Seismic and Tsunami Risk Analysis for Installing Resilient Power Systems Based on Isolated Microgrids on Buildings: The Case of Puerto Ayora in Santa Cruz Island, Galapagos

Abstract

Due to their geographical condition and worldwide environmental protection policies, the Galapagos Islands must opt for implementing clean energy infrastructure considering natural hazard effects that can directly affect the resilience of community residents. Santa Cruz Island is part of this archipelago, with rich biodiversity in flora and unique fauna. This study proposes identifying earthquake and tsunami risk assessment components on the island, such as the infrastructure vulnerability of Puerto Ayora, the central city of Santa Cruz Island. The FEMA P-154 and FEMA P-646 methodologies are used to classify buildings for technically installing microgrids based on photovoltaic generation systems. For this purpose, maps and data from state entities are used in combination with catalogs from development and land use planning, Software for Geoprocesses and virtual tours, and cadastral information provided by the Decentralized Autonomous Government (GAD) of Santa Cruz to develop techniques that offer a risk index to identify buildings that could sustain seismic and tsunamic loads. The study exposes alarming results that would prevent the installation of photovoltaic generation systems on the buildings’ roofs. Consequently, a more detailed field study is recommended to contrast the reported analysis to implement mitigation strategies accordingly. Finally, geoprocesseced maps are presented, in addition to general installing recommendations for the photovoltaic system’s infrastructure.

1. Introduction

The Galapagos Islands, considered a natural sanctuary for their unique diversity of ecosystems and biological species, face a great challenge to supply sustainable electricity to its inhabitants. Until 2001, only power generation plants powered by fossil fuels were used on the islands, consuming 29% of the 5.78 million gallons of diesel transported from the continent, contributing large amounts of CO₂ to the atmosphere [1].

The primary precedent that marked the transition of the Galapagos Islands towards the use of green energy occurred on 20 January 2001 due to an environmental accident near the San Cristobal Island coast, where approximately 75,000 gallons of gasoline and 70,000 gallons of diesel were spilled into the Pacific Ocean [2]. This event generated several projects to implement renewable energies in the Islands, such as the Ergal Project, which implemented the Baltra wind farm, Puerto Ayora–Baltra photovoltaic plants, and battery storage systems [1]. In addition, several studies and strategies have been prepared that align with the goals of the 2015 Paris Climate Agreement to curb climate change and reduce the production of greenhouse gases until the year 2030 [3]. Indeed, the Galapagos Islands electricity master plan considers short and medium-term projects (2018–2027) proposed to reduce the energy dependence of continental Ecuador and strengthen the supply of clean energy [1,4].

Despite these initiatives, fossil fuels continue to be the primary source for producing electrical energy since renewable generation systems (e.g., photovoltaic and wind generators) are not currently able to be in line with the accelerated growth of the population and tourism, in addition to urban expansion and unsustainable construction systems. Therefore, it is necessary to introduce feasible techniques to achieve sustainable and resilient energy generation [5].

In this regard, due to the location of the Galapagos Islands and the high levels of solar radiation on the islands, photovoltaic energy (e.g., photovoltaic panels) emerges as an adequate solution [6]. Photovoltaic systems are one of the most competitive solutions to generate electricity in isolated areas [7,8]. They are expanding due to their easy application and installation in residences, businesses, and large-scale projects. Worldwide, 1003 TWh of photovoltaic energy was generated in 2021 and increased by 270 TWh in 2022 [9]. Solar PV accounted for 4.5% of total global electricity generation, and it remains the third-largest renewable electricity technology behind hydropower and wind [10].

On the one hand, distributed generation (DG) systems, including photovoltaic generation plants, allow the implementation of so-called microgrids. A microgrid is defined as a low- or medium-voltage system that comprises DG units, an energy storage system, an energy management system, and loads. A microgrid can operate in a grid-connected [11,12] or an islanded mode [13]. In this context, implementing microgrids in isolated locations, such as the case of the islands, is at its peak, observed, for instance, in the Pacific Islands, where panels are implemented on terraces of houses, tourist complexes, and even airports [14]. Additionally, in the Canary Islands, Tenerife contributes more than 50% of the photovoltaic energy of the electricity grid through solar plants with powers of 100 kW per plant [15], which is of great importance by reducing the external dependency on imported fossil fuel by 30% and consequently, the CO₂ emission gasses associated.

