and farmhouses limited to two storeys with eave height of 7 m |
| Chelungpu fault, urban planning areas (post-921) | City and county announcements under the Urban Planning Act | 15 m each side of the surface trace: public land no building, private land limited to two storeys under 7 m, deed annotated “located on fault” |
Based on the national law database and Legislative Yuan research (updated 2026-09-20); local rules take precedence where they exist. For a resale home, an annotation “located on fault” (位於斷層上) on the transcript or deed is the most direct signal. When buying through an agent, ask for the query results to be attached to the disclosure statement and read them before signing an offer or paying earnest money.
Proximity and seismic resistance are two different things
Distance to a fault determines how hard the ground shakes; the building’s seismic resistance determines whether the structure holds up. The first is a location check, the second a design and construction check.
The code already accounts for location. Since the 2005 (ROC year 94) revision of the seismic design code, buildings near faults must use an increased design earthquake force, and the version effective October 2022 adjusted the near-fault coefficients according to the 2012 fault map. In other words, a new project near a fault, designed to the current code, already carries a higher design force than one further away.
- Location: sensitive area result, liquefaction potential, deed annotation.
- Structure: the code version matching the building permit date, the structural type (RC, SRC or SC), seismic labels and damping or base isolation. See our guides on seismic ratings and RC, SRC and SC structures.
- Age: for resale homes see the viewing checklist.
What to check and ask before buying
The order is: check the three systems, ask the developer or owner for documents, then decide whether to negotiate.
- Check: screenshot all three results.
- Ask the developer: is there a site borehole report and geological safety assessment? Did the structural design consider near-fault effects? Can we see the external structural review or seismic label documents?
- Ask the owner or agent: any annotation on the deed or transcript? Any damage and repair records from 921? What does the site-use control field of the disclosure statement say?
- Ask the bank: no law prevents lending inside a sensitive area, but valuation is case by case. Get a pre-approval before signing. See our guides on the down payment, the buying process and resale, presale and new build.
Our view: Asking a developer “is it on a fault?” usually gets a one-word “no”. Ask instead “can I see the geologically sensitive area query result for the site?”. They have to produce a document, and the answer then carries weight.
FAQ
Can I buy a home near a fault?
It depends on whether it is inside a declared sensitive area or a building-restriction zone, and on the project’s seismic design, not on distance in kilometres. Confirm with the sensitive area query first, then check the permit date and structural documents.
Can I get a mortgage inside a sensitive area?
The law does not prohibit it, but banks value case by case. The Geology Act only requires an investigation and assessment before development. Ask the bank for pre-approval on loan-to-value and rate before signing.
How do I know if a home is in a sensitive area?
Enter the address or lot number in the Geological Survey and Mining Management Agency’s sensitive area query. For a resale home, also look for a “located on fault” annotation on the deed or transcript.
Can I buy in a high liquefaction potential zone?
Yes. The key is the foundation type and whether ground improvement was done. Liquefaction affects the foundation, not the structure itself. Ask the developer for the borehole report and foundation design; for older homes look for signs of settlement or tilt.
Conclusion
A fault is not a reason to walk away; not checking is. The three official systems take ten minutes, and the rest comes down to structural documents and a bank pre-approval. If you cannot read the results, contact us.