Partners save 15% on every standard

Valid

GB/T 21075-2026Reservoir-induced earthquake hazard assessment (English PDF)

水库诱发地震危险性评价

Open the GB/T 21075-2026 preview as PDF

Preview — first pages of GB/T 21075-2026 (full document: 30 pages)

This is a limited preview

Buy now to download the full PDF (30 pages)

Issued by

SAMR; SAC

Level / Type

National · Recommended

Issue date

April 30, 2026

Implementation date

August 1, 2026

Scope

GB/T 21075-2026 is the English-translated version of 水库诱发地震危险性评价.

GB/T 21075-2026 is the Chinese national standard covering earthquakes triggered by filling a reservoir - the geological and seismological survey before a dam is built, the assessment of whether the impoundment could induce seismicity and of how large it could be. China has built more large dams than anyone, several in seismically active regions, which is why this assessment is a standard and not a research exercise. It replaces GB/T 21075-2007 and has been in force since 1 August 2026. It was issued on 30 April 2026 and has been in force since 1 August 2026, replacing GB/T 21075-2007. This page is published from the official record of the 2026 edition; the clause text of a standard this recent is not yet in circulation, and the figures, limits and tables it contains are those of the document itself, delivered in full with the English translation.

Document preview — GB/T 21075-2026

National Standard of the People's Republic of China

ICS: 91.120.25
Classification: P 15
Replacing: GB/T 21075-2007

Issued by: State Administration for Market Regulation; Standardization Administration of the PRC

4 General Requirements
4.1 Basic Provisions
4.3 Drawing Requirements
5 Geological survey of the reservoir area
7 Deterministic Evaluation
7.1 Division of Reservoir-Induced Earthquakes
8 Probability Evaluation
9 Overall Evaluation

Foreword

This document complies with the provisions of GB/T 1.1-2020 "Standardization Work Guidelines Part

1.Structure and Drafting Rules of Standardization Documents". Drafting. This document replaces GB/T 21075-2007 "Evaluation of Seismic Hazard Induced by Reservoirs". Compared with GB/T 21075-2007, except for the structure... Aside from adjustments and editorial changes, the main technical changes are as follows:

a) The definition of the reservoir-induced earthquake influence zone has been changed (see 3.4,.2007 version 3.4);

b) The definition of seismic induction factors has been added (see 3.5);

c) The scope and scope of application for reservoir-induced earthquake hazard assessment have been changed (see Chapter 4, Chapter 4 of the.2007 edition);

d) The regulations for map scales have been changed (see 4.3,

6.1 in the.2007 edition);

e) The regulations regarding the labeling content of reservoir-induced earthquake hazard assessment maps have been revised (see 4.3,

5.1 of the.2007 edition);

f) The requirements for collecting and organizing background data on seismic activity have been revised (see 6.1, 6.3, and

7.2 in the.2007 edition);

g) The requirements for library segmentation have been changed (see 7.1,

8.1 in the.2007 version);

h) The rules for collecting probability assessment data have been changed (see 8.1,

4.1 Basic Provisions

4.1.1 The induced seismic hazard assessment for newly built, renovated, and expanded reservoirs shall meet the following requirements.

a) When the reservoir capacity reaches or exceeds 5×10^8 m^3, or the dam height reaches or exceeds 100 m, the reservoir-induced earthquake hazard assessment should be conducted. evaluate;

b) When the reservoir capacity is between 1×10^8 m^3 and 5×10^8 m^3, the reservoir-induced earthquake hazard should be demonstrated and considered. evaluate;

c) When the reservoir capacity is less than 1×10^8 m^3, this document can be consulted to determine whether to conduct an evaluation after fully demonstrating its necessity.

4.1.2 For existing reservoirs, based on their reservoir capacity, dam height, and actual needs, it is advisable to conduct a feasibility study and determine the implementation of reservoir-induced earthquake hazard assessment in accordance with the provisions of 4.1.1. The necessity of sexual evaluation.

4.1.3 The spatial extent of the reservoir-induced earthquake influence zone should be defined based on the reservoir shoreline corresponding to the normal water level, extending towards the reservoir shoreline. The horizontal distance extends for no less than 15km.