Another example is the Dominican Republic, which has one of Latin America’s largest solar power plants, with 198,000 photovoltaic panels that generate 54 MW [16]. Moreover, a successful case of sustainable energy can be seen on the Island of Gapa, located in the Republic of Korea, where its energy is 100% renewable. It is generated by two wind turbines and solar panels installed on the terraces of 49 of the 97 existing homes. The island produces 674 kW, of which only 230 kW [17] are consumed. Finally, as described in [1], Ecuador has ten renewable power plants installed in the Galapagos Islands, producing 7.27 MW of effective power in 2021. However, to achieve the resilience of photovoltaic systems installations, it is necessary to identify their weaknesses through a methodology that includes data collection, risk assessment, and implementation of strategies and policies [18].

In this context, the Galapagos Islands are prone to earthquakes and tsunamis. Regarding the seismic risk that accounts for the probability of experiencing losses induced by earthquakes at a given site during a period of interest [19], in the Galapagos Islands, interplate earthquakes are recorded in the collision zone between the Nazca and Cocos plates [20]. Tectonic faults cause 90% of the earthquakes produced in the archipelago. The remaining 10% are of volcanic origin or magma movement since the islands are on top of a hot spot. These earthquakes are usually of low magnitude. However, a 6.3 Mw (Richter scale) event stood out in 1954 [21].

Regarding the tsunami risk, due to their geographical location, the Galapagos Islands are susceptible to tsunamis, whether caused by earthquakes in continental Ecuador or those that occur anywhere in the Pacific, coming from the various existing subduction faults [22]. Indeed, the islands could be stricken by far- and near-field tsunamis, accounting for 75% and 25%, respectively [23]. A clear example is the 9.0 Mw tsunami in Japan in 2011, which recorded a maximum elevation in the ocean’s water level of 4.80 m and a flood length of 129.50 m on Santa Cruz Island with a wave arrival of 5 to 6 h [24].

Installation of rooftop PV systems requires knowledge of several factors, such as the PV panel’s optimal tilt angle and orientation, the seismic forces to which the solar panels and their infrastructure are exposed, and the minimum separation between the panels to avoid possible shadows, among others [25].

The optimal inclination ranges from 0 to 30 degrees. In contrast, the orientation depends on the site’s location concerning the equator. Places in the northern hemisphere should install their panels facing south. In contrast, areas in the southern hemisphere use a northerly orientation [26]. In Ecuador, the sun’s rays hit practically perpendicularly, so solar panels and their accessories must be placed at an inclination angle between 7 and 19 degrees to guarantee self-cleaning and cooling and avoid accumulating water, dust, or ashes [27].

The technical criteria for installing photovoltaic systems infrastructure is based on the Section 13 of the ASCE 7-16 code. Each panel is seismically designed to prevent impact, instability, or loss of support. The code provides data necessary to calculate the seismic load paths for attached and unattached photovoltaic systems infrastructure, friction resistance, minimum separation between adjacent unattached panels, and the distance between the edges and offsets of roof surfaces for ballasted and non-ballasted solar panels [28].

This study presents the earthquake and tsunami risk assessment of existing buildings in the main city of Santa Cruz Island, Puerto Ayora. As a pilot study, the purpose is to identify structures for future implementation of renewable generation systems on buildings’ rooftops based on photovoltaic isolated microgrids in the Galapagos Islands; thus, providing a sustainable and resilient energy solution against tsunamis and earthquake hazards. The analysis is based on the FEMA P-154 [29] and FEMA P-646 [30] methodologies.

The main original contributions from this study are listed as follows:

• Hazard, exposure, vulnerability, and risk index maps due to earthquakes and tsunamis for 517 Puerto Ayora—Santa Cruz Island studied properties using the FEMA P-154 and FEMA P-646 methodologies.
• Quantification of earthquake- and tsunami-vulnerable buildings and the principal factors causing high-risk indexes.
• General recommendations to install photovoltaic systems infrastructure on identified non-vulnerable buildings.

