DB/T 81-2020 in English
VALIDActive fault survey-Paleoseismic trenching
- Issued on:2020-03-30
- Implemented on:2020-07-01
- File Format:PDF
- Delivery:Via email within 5 business days
$553.00
| Standard No: | DB/T 81-2020 |
| Document status: | VALID |
| Title in English: | Active fault survey-Paleoseismic trenching |
| Title in Chinese: | 活动断层探察 古地震槽探 |
| Language: | English |
| File Format: | Electronic (PDF) |
| Delivery: | Via email within 5 business days |
| Issued on: | 2020-03-30 |
| Implemented on: | 2020-07-01 |
| ICS Classification: | 91.120.25-Seismic and vibration protection |
| Chinese Classification: | P15-Engineering seismic resistance |
| Professional Classification: | DB-Provincial Standard |
| Related Keywords: | strike-slip fault reverse fault normal fault trench depth ≥2.5m ≥2 times
active fault active fault exploration series active fault exploration work strike-slip fault |
| Related Topics: | fault
Paleo+ detecting animals animal detection Acid exploration Explore active layer Late Quaternary detecting animals normal fault broken antiquity animal detection Active fault detection db-T15 db4403/t 81-2020 Slot wave seismic exploration |
本标准规定了古地震槽探的前期准备、地点选择、现场开挖、样品采集、古地震事件识别以及相关成 果数据入库的要求。
本标准适用于活动断层地质填图、城市活动断层探测以及活动断层鉴定中的古地震槽探工作。地震科学考察也可参照使用。
Introduction
Standard Background and Technology Evolution
As an important part of the Active Fault Exploration series of standards, this standard regulates the paleoseismic trench exploration technology. my country started the active fault exploration work during the "Eighth Five-Year Plan" period, and gradually formed a complete technical system through the experience accumulation of major disasters such as the Wenchuan earthquake. Together with DB/T 69-2017 Remote Sensing Survey and DB/T 71-2018 Fault Geomorphology Measurement, it forms a multi-dimensional exploration framework.
Comparison of core technical requirements
| Technical elements | Strike-slip fault | Reverse fault | Normal fault |
|---|---|---|---|
| Trench depth | ≥2.5m | ≥2 times of co-seismic displacement | ≥2 times of co-seismic displacement |
| Sampling strategy | Sampling of upper and lower boundaries of event layer | Growth stratum + deformation layer | Colluvial wedge + deformation layer |
| Identification mark | Duanshitang accumulation sequence | Sudden change in thickness of growth strata | Unconformity in angle of colluvial wedge |
Key points for implementation of key technologies
1. Principles for trench site selection
Give priority to tectonic geomorphic units such as fault troughs and fault ponds, which must meet the following requirements:
- Strike-slip fault: width of pull-apart basin <100m, diameter of fault pond <100m
- Reverse fault: continuous accumulation thickness >2 times of co-seismic displacement
- Avoid areas with strong transformation such as debris flow and landslide
2. Paleoseismic dating technology
Multi-trench cross-validation is carried out using the successive limitation method (Appendix D):
- Carbon-14 dating gives priority to the collection of short-lived samples such as seeds and bark
- Luminescence dating is suitable for volcanic ash, baked layers, etc.
- The youngest age value is taken from the same stratigraphic unit
Typical application cases
The Anning River Fault Zone revealed a 3400-year earthquake recurrence history through the combined trenching technology (Wang et al., 2014):
- Five paleo-earthquake events were identified, with a recurrence interval of 300-700 years
- The identification results were verified by the displacement limit method (B=16.36%)
- A fault displacement-age relationship model was established
Implementation suggestions
It is recommended to combine GIS technology to establish a three-dimensional trenching model:
- Orthophotography is used to produce orthophotos (1:50 scale)
- Key information such as fault traces and sampling points are marked
- Compatible with DB/T 65-2016 database specification
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