4.2 Content Requirements The reservoir-induced earthquake hazard assessment should include the following tasks.

a) Geological survey of the reservoir area;

b) Investigation of seismic activity background and geostress field in the reservoir-induced earthquake-affected area;

c) Deterministic evaluation;

d) Probability evaluation;

e) Overall evaluation.

4.3 Drawing Requirements

4.3.1 The following maps should be submitted after the reservoir-induced seismic hazard assessment is completed.

a) Geological map;

b) Historical earthquake epicenter distribution map;

c) Reservoir-induced earthquake hazard assessment map.

4.3.2 The preparation of drawings shall comply with the following provisions.

a) Geological charts should be drawn according to the following content and requirements. 1) The distribution, attitude, nature, and latest activity patterns of major faults in the reservoir-induced earthquake-affected area; 2) The lithological assemblage or rock mass structure type, age, and boundaries of the strata that the reservoir water can come into contact with; 3) Location of the spring (cold spring and hot spring) outlet.

b) The geological map is primarily defined by the reservoir-induced earthquake influence zone; when active faults exist outside the influence zone, the reservoir-induced earthquake influence zone is considered. It extends beyond the scope of the affected area.

c) The earthquake epicenter distribution map indicates the start and end dates of the data and the earthquake magnitude.

d) The reservoir-induced earthquake hazard assessment map indicates the maximum magnitude and horizontal direction of the ground motion in each reservoir section within the reservoir-induced earthquake influence zone. Peak acceleration (hereinafter referred to as peak acceleration).

e) The map scale shall be no less than 1.250,000, and all maps shall indicate the location of the reservoir area and the dam site.

5 Geological survey of the reservoir area

5.1 The location, attitude, and dynamic characteristics of the main faults in the reservoir area should be verified, and relevant active fault data should be collected; and in this process... Based on this, the fault activity was identified in accordance with the provisions of GB/T 36072.

5.2 The occurrence, density, and properties of joints should be investigated and measured, and stereographic projections or rose diagrams of the joint measurements should be drawn.

5.3 The water content, permeability, and sealing conditions of various discontinuous surfaces should be collected and analyzed.

5.4 The lithology, occurrence, assemblage relationship and hydrogeological characteristics of the reservoir area should be reviewed.

5.5 The distribution of soluble rocks in the reservoir area, as well as the degree of karst development, scale, and connectivity with the reservoir water, should be investigated.

5.6 Data on large unstable geological bodies in the reservoir area should be collected and investigated.

5.7 Information on the location, flow rate, water temperature (hot springs), and other information of springs in the reservoir area, as well as their causes, should be collected and verified.

6.Investigation of seismic activity background and geostress field in the reservoir-induced earthquake-affected area

6.1 It is necessary to investigate and collect data on earthquakes with strong or greater impact in the reservoir area and their causes, and to compile isoseismal lines and instruments for earthquakes with a magnitude greater than or equal to M4.7. The peak ground acceleration of recorded earthquakes with strong perceptible force.

6.2 Seismic data for reservoir-induced earthquake-affected areas should be collected in accordance with the relevant provisions of GB 17741 regarding regional seismic activity assessment. Compile an earthquake catalog. When the collected earthquake data is insufficient, locally constructed and operated seismic networks or engineering-dedicated seismic monitoring networks can be utilized. Seismic data is used as a supplement.

6.3 The location of the epicenter of historical earthquakes in the reservoir-induced earthquake-affected area should be reviewed.

6.4 When a regional or local seismic network cannot control a reservoir-induced earthquake of magnitude

1.0 or greater within the affected area, procedures should be followed before impoundment. GB/T 31077 stipulates the construction of a reservoir seismic monitoring network to monitor the background seismic activity in the reservoir-induced earthquake-affected area. (Reservoir earthquakes) The monitoring network should ideally be completed and operational one year before water storage.

6.5 The following requirements shall be met when conducting a geostress field survey in the reservoir-induced earthquake-affected area.

7.1 Division of Reservoir-Induced Earthquakes

7.1.1 Reservoir-induced earthquakes are classified into the following three types.

a) A reservoir segment with a high probability of triggering earthquakes;

b) Less likely induced earthquake reservoir segments;

c) The reservoir section is not prone to inducing earthquakes.