The rest of the paper is organized as follows. Section 2 explains the methods used to estimate the hazard, exposure, vulnerability, and risk due to seismic and tsunami events by applying the FEMA P-154 and FEMA P-646 methodologies. Section 3 presents the results, such as the seismic zone, maximum earthquake spectrum considered, seismicity region, and maps. Section 4 discusses the achieved results. Finally, Section 5 presents the main conclusions from this work.

2. Methods

Firstly, the risk represented by earthquakes and tsunamis is determined to define the buildings that meet the sustainability factors for installing photovoltaic systems based on isolated microgrids.

2.1. Earthquake Risk

The identified earthquake risk estimates the damage and economic and human losses due to the impact of one or more seismic events with destructive potential [31]. A conventional methodology based on a classical perspective determines the consequences or effects, for which a qualitative and quantitative expression of risk is defined. The qualitative risk is defined as the product of the probability and the consequence characterized as low, moderate, or high [32,33,34]. In contrast, quantitative risk is defined as the combination of three elements: hazard (H), exposure (E), and vulnerability (V) expressed by R = H × E × V [32]. As summarized in Figure 1, the seismic hazard is the probability of experiencing a specific earthquake intensity at a particular location during a period; the exposure refers to the stock of infrastructure, their occupants, and the related economic factors exposed to earthquakes. The vulnerability evaluates the socioeconomic and environmental losses of the infrastructure exposed to earthquakes.

2.1.1. Earthquake Hazard

In this study, the seismic hazard is determined by the provisions of the Ecuadorian Construction Standard (NEC-2015) [36] that presents the peak ground acceleration (PGA) seismic hazard map for a 475-year return period with a 10% probability of exceedance in 50 years (V_s30 = 760 m/s) [31]. Then, the design spectrum is scaled by 1.50 to establish the maximum considered earthquake (MCE) with a return period of 2475 years [37].

2.1.2. Earthquake Exposure

It is necessary to identify a database of geographic location, physical characteristics, economic valuation, and type of human occupation [38]. Cadastral and census data, provided by the decentralized autonomous governments (GAD) and the National Institute of Statistics and Censuses (INEC), respectively, are used to register these data.

2.1.3. Earthquake Vulnerability

In this study, the FEMA P-154, Rapid Visual Screening of Buildings for Potential Seismic Hazards [29] is used, where a building is categorized as whether it reports low, medium, or high vulnerability based on a detailed visual analysis with data related to its seismic structural behavior [39].

The FEMA P-154 methodology [29] has two evaluation levels that yield scores that indicate the vulnerability of the building to a seismic event. The first level is based on a rapid visual evaluation or “survey from the sidewalk”, to identify typologies of the structural system, construction materials, occupation, soil type, construction data, geological risks, irregularities, adjacency, the danger of falling objects, and the considered building code. Each typology has a fundamental score representing the probability of building collapse in the face of an earthquake at a given time, which is affected according to the anomalies found during the evaluation [40]. The second level results after modifying the first level scores by elevation or plan structural irregularity modifiers and other deficiencies, e.g., lack of redundancy, pounding, or seismic retrofitting. With this result, the building is classified as not vulnerable or vulnerable to earthquakes for human safety. The latter case requires a more rigorous evaluation [41].

2.2. Tsunami Risk

As aforementioned, tsunamis are rare but potentially devastating natural hazards. Therefore, using probabilistic methods, tsunami risk analysis is fundamental to long-term planning and risk management in affected areas. The methodology aims to identify the probability of a tsunami striking a specific site in a defined time interval, determining heights, inundation distances, exposure, and vulnerability of existing buildings [42].

This study collects information from existing models and maps generated by the Oceanographic Institute of the Ecuadorian Navy (INOCAR) [42], which are built as follows.

2.2.1. Tsunami Hazard

INOCAR identified a scenario based on the historical data of tsunamigenic events registered in Ecuador that would generate a hypothetical maximum considered tsunami on the coasts of the insular region. This event is an 8.4 Mw magnitude earthquake, with a rupture zone off the coast of Manabí with coordinates 0°32′10.47″ South and 80°54′54.99″ West [43], as shown in Figure 2.

