Anomaly detection plays a crucial role in process mining, an approach that identifies and analyzes business processes by extracting information from logs, tracing, or historical data. This helps organizations improve their efficiency, effectiveness, and cost-effectiveness by identifying potential problems or bottlenecks early on.

In the context of IT networks, anomaly detection is essential for enhancing operational security because it can help detect unusual behavior patterns that might indicate a cyberattack, such as unauthorized access attempts, denial-of-service attacks, or malware infections. 

The impact of anomaly detection in process mining and IT networks includes:

1. Early Detection: Anomalies detected by anomaly detection systems can be used to identify potential risks before they escalate into more significant problems.

2. Improved Security: By identifying unusual behavior patterns, anomaly detection helps prevent cyber-attacks before they occur, reducing the risk of data breaches or loss of sensitive information.

3. Efficient Operations: With better control over network operations and security, IT teams can respond faster to any anomalies detected in real-time, ensuring that operations remain operational with minimum disruption.

4. Cost Reduction: By identifying potential security vulnerabilities early on, organizations can take proactive measures to mitigate risks before they become costly issues, leading to cost savings.

5. Improved Compliance: Anomaly detection tools provide a basis for compliance checks, which are essential for organizations seeking to ensure adherence to regulatory standards and requirements related to data protection and cybersecurity.

In summary, anomaly detection in process mining is pivotal for IT networks' operational security because it helps detect potential threats early on and ensures that the organization has an efficient response mechanism. By implementing such systems effectively, businesses can maintain their operational efficiency while enhancing security posture through proactive measures.