Logz.io creates a log entry every time an alert is triggered, even if no notification is sent out. So if an alert is triggered while notifications are suppressed, or if you configured a non-critical alert without notifications, the alert is still logged.
To view triggered alerts, select Alerts > Triggered alerts from the top menu.
View a triggered alert in Kibana
To see a triggered alert in Kibana, hover over the alert, and then click View in Kibana.
This takes you to the alert query for the time period that triggered the alert. Using Kibana, you can explore your logs and get a better idea of the conditions that led to the triggered alert.