def update_param(event, param):
    """ update the param based on event information """
    origin = event.preferred_origin()
    origin = event.preferred_origin()
    event_latitude = origin.latitude
    event_longitude = origin.longitude
    event_time = origin.time
    param['starttime'] = event_time + param['relative_starttime']
    param.pop('relative_starttime')
    param['endtime'] = event_time + param['relative_endtime']
    param.pop('relative_endtime')
    param['event_latitude'] = event_latitude
    param['event_longitude'] = event_longitude
