I. INTRODUCTION  
A. Contributions of This Article  
B. Comparison with Related Surveys  

II. BACKGROUND  
A. What is Blockchain?  
B. Layered Architecture of Blockchain  
C. What is Anomaly Detection?  
D. Anomaly Problem in Blockchain Layers  
E. Technical Challenges while Integration of Anomaly Detection in Blockchain  

III. FUNDAMENTAL GUIDELINES TO IDENTIFY ANOMALOUS BEHAVIOR IN BLOCKCHAIN  
A. Types of Anomalous Attacks on Blockchain  
B. Categorization and Functioning of Anomaly Detection Models for Blockchain Technology  
C. Evaluation Metrics being used to Identify Anomalies  
D. Key Requirements for Anomaly Detection Mechanisms Design  

IV. ANOMALY DETECTION IN DATA LAYER OF BLOCKCHAIN  
A. Bitcoin Fraud Detection  
B. Generic Framework Design for Blockchain Anomaly  
C. Behavior Pattern Classification  
E. Tx Relative Similarity Clustering  
F. Summary and Insights  

V. ANOMALY DETECTION IN NETWORK LAYER OF BLOCKCHAIN  
A. Malicious Accounts on Network  
B. Malicious Forks in Network  
C. Anomalous Tx on Network  
D. Network Entropy Detection  
E. Summary and Insights  

VI. ANOMALY DETECTION IN INCENTIVE LAYER OF BLOCKCHAIN  
A. Bitcoin Fraud Detection  
B. Malicious Blockchain Accounts  
C. Incentive Attack Classification  
D. Market Volatility Prediction  
E. Summary and Insights  

VII. ANOMALY DETECTION IN CONTRACT LAYER OF BLOCKCHAIN  
A. Paxos Anomaly in Blockchain  
B. Faulty Signals & Tx Detection  
C. Anomaly in Contracts Bytecode  
D. Detecting Ponzi Contracts  
E. Malicious Threats in Smart Contracts  
F. Tagging & Log based Anomaly Prevention  
G. Summary and Insights  

IX. CONCLUSION