Spatial Distribution Of Damage Research Articles

SPATIAL ANALYSIS OF BROWN SPIDER MITE (Oligonychus punicae Hirst) DAMAGE IN AVOCADO USING SPATIAL ANALYSIS BY DISTANCE INDICES (SADIE)

Avocado (Persea americana Mill.) is a perennial crop that belongs to the Lauraceae family. This crop is affected by various pests, the most important of which is the spider mite Oligonychus punicae Hirst (Acari: Tetranychidae), also known as the brown avocado spider. The damage begins with reddish spots that spread throughout the leaf, eventually tanning the foliage and staining the fruit, resulting in its rejection in the market. As a result, understanding its spatial distribution is critical for growers to plan and implement integrated pest management programs effectively, reducing their economic and environmental impacts. This study used spatial analysis by distance indices (SADIE) to determine the spatial distribution of damage to the Hass avocado crop caused by brown spider mite populations in Coatepec Harinas and Donato Guerra, two municipalities in the State of Mexico, Mexico. Spatial behavior allows for the development of preventive or corrective control measures for the use of precision farming techniques. Spatial distribution maps were created using the geostatistical technique of ordinary Krigeing, and the mean and variance of damage caused by the brown spider mite in avocado were examined. The findings revealed a clustered spatial distribution with several aggregation centers that shift over time and correlate with the plots’ terrain and climate. No homogeneous pattern was found in any plot, indicating the need to continue this type of research to better understand concentration conditions and implement specific actions in the field.

A discrete-to-continuum model for the human cornea with application to keratoconus.

We introduce a discrete mathematical model for the mechanical behaviour of a planar slice of human corneal tissue, in equilibrium under the action of physiological intraocular pressure (IOP). The model considers a regular (two-dimensional) network of structural elements mimicking a discrete number of parallel collagen lamellae connected by proteoglycan-based chemical bonds (crosslinks). Since the thickness of each collagen lamella is small compared to the overall corneal thickness, we upscale the discrete force balance into a continuum system of partial differential equations and deduce the corresponding macroscopic stress tensor and strain energy function for the micro-structured corneal tissue. We demonstrate that, for physiological values of the IOP, the predictions of the discrete model converge to those of the continuum model. We use the continuum model to simulate the progression of the degenerative disease known as keratoconus, characterized by a localized bulging of the corneal shell. We assign a spatial distribution of damage (i.e. reduction of the stiffness) to the mechanical properties of the structural elements and predict the resulting macroscopic shape of the cornea, showing that a large reduction in the element stiffness results in substantial corneal thinning and a significant increase in the curvature of both the anterior and posterior surfaces.

Laminated Steel Fiber-Reinforced Concrete Hingeless Arch: Research on Damage Evolution Laws

In the context of reinforced concrete (RC) arch bridges, while the incorporation of full sections of steel fibers can enhance the bridge’s toughness, cracking resilience, and bearing capacity, achieving an optimal balance between structural performance and economic viability in this manner remains challenging. This article introduces a novel computational approach—the distributed steel fiber concrete (LSFRC) arch—which considers the spatial distribution of damage in RC arches. The static performance of SFRC elements and LSFRC beams was compared and analyzed using the concrete plastic damage model (CDP) in ABAQUS software. This study validated the rationality of the model and investigated the impact of varying steel fiber volume ratios and steel fiber layer heights on the damage evolution of LSFRC arches. The results of this study demonstrate that the cracking load and bearing capacity of an RC arch can be effectively enhanced through the addition of steel fibers to a local area under static loading. Furthermore, the deflection and damage to the arch waist and arch roof can be significantly reduced. Furthermore, the incorporation of steel fibers at an increased volume rate and at a greater height within the doped section can effectively slow the rate of damage evolution within the section. This results in the inhibition of crack extensions and in an improvement in the ductility and reliability of the damage stage. The LSFRC arches offer superior economic and practical advantages over their full cross-section doped steel fiber (FRC) counterparts. This study offers novel insights and methodological guidance for the design and implementation of concrete arch bridges.

Exploring freeze-thaw damage distribution of asphalt mixture through DIC in combination with CT

Open graded friction course (OGFC) is highly susceptible to environmental impacts such as load and clogging, due to its rich void structure and exposure to environments. Especially in cold regions, freeze–thaw (F-T) damage is inevitable for OGFC. While the existing analysis methods cannot specifically describe the material's micro-response to load or environment. Therefore, the digital image correlation (DIC) in combination with computed tomography (CT) was applied to closely examine the intricate process of F-T damage of OGFC in this research. Principal strain and strain energy were used to describe the F-T damage process and distribution. In addition, the effects of initial void content and immersion conditions on the temporal and spatial distribution of damage were discussed. The data demonstrated that the spatial distribution of F-T damage strain was uneven. During F-T cycles, the principal strain inside the OGFC during F-T cycles was generally increased, and the deformation of the sample gradually accumulated. According to the strain energy growth rate variation, the F-T damage could be divided into two stages during the 18 F-T cycles, namely, the development stage and the deceleration stage. Moreover, the crucial parts of F-T damage were determined to be at the end of the voids connected with the outside or the void interface between the aggregates and asphalt mortar. The larger initial void content would increase the strain of OGFC during F-T cycles, as well as the inhomogeneity of the strain. Furthermore, the strain energy increased considerably, and the development of F-T damage of OGFC accelerated. Under partial immersion conditions, the immersed part has large strain and strain energy due to the direct effect of F-T, and the increase in immersion depth aggravates the F-T damage.