2.2.2. Tsunami Exposure

The same database and maps of the seismic risk section are used and complemented with building height data, bathymetric, and topographic data obtained from the Military Geographic Institute (IGM) [44].

2.2.3. Tsunami Vulnerability and Numerical Simulation

The evaluation of the effects of the hypothetical tsunami is calculated using the TUNAMI N2 model (Tohoku University Numerical Analysis Model for Investigation of Near Field Tsunami), which is part of the list of codes verified by the National Oceanic and Atmospheric Administration (NOAA) Center for Tsunami Research and has more than 80% certainty [43].

TUNAMI N2 numerical simulation solves nonlinear shallow water equations and elastic deformation models to determine seafloor deformation at a given seismic magnitude, orientation, dimension, and fault motion [45,46]. It is presented as follows:

$$\begin{array}{l}\frac{\partial \varphi }{\partial t}+\frac{\partial M}{\partial x}+\frac{\partial N}{\partial y}=0,\\ \frac{\partial M}{\partial t}+\frac{\partial }{\partial x}\left(\frac{M^2}{D}\right)+\frac{\partial }{\partial y}\left(\frac{MN}{D}\right)+gD\frac{\partial \varphi }{\partial x}+\frac{g{n}^{2}M\sqrt{M^2+N^2}}{D^{7/3}}=0,\\ \frac{\partial N}{\partial t}+\frac{\partial }{\partial x}\left(\frac{MN}{D}\right)+\frac{\partial }{\partial y}\left(\frac{N^2}{D}\right)+gD\frac{\partial \varphi }{\partial y}+\frac{g{n}^{2}N\sqrt{M^2+N^2}}{D^{7/3}}=0\end{array},$$

(1)

where ϕ is the wave height, D is the water depth, and M = uD and N = vD are the velocity fluxes in the x and y directions, respectively, with u and v being the velocities, g = 9.81 [m/s²] the gravity acceleration, and n the Manning roughness coefficient, n = 0.025 [s/m^1/3] [45].

In the model generated by INOCAR, a maximum tide of 1.86 m is assumed, a roughness coefficient of n = 0.025, and the effects of wind and gravity waves are not considered since the water level is supposed to be constant [43].

As a complement to the flood models and maps presented by INOCAR and the Risk Management Secretariat (SGR), the FEMA P-646 Guidelines for Design of Structures for Vertical Evacuation from Tsunamis [30] is applied. This methodology identifies buildings resistant to tsunamigenic events, which could qualify as temporary shelters and safe facilities for installing photovoltaic systems.

3. Results

3.1. Puerto Ayora Earthquake Hazard

The seismic hazard is determined based on what is established by the NEC-2015. Ecuador is classified into six seismic hazard zones per a Z factor representing peak ground acceleration measured as a fraction of the gravity acceleration, as depicted in

Table 1. Maximum expected acceleration in rock for the design earthquake [36].

Seismic Zone	I	II	III	IV	V	VI
Z factor 1	0.15	0.25	0.30	0.35	0.40	0.50
Seismic hazard characterization	Intermediate	High	High	High	High	Very High

¹ Z is expressed as a fraction of the gravity acceleration.

. The Galapagos Islands are categorized as a type III high seismic hazard zone with a peak ground acceleration of 0.30 g [47].

To build the acceleration design spectrum, the site (Fa), displacement (Fd), and soil (Fs) factors for Puerto Ayora—Santa Cruz are considered, as summarized in

Table 2. Data for spectrum design.

Variable	Definition	Value	Units
Z	Mapped design earthquake peak ground acceleration	0.30	g
Fa	Soil amplification coefficient considering site effects	1.25	-
Fd	Soil amplification coefficient considering displacement	1.19	-
Fs	Soil amplification coefficient considering soil behavior	1.02	-
To, Tc	Limits of the period domain in which the spectral acceleration reaches its maximum values $To=0.10\cdot Fs\cdot (Fd/Fa)$ $Tc=0.55\cdot Fs\cdot (Fd/Fa)$	0.10 0.53	s s
TL	Long-period transition period $T_L=2.40\cdot Fd$	2.86	s

.

