Fixed eventlist not working after locating twice

Changed exception when less then 2 horizontals are found to warning

pylot/core/analysis/magnitude.py

@@ -221,11 +221,16 @@ class LocalMagnitude(Magnitude):
 
         power = [np.power(tr.data, 2) for tr in st if tr.stats.channel[-1] not
                  in 'Z3']
-        if len(power) != 2:
-            raise ValueError('Wood-Anderson amplitude defintion only valid for '
-                             'two horizontals: {0} given'.format(len(power)))
-        power_sum = power[0] + power[1]
-        #
+	# checking horizontal count and calculating power_sum accordingly
+	if len(power) == 1:
+		print ('WARNING: Only one horizontal found for station {0}.'.format(st[0].stats.station))
+		power_sum = power[0]
+	elif len(power) == 2:
+		power_sum = power[0] + power[1]
+	else: 
+		raise ValueError('Wood-Anderson aomplitude defintion only valid for'
+			' up to two horizontals: {0} given'.format(len(power)))
+ 
         sqH = np.sqrt(power_sum)
 
         # get time array