# Urban Seismic Networks: A Worldwide Review
## 2 USN Catalogue
### Objectives
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**ID** & **Nodes** & **Area km\({}^{2}\)** & **Density log (nodes/km\({}^{2}\))** & **Start Year** & **Duration Years** & **Sensor Type** & **Transmission** \\ \hline
77 & 27 & \(1200\) & \(-1.68\) & \(2016\) & \(0.3\) & Velocimeter & No transmission \\
78 & 9 & \(1.5\) & \(0.78\) & \(2016\) & \(2\) & Low cost MEMS & Real-time \\
79 & 220 & 1 & \(2.34\) & \(2017\) & \(6\) & Low cost MEMS & Real-time \\
80 & 11 & 35 & \(-0.50\) & \(2017\) & \(6\) & MEMS Accelerometer & Real-time \\
81 & 8 & 0.15 & \(1.73\) & \(2017\) & \(2\) & Foreo Balance Accelerometer & No info \\
82 & 140 & 3450 & \(-1.39\) & \(2017\) & \(6\) & Velocimeter & Real-time \\
83 & 12 & 320 & \(-1.43\) & \(2017\) & \(0.08\) & Velocimeter & No info \\
84 & 11 & 15 & \(-0.13\) & \(2017\) & \(5.8\) & Low cost MEMS & Real-time \\
85 & 13 & 0.8 & \(1.21\) & \(2017\) & \(2\) & Low cost MEMS & Real-time \\
86 & 300 & 12000 & \(-1.60\) & \(2017\) & \(5.7\) & Force Balance Accelerometer & Real-time \\
87 & 8 & 1.5 & \(0.73\) & \(2017\) & \(0.5\) & Force Balance Accelerometer & No info \\
88 & 13 & 45 & \(-0.54\) & \(2017\) & \(1.4\) & Velocimeter & No info \\
89 & 200 & 3600 & \(-1.26\) & \(2017\) & \(3.3\) & Velocimeter & Real-time \\
90 & 7 & 2 & \(0.54\) & \(2018\) & \(2\) & Low cost MEMS & Near real-time \\
91 & 20 & 5 & \(0.60\) & \(2018\) & \(3\) & MEMS Accelerometer & Real-time \\
92 & 12 & 3 & \(0.60\) & \(2018\) & \(5\) & Low cost MEMS & Near real-time \\
93 & 5 & 1 & \(0.70\) & \(2018\) & \(5\) & Low cost MEMS & Near real-time \\
94 & 32 & 3 & \(1.03\) & \(2018\) & \(0.09\) & Velocimeter & No info \\
95 & 112 & 200 & \(-0.25\) & \(2018\) & \(0.3\) & Velocimeter & No transmission \\
96 & 88 & 1000 & \(-1.06\) & \(2019\) & \(0.08\) & Velocimeter & No transmission \\
97 & 6 & 325 & \(-1.73\) & \(2019\) & \(0.08\) & Velocimeter & No info \\
98 & 19 & 10 & \(0.28\) & \(2019\) & \(1\) & Velocimeter and accelerometer & Near real-time \\
99 & 9 & 17 & \(-0.28\) & \(2019\) & \(0.67\) & Velocimeter & No transmission \\
100 & 113 & 450 & \(-0.60\) & \(2019\) & \(0.7\) & Velocimeter & No transmission \\
101 & 15 & 25 & \(-0.22\) & \(2020\) & \(2.5\) & Low cost MEMS & Real-time \\
102 & 6 & 21 & \(-0.54\) & \(2020\) & \(2.13\) & Velocimeter and accelerometer & Real-time \\
103 & 14 & 10 & \(0.15\) & \(2021\) & \(2\) & Low cost MEMS & Near real-time \\
104 & NA & 450 & \(2021\) & \(2\) & Low cost MEMS & Real-time \\
105 & 32 & 150 & \(-0.67\) & NA & NA & Low cost MEMS & Real-time \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._* _Seismic intensity mapping_. Under this definition, we have grouped the networks which provide measurements of the ground motion intensity at the nodes of the urban network after an earthquake. These measurements can be straightforwardly used to map the distribution of the peak ground shaking for a given event as well as to produce products known as _shakemaps_. These depict the spatial distribution of peak ground motion, usually taking into account the recorded peak ground acceleration (PGA) or peak-ground velocity (PGV) together with information about the event source (e.g., magnitude, location) and the local site amplification and attenuation laws [152; 153]. The distribution of ground motion shaking intensity is a very useful parameter for evaluating the potential damage. While this objective may partially overlap with the previously listed objectives, it is distinguished by its timing, as the action need not necessarily take place immediately after the earthquake. * _Site effect research._ Among the factors that control the expected ground motion (i.e., the seismic hazard), site effects play a major role. Site effects can be generally defined as alterations to the earthquake's characteristics in terms of amplitude, frequency, and duration of the wave field due to specific stratigraphic or topographic conditions [154]. Such effects can be significant, and can be evaluated with a variety of sensors and methods [155; 156; 157; 158].