The soil type is determined based on existing studies, where it is concluded that San Cristobal Island soil consists of basaltic rock material [36]. Basalt has a minimum shear wave velocity of 271.27 and a maximum of 579.73 m/s. Considering the minimum rate, the soil is classified as type D, with a shear wave velocity between 180 and 300 m/s.

According to the current Ecuadorian Construction Standard, the expressions used to build the design spectrum are provided as follows:

$$S_a=\left\{\begin{array}{ll}Z\times Fa\times \left(1+(\mathsf{\eta }-1)\times \frac{T}{T_0}\right)\hfill & 0\le T<T_0\hfill \\ \mathsf{\eta }\times Z\times Fa\hfill & T_0\le T<Tc\hfill \\ \mathsf{\eta }\times Z\times Fa\times {\left(\frac{Tc}{T}\right)}^r\hfill & T\ge Tc\hfill \end{array}\right.,$$

(2)

where η is the ratio between the spectral acceleration S_a (i.e., fundamental period of the structure T = 0.1 s) and the PGA for the selected return period, and r is the factor used in the design spectrum concerning the type of soil for this case study for type D soils with a value of 1. These expressions are presented in Figure 3.

To determine the seismic hazard characterization, the values of Ss and S₁ are determined for periods of 0.20 and 1.00 s, respectively. These values are obtained concerning the MCE. Furthermore, Figure 4 shows the elastic design spectrum and the MCE spectrum with the acceleration values obtained for Ss and S₁.

For the accelerations, Ss = 1.45 g and S₁ = 0.93 g, a “High” and “Very High” level of seismic threat is considered, as established in

Table 3. Seismicity region determination for the MCE [39].

Seismicity Region	Spectral Acceleration Response Ss (Short Period or 0.2 s)	Spectral Acceleration Response S1 (Long Period or 1.0 s)
Low	Ss < 0.250 g	S1 < 0.100 g
Moderate	0.250 g ≤ Ss < 0.500 g	0.100 g ≤ S1 < 0.200 g
Moderate-High	0.500 g ≤ Ss < 1.000 g	0.200 g ≤ S1 < 0.400 g
High	1.000 g ≤ Ss < 1.500 g	0.400 g ≤ S1 < 0.600 g
Very High	Ss ≥ 1.500 g	S1 ≥ 0.600 g

. For this reason, the most critical seismic region is adopted, thus choosing “Very High”.

Next, Figure 5 shows the seismic hazard map for Puerto Ayora buildings on Santa Cruz Island. The orange represents the analyzed buildings, the white represents the existing properties, and the green shadow indicates the seismic hazard region considered “Very High”.

3.2. Puerto Ayora Exposure

Figure 6 shows the exposure map where information provided by the GAD displays different lots and their occupation types, such as housing, educational, medical, churches, police, statewide, and recreational. This study focuses on homes, apartments, hotels, and hostels. Houses are represented in pink, apartments in green and blue, and hotels and hostels in light green, cyan, and beige.

3.3. Seismic Vulnerability of the Santa Cruz Island

Before applying the FEMA P-154 methodology, a sample of buildings is obtained. With 238 hectares, Puerto Ayora has 2361 properties, and the El Mirador Urbanization, with 70 hectares, has 1133 properties. That is, there are a total of 3764 lots [48].

The sample size, k, is computed with a confidence level of 95% and a margin of error of 5% using Equation (3) as follows:

$$k=\frac{N_k\cdot Z_k^2\cdot p_k\cdot (1-p_k)}{e_k^2\cdot (N_k-1)+Z_k^2\cdot p_k\cdot (1-p_k)}$$

(3)

where N_k is the population size, Z_k is the critical value of the normal distribution at the required confidence level, p_k is the sample portion, and e_k is the margin of error. As a result, a sample of 365 buildings corresponding to 517 properties is obtained.

Below,

Table 4. Vulnerability results of Puerto Ayora using FEMA P-154.

