## 1 Introduction  
During the 1950s, Dr. [PERSON] developed the so-called \"pali radiice\" or \"root piles\", a technical solution consisting of small diameter, vertical or inclined, micropiles (MPs) used to provide additional resistance to the existing foundation or/and soil. Technically speaking, MPs are small diameter piles, typically less than 300 mm, drilled and grouted nondisplacement piles, which are typically reinforced [1]. From the point of view of European execution standards, MPs are neither classified as displacement piles nor as bored piles, and a separate execution standard is provided: EN 14199:2015 [2].  
MPs are easy to install in areas with restrictions, such as limited access areas, limitations on vibration, and difficult soil conditions. This is due to the fact the MPs family includes many types and technologies, which give contractors the possibility to develop many \"problem-specific solutions\". Figures 1 and 2 present some applications of MPs [3].  
The use of MPs increased beyond the initial aimed scope; for example, they can also be used in slope stabilization (Figure 3). The use of MPs in the seismic engineering field was initially limited to retrofitting damaged structures and foundations, but after the 1995 Kobe earthquake in Japan, it was observed that MPs can also be beneficial for the superstructure during the seismic event, and it started to be conceived as a foundation system more than just a repair solution [1].  
Figure 1: MPs used for increasing foundation capacity of an existing building (after [3]).  
Figure 3: Reticulated network of MPs that form a composite base, used for soil stabilization (after [3]).  
Figure 2: MPs used for a new foundation (after [3]).  
inconvenience, such as the complexity and the requirements of periodical maintenance, which depend on the seismic dampers type [8].  
MPs can provide the same advantage of avoiding damages to the superstructure when being used in retrofitting, plus the relatively simple design and execution, while when considering the ability of enhancing the seismic behavior, seismic dampers are in the lead.  
After considering this, a question can arise regarding the possibility of a further study on MPs seismic behavior and their ability to affect the superstructure seismic behavior as well, in such a way that they keep their advantages, and they further enhance the seismic behavior of the superstructure. Additionally, using MPs alongside seismic dampers might provide another possible solution in enhancing the performance of the superstructure, increasing its resilience, while keeping all the advantages discussed previously. To answer this question, research is ongoing for increasing the understanding of the seismic behavior of MPs and MPed structures, the ability to affect and enhance the seismic behavior of the superstructure with using MPs, and by using MPs alongside seismic dampers.  
This paper at the beginning presents some very general and synthetic aspects about micropiles in order to set the scene for the further analyses. This paper further refers to the seismic behavior of MPs and MPed, including many actual references found in the literature, along with personal data syntheses and analyses of the results of other authors. No references are made to the static behavior of MPs, which is well known. Additionally, there are some personal contributions provided for using MPs in association with base isolator systems (BIS), which further need studies and research. The association MPs-BIS is briefly approached only from the MPs point of view, the BIS themselves beyond the scope of the paper.