Seismic performance of buildings during the magnitude 7.3 Kermanshah, Iran earthquake

In this paper, the findings and data of a large-scale reconnaissance mission following the November 12, 2017, M7.3 Kermanshah earthquake near the Iran-Iraq border are presented. The earthquake affected multiple cities in both countries and led to widespread damage and notable casualties and fatalities. The highest peak ground acceleration was recorded in Sarpol-e Zahab at 0.7g. As part of two trips, the data on nearly 1200 buildings in eight cities were collected by devising a sampling scheme to maximize the coverage of the survey, which was then employed to compile regional damage statistics. The spatial distribution of damage is presented for the entire region as well as various cities and neighborhoods in each city. The damage statistics are also disaggregated based on structural building, occupancies, and risk categories. The damage sustained by various categories of building components and contents is also assessed. In addition, the damage at the component level is closely examined for the structural and nonstructural components of severely damaged buildings to reveal the underlying causes that root in poor construction practices, lax enforcement of the building code, and inadequate seismic design provisions. Finally, the damage to hospitals in the region is investigated. This data, which can be augmented through a similar approach in the aftermath of probable future earthquakes, is key in calibrating the regional risk and resilience analysis of communities.

The Impact of Wind Characteristics on the Spatial Distribution of Damage to the Built Environment during Wildfire Events: The 2022 Marshall Fire

The Impact of Wind Characteristics on the Spatial Distribution of Damage to the Built Environment during Wildfire Events: The 2022 Marshall Fire

Collision damage quantification of RC pier columns coupling axial, flexural and shear effects

Reinforcement concrete (RC) pier columns are the main supporting elements of many highway bridges and city viaducts, therefore the health state of a pier column is critical to the safe operation of bridges. Vehicle-pier collision accidents, which occur increasingly frequently, often induce unexpected damage to an impacted pier column, threatening the safety of bridges. It is important to define appropriate damage indices that can be used to effectively assess the conditions of a pier column damaged by a vehicle collision in a quantitative manner. Previous researchers have proposed many types of damage indices to quantify the degree of damage to an RC column. However, the existing damage indices often suffer from limitations such as undefined upper- and lower-bound rules, ignorance of shear deformation, etc. This paper proposes a plasticity-based damage index, which uses the accumulation of plastic deformation to reflect the damage state of an impacted RC pier column. The proposed damage index ranges between 0.0 and 1.0 which can effectively couple axial, flexural and shear deformation of RC sections during vehicle collisions with detailed model validations using experimental data. A detailed parametric study is then conducted which shows that the damage index can very effectively trace the time-history and spatial distribution of damage on an RC pier column during vehicle collisions.

Spatially distributed damage in sandstone under stress-freeze-thaw coupling conditions

In the present study, we tried to understand the spatially distributed damage in sandstone samples under the coupled stress-freeze-thaw (SFT) conditions. Firstly, uniaxial compressive stresses (i.e. 0 MPa, 10 MPa, 20 MPa, and 25 MPa) were applied to the samples, and then freeze-thaw (FT) cycles (0, 8, 16, and 24) were performed on the uniaxially stressed samples to realize the SFT coupling. Next, real-time CT scanning was conducted to observe the induced damage. The total porosity was introduced to quantitatively evaluate the damage degree. The local porosity variation, with the distance from the center of the sandstone sample, was analyzed to understand the spatial distribution of damage. Finally, the coupling effects of SFT on the damage gradient were discussed. The results indicate that the porosity rises with FT cycles, and the applied stresses can accelerate the increase in porosity. The damage increases exponentially with the distance from the center of the sample. The damage presents a spatial gradient distribution, not the commonly used uniform distribution in various studies. The damage gradient increases with FT cycles, and the increasing rate in damage gradient decreases at uniaxial stress of 0 MPa and 10 MPa first, but the increasing rate in damage gradient increases with FT cycles then at stress increasing to 20 MPa.

Local Site Effects Investigation in Durres City (Albania) Using Ambient Noise, after the 26 November 2019 (M6.4) Destructive Earthquake

Site characterization of metropolitan areas, especially after an earthquake, is of paramount importance for interpretation of spatial damage distribution and taking measures that assure realistic design actions to strengthen existing constructions and create new ones. Such a case is the city of Durres, Albania, that was hit by the disastrous earthquake of 26 November 2019 (M6.4). Significant differences in structural damage were observed throughout the city, despite its uniform epicentral distance (approximately 15 km); this could be either due to varying vulnerability of the affected constructions and/or to spatial variation of strong ground motion in the city, resulting from local site effects; the latter factor was investigated in this study. This was achieved by taking single station ambient noise measurements throughout the city, at approximately 80 sites. Ambient noise measurements are favorable, as acquiring ambient noise data is an easy and effective noninvasive approach within urban environments. Measurements were processed using the widely applied Horizontal-to-Vertical Spectral Ratio (HVSR) method, following the SESAME project (2