Typology	Description	Quantity Buildings	Vulnerability	Percentage of Buildings
C1/C3	CMRF-CFUM	257	High: 0–2	49.71%
S3/C1/C3	LMF-CMRF-CFUM	58	High: 0–2	11.22%
S3/C3/URM	LMF-CFUM-UMWB	21	High: 0–2	4.06%
S3/S5	LMF-SFUM	3	High: 0–2	0.58%
URM/C3	UMWB-CFUM	1	High: 0–2	0.19%
URM/S3	UMWB-LMF	4	High: 0–2	0.77%
URM/S3/S5	UMWB-LMF-SFUM	2	High: 0–2	0.39%
W1	LWF	1	High: 0–2	0.19%
		2	Low: >2	0.39%
W1/C1/C3	LWF-CMRF-CFUM	63	High: 0–2	12.19%
W1/C3/URM	LWF-CFUM-UMWB	76	High: 0–2	14.70%
W1/S3	LWF-LMF	1	Low: >2	0.19%
W1/S3/S5	LWF-LMF-SFUM	1	High: 0–2	0.19%
W1/URM	LWF-UMWB	27	High: 0–2	5.22%
TOTAL		517		100.00%

CMRF: concrete moment resisting frame; CFUM: concrete frame with unreinforced masonry infill walls; UMWB: unreinforced masonry bearing-wall buildings; SFUM: steel frame with unreinforced masonry infill walls; LWF: light wood frame single or multiple-family dwellings; LMF: light metal frame.

presents the results for the 365 buildings and 517 properties once the rapid visual inspection form of the FEMA P-154 methodology is applied.

Furthermore, Figure 7 shows the qualitative vulnerability of properties in Puerto Ayora. The properties are represented in white, whereas buildings with low and high vulnerability are depicted in blue and red, respectively.

Figure 8 shows the quantitative vulnerability index of buildings. The buildings in red exhibit indexes ranging from 0.1 to 1.00, those in yellow from 1.00 to 2.00, and buildings in green indexes greater than 2.00, indicating they are not vulnerable. Consequently, structures with an index lower than 2.00 require more detailed evaluation, as shown in

Table 5. Buildings of Puerto Ayora—Santa Cruz.

Vulnerability	Structures Quantity	Actions to Take
Structures that do not exceed the limit of ≥2	514	Requires a detailed assessment
Structures that exceed the limit of ≥2	3	Non-vulnerable structures

, which presents the number of buildings that need assessment by a specialist following FEMA P-154 guidelines.

Finally, the evaluated building risk index is calculated. The results are presented in

Table 6. Seismic risk index of Puerto Ayora—Santa Cruz.

Risk Index R = H × E × V	Number of Buildings	Percentage of Buildings
0.03	3	0.58%
0.09	4	0.77%
0.12	2	0.39%
0.15	69	13.35%
0.18	132	25.53%
0.21	3	0.58%
0.27	299	57.83%
0.33	2	0.39%
0.81	1	0.19%
0.99	2	0.39%
TOTAL	517	100.00%

.

Figure 9 shows the seismic index map of Puerto Ayora, Santa Cruz. Buildings in red to yellow indicate a high-risk index with values ranging from 0.03 to 0.33. In contrast, buildings in green report a low-risk index with values from 0.81 to 0.99, representing only 0.58% of the total existing infrastructure.

3.4. Vulnerability to Tsunami Santa Cruz Island

The vulnerability map in Figure 10 is based on a simulation with a maximum considered scenario for an 8.6 Mw earthquake off the Ecuadorian coast. As a result, waves up to 10 m high are obtained with a flood of approximately 20% of the city. The arrival of the waves is expected to be in an hour and a half [47].

Finally, Figure 11 presents the earthquake and tsunami risk map in Puerto Ayora, Santa Cruz Island, identifying the most vulnerable buildings with a risk index less than or equal to 0.33 and located in the maximum considered tsunami inundation area. Regarding qualitative tsunami vulnerability, buildings with low vulnerability are situated within the beige inundation area, while those with high vulnerability are in the red inundation area.

