在AWS Aurora中，当某个可用区（AZ）出现故障时，读取副本将自动切换到其他可用区的读取副本。此外，您可以通过创建多个读取副本来增加可用性，并在多个可用区中分配它们，以确保高可用性。

以下是一个示例代码，用于创建AWS Aurora使用两个AZ的读取副本：

{
 "Type" : "AWS::RDS::DBInstance",
 "Properties" : {
 "DBInstanceIdentifier" : "DBInstance1",
 "DBInstanceClass" : "db.t2.micro",
 "Engine" : "aurora",
 "AvailabilityZone" : "us-west-2a",
 "DBSubnetGroupName" : { "Ref" : "SubnetGroup" },
 "PreferredMaintenanceWindow" : "Mon:03:00-Mon:04:00",
 "ReadReplicaSourceDBInstanceIdentifier" : "DBInstance1",
 "Tags" : [ {"Key" : "Name", "Value" : "DBInstance1"},
 {"Key" : "Environment", "Value" : "Production"} ]
 }
},
{
 "Type" : "AWS::RDS::DBInstance",
 "Properties" : {
 "DBInstanceIdentifier" : "DBInstance2",
 "DBInstanceClass" : "db.t2.micro",
 "Engine" : "aurora",
 "AvailabilityZone" : "us-west-2b",
 "DBSubnetGroupName" : { "Ref" : "SubnetGroup" },
 "PreferredMaintenanceWindow" : "Mon:03:00-Mon:04:00",
 "ReadReplicaSourceDBInstanceIdentifier" : "DBInstance2",
 "Tags" : [ {"Key" : "Name", "Value" : "DBInstance2"},
 {"Key" : "Environment", "Value" : "Production"} ]
 }
}

这将创建两个AWS Aurora读取副本，分别位于两个不同的可用区（us-west-2a和us-west-2b）。如果出现任何可用区故障，您的应用程序将自动切换到另一个可用区的读取副本。