7.1.2 The reservoir section for reservoir-induced earthquakes shall be delineated based on the following information, in accordance with the provisions of Appendix A.

a) Topographic and geomorphological features;

b) Lithological assemblage or rock mass structural characteristics;

c) The location of the seismogenic structure, the nature of the fault, its activity period, mode, degree of fracturing and cementation, and the morphology and scale of the folds;

d) Groundwater type, properties of aquifers and permeable discontinuous structural surfaces, and the relationship between recharge and drainage;

e) Distribution of soluble rocks, degree of karst development, and scale;

f) Infiltration conditions such as surface cover, underground permeable channels, and sealing conditions;

g) The geostress field and its relationship with major faults;

h) Background of seismic activity.

7.2 Determination of the maximum magnitude of reservoir-induced earthquakes The maximum magnitude of a reservoir-induced earthquake should be determined based on a comprehensive consideration of the following factors.

8 Probability Evaluation

8.1 Data on reservoir-induced earthquakes from both domestic and international sources should be collected, and a certain number of large-scale engineering projects where reservoir-induced earthquakes have not occurred should be randomly selected. For example, they together form the sample set. The proportion of reservoir-induced earthquake cases in the sample set to the total number of samples should not be less than 12%. The total number of samples should not be less than [a certain percentage]. There are 500.

8.2 Seismic induction factors should be selected from Appendix C to form a set of seismic induction factors. Among these, the basic seismic induction factors include reservoir capacity, reservoir depth, and lithological combination. Or rock mass structure type, tectonic stress environment or geostress state, fault activity. The set of seismic induction factors should contain at least 5 basic seismic inductions. factor.

8.3 Induced seismic factors are represented by their "states." Each induced seismic factor can be divided into several states, but should be divided into at least two states. Induced seismic factors The state division should comply with the provisions of Appendix C.

8.4 The predicted maximum magnitude of reservoir-induced earthquakes should be categorized (divided into several intervals), with at least two categorizations. Magnitude categorization It is advisable to take into account both the magnitude interval and the number of samples within the grade interval.

8.5 The induced earthquake factors and their states for different magnitude ranges of the sample should be statistically analyzed. The different states of each induced earthquake factor should be grouped together. The combination of inducing factors that constitute this magnitude earthquake is determined, and their probability of occurrence is statistically analyzed.

8.6 The induced earthquake factors and their states for each section of the reservoir being assessed should be analyzed. Each induced earthquake factor should be analyzed in detail. The state constitutes the combination of seismic induction factors for this reservoir section.

8.7 The probability of earthquake occurrence for different magnitudes in each reservoir section should be calculated according to formula (1).

9 Overall Evaluation

9.1 A comprehensive evaluation of the maximum magnitude of induced earthquakes in each section of the reservoir should be conducted. When the results of deterministic and probabilistic evaluations are inconsistent, the deterministic evaluation should prevail. The conclusions are primarily based on deterministic evaluations.

9.2 The maximum magnitude of the reservoir-induced earthquakes in each reservoir section should be comprehensively evaluated to assess the overall risk of reservoir-induced earthquakes.

9.3 The peak ground acceleration (PGA) of reservoir-induced earthquakes should be given. The relationship between PGA and magnitude should be determined according to Appendix D.

......
This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 30 pages — is available in the English PDF.

Editions of GB/T 21075

Edition	Title	Revision	Status
GB/T 21075-2026	Reservoir-induced earthquake hazard assessment	current edition	Current
GB/T 21075-2007	Reservoir-induced earthquake hazard assessment	previous edition	Superseded

This page sells the current edition, GB/T 21075-2026. Earlier editions are listed for reference only.

How to Buy GB/T 21075-2026

1Add to cart. Click the "Buy GB/T 21075-2026" button on this page. You can add more standards before checkout.
2Checkout. Enter your email and billing details. Payment is processed securely by Stripe (cards, Apple Pay, Google Pay supported).
3Instant delivery (0–9 sec). Delivery is automatic: within seconds of payment you'll receive an email with a secure download link. The link stays valid for 72 hours.
4Invoice included. A tax invoice is attached to the confirmation email. Need a custom invoice? Contact us.