4. Discussion

In Puerto Ayora, Santa Cruz Island, a very high seismic hazard is visualized for an MCE with accelerations Ss and S₁ of 1.45 g and 0.93 g, respectively. According to the seismic vulnerability analysis of 517 properties corresponding to houses, apartments, hotels, and hostels, it is identified that 476 buildings, that is, 92.07%, are within the classification of concrete frames resistant to moments (C1) and concrete structures with unreinforced masonry (C3). The data are consistent with the type of structural system used in Ecuador, where reinforced concrete frames with confined masonry are the most common in housing construction [49].

It is identified that 99.42% of the buildings, corresponding to 514 units, report a high vulnerability index since they do not reach the minimum score of 2.00 established by the FEMA P-154 methodology, for which a seismic design specialist requires a more detailed evaluation. The study can be complemented with a field seismic analysis to determine vibration periods and story drifts [37].

From the 2016 earthquake, it is possible to collect extensive information on the existing seismic vulnerability in Ecuador, including that the buildings have poor seismic performance since the moment-resistant frames are highly flexible, causing damage to both structural and masonry elements. It should also be noted that the low quality of the materials, the lack of supervision during the construction processes, and the unforeseen increases in the construction area play a fundamental role when defining seismic vulnerability and can be causes of fatalities, damages, or collapses [49,50,51,52].

Another cause of the low values obtained is the delayed official country’s seismic regulations until the 2015 code, in which it was required by law that buildings comply with seismic design requirements to safeguard the life of their occupants [49].

In addition, as part of the last step of seismic risk management, it is necessary to implement protection and mitigation strategies, such as generating reinforcement plans where the seismic and tsunami capacity of the structures is improved. Hence, using more reliable structural systems, such as dual systems, is recommended [35,49,51].

Several buildings are among low and high-risk flood zones regarding the tsunami events. Although the GAD has evacuation programs and alert systems, it should also be considered to include protection, accommodation, and relocation strategies for vulnerable infrastructure. These may include artificial or natural mitigation barriers, building adaptation, and land use restrictions [53]. In addition, FEMA P-646 recommends that buildings have a structural system capable of withstanding the extreme forces of earthquakes and tsunamis. In this sense, ductile systems are recommended that include open distributions allowing water flow, if possible, with an orientation that minimizes the potential effects of tsunami load and meets the minimum height required to be considered as a vertical evacuation shelter [30,54].

For installing resilient photovoltaic systems on roofs, only three buildings are non-vulnerable to earthquakes and tsunamis (corresponding to 0.58% of the structures studied). This percentage is meager. Therefore, a more detailed field study is recommended to identify missing information and possibly increase the number of specified buildings to install sustainable renewable energy solutions, thus reducing the consumption of fossil fuels on Santa Cruz Island.

Finally, photovoltaic systems installation should be in charge of certified professionals to provide a system capable of withstanding seismic and tsunami-based demands. Although ballasted solar panels can be installed without direct attachment, avoiding damage to the surface of planar roofs, this would be only permitted in structures up to six stories high, with a maximum roof slope of 1 in 20, and falling under risk categories I, II, and III [25,28,55].

5. Conclusions

This study presented the risk assessment analysis for earthquakes and tsunamis, enabling the installation of resilient photovoltaic generation systems in Puerto Ayora buildings in Santa Cruz Island—Galapagos, Ecuador. It was identified that Puerto Ayora is in a very high seismic risk zone, which, together with its deficient structural systems, causes 99.42% of its buildings to be vulnerable to a maximum considered earthquake. Regarding the tsunami risk assessment, it was determined that several buildings are in high-risk areas. A maximum considered tsunami is expected with waves of up to 10 m, with a wave arrival of 90 min and an approximate flooding of 20% of the city. In this regard, the participation of government institutions to demand compliance with national and international seismic codes and land use restrictions in vulnerable areas is essential. In addition, it has been verified that it is necessary to generate reinforcement and risk management programs to reduce possible impacts due to earthquakes and tsunamis. Indeed, only 0.58% of the buildings in Puerto Ayora meet the sustainability requirements for installing resilient photovoltaic generation systems, requiring more detailed field engineering analysis. Finally, a certified professional should verify the absence of structural deficiencies to ensure an efficient structure for installing photovoltaic systems, guaranteeing that the assembly system and the photovoltaic panels will not be damaged under extreme events.