diff --git a/src/qseek/models/detection.py b/src/qseek/models/detection.py
index 4a9d89c9..a33d7df3 100644
--- a/src/qseek/models/detection.py
+++ b/src/qseek/models/detection.py
@@ -241,6 +241,8 @@ def get_waveforms(
             )
         )
         accessor_id = "qseek.event_detection"
+        if not times:
+            return []
 
         tmin = min(times).timestamp() - seconds_before
         tmax = max(times).timestamp() + seconds_after
diff --git a/src/qseek/models/semblance.py b/src/qseek/models/semblance.py
index 16ed130f..53e03ff7 100644
--- a/src/qseek/models/semblance.py
+++ b/src/qseek/models/semblance.py
@@ -139,11 +139,11 @@ def __init__(
                 fill_zero_bytes(self.semblance_unpadded)
         else:
             logger.info(
-                "re-allocating semblance memory: %d", human_readable_bytes(n_values * 4)
+                "re-allocating semblance memory: %s", human_readable_bytes(n_values * 4)
             )
             self.semblance_unpadded = np.zeros((n_nodes, n_samples), dtype=np.float32)
 
-            Semblance._semblance_allocation = self.semblance_unpadded
+            Semblance._semblance_allocation = self.semblance_unpadded.ravel()
             Semblance._stats.semblance_allocation_bytes = self.semblance_unpadded.nbytes
 
         self._stats.semblance_size_bytes = self.semblance_unpadded.nbytes