Seismicity

Seismicity on a global scale

The seismicity is all the earthquakes -Erscheinungen an area. Spatial and temporal distribution as well as energy and sequence of the occurring earthquakes can be examined and evaluated seismologically , so that an assessment of the seismicity is possible for most places on earth. In a worldwide comparison it is greatest at the plate boundaries of the continental plates .

Seismological basics

The recording of earthquakes with seismographs allows the calculation of the location and time as well as the released energy ( magnitude ) by evaluating seismograms . The sensitive measuring devices register events, the energy release of which differs by many powers of ten . Can be recorded so catastrophic , seldom takes place as well as the frequent, but without instrument is not perceptible earthquakes micro-earthquakes . With regard to an area, it is possible to compile these properties of the occurring earthquakes in a list, to evaluate them in diagrams or to represent them on a map.

Calculation of seismicity

In addition to the rather qualitative representation of the seismicity described above, a quantitative calculation is common. This assumes equally large areas of the area under consideration (defined by a coordinate interval of geographical latitude and longitude ) and, due to the shell structure of the earth, differentiates between different depth ranges (up to 50 km, 50 - 300 km and more than 300 km depth). With these specifications, the seismicity S results as follows:

${\displaystyle S={\frac {\sum _{i}{E_{s0}}_{i}}{{\delta \phi }_{0}{\delta \lambda }_{0}{\delta h}_{0}{\delta t}_{0}}},}$

in which

${\displaystyle {E_{s0}}_{i}}$: Energy of a single event

${\displaystyle {\delta \phi }_{0}}$: Latitude interval

${\displaystyle {\delta \lambda }_{0}}$: Longitude interval

${\displaystyle {\delta h}_{0}}$: Range of depth of focus

${\displaystyle {\delta t}_{0}}$: Interval of the cooking time

The unit of measurement of the seismicity calculated in this way is 10 ^x erg / km ³ * a , where x is an exponent between 10 and 30.

See also

• Richter scale
• Coda (seismology)
• Swarm of earthquakes

literature

• Götz Schneider: Earthquake. An introduction for geoscientists and civil engineers . 2004, ISBN 978-3-8274-1525-7 , pp. 12 ff .