AWS SHIELD STANDARD LOGGING

I don't believe there is any detailed logging for AWS Shield Standard, not even in Amazon CloudWatch.
https://docs.aws.amazon.com/waf/latest/developerguide/monitoring-cloudwatch.html which states for AWS Shield advanced. Also, the events page in the console is for AWS Shield Advanced.

You can see total account activity detected in the Getting Started page - https://docs.aws.amazon.com/waf/latest/developerguide/ddos-standard-event-visibility.html

AWS Shield is going to mitigate any Layer 3/4 DDoS attack automatically so it isn't a concern for your environment. AWS Shield Advanced is used to protect your Amazon CloudFront, Load Balancer traffic, etc from being DDoS'ed.