diff --git a/Assets/Cryville.EEW.Unity/UI/EventOngoingListView.cs b/Assets/Cryville.EEW.Unity/UI/EventOngoingListView.cs
index 6cfcc98..e3f0fec 100644
--- a/Assets/Cryville.EEW.Unity/UI/EventOngoingListView.cs
+++ b/Assets/Cryville.EEW.Unity/UI/EventOngoingListView.cs
@@ -79,7 +79,7 @@ namespace Cryville.EEW.Unity.UI {
 			m_currentView.SetViewModel(e, true);
 			var keyProp = e.Properties.FirstOrDefault();
 			_displayingViews[_index].SetCurrent(true);
-			_tickDown = Math.Max(0, keyProp?.Severity ?? 0) * 4 + 4;
+			_tickDown = MathF.Exp(Math.Max(-1f, keyProp?.Severity ?? -1f) + 1);
 			m_currentView.gameObject.SetActive(true);
 			Worker.Instance.SetCurrent(e);
 		}