diff --git a/inputs/gutenberg_richter.data b/inputs/gutenberg_richter.data
new file mode 100644
index 00000000..74909881
--- /dev/null
+++ b/inputs/gutenberg_richter.data
@@ -0,0 +1,53 @@
+ 0 1.4
+ 10 1.5
+ 20 1.7
+ 25 1.9
+ 30 2.1
+ 35 2.3
+ 40 2.4
+ 45 2.5
+ 50 2.6
+ 60 2.8
+ 70 2.8
+ 75 2.9
+ 85 2.9
+ 90 3.0
+100 3.0
+110 3.1
+120 3.1
+130 3.2
+140 3.2
+150 3.3
+160 3.3
+170 3.4
+180 3.4
+190 3.5
+200 3.5
+210 3.6
+230 3.7
+240 3.7
+250 3.8
+260 3.8
+270 3.9
+280 3.9
+290 4.0
+300 4.0
+310 4.1
+320 4.2
+330 4.2
+340 4.2
+350 4.3
+360 4.3
+370 4.3
+380 4.4
+390 4.4
+400 4.5
+430 4.6
+470 4.7
+510 4.8
+560 4.9
+600 5.1
+700 5.2
+800 5.4
+900 5.5
+1000 5.7
\ No newline at end of file
diff --git a/pylot/core/analysis/magnitude.py b/pylot/core/analysis/magnitude.py
index a772059f..3a430158 100644
--- a/pylot/core/analysis/magnitude.py
+++ b/pylot/core/analysis/magnitude.py
@@ -5,7 +5,7 @@ Created autumn/winter 2015.
 
 :author: Ludger Küperkoch / MAGS2 EP3 working group
 """
-
+import os
 import matplotlib.pyplot as plt
 import numpy as np
 from obspy.core import Stream, UTCDateTime
@@ -15,8 +15,14 @@ from scipy.optimize import curve_fit
 from scipy import integrate, signal
 from pylot.core.io.data import Data
 from pylot.core.util.dataprocessing import restitute_data, read_metadata
-from pylot.core.util.utils import common_range
+from pylot.core.util.utils import common_range, fit_curve
 
+def gutenberg_richter_relation(delta):
+    relation = np.loadtxt(os.path.join(os.path.expanduser('~'),
+                            '.pylot', 'gutenberg_richter.data'))
+    # prepare spline interpolation to calculate return value
+    func, params = fit_curve(relation[:,0], relation[:, 1])
+    return func(delta, params)
 
 class Magnitude(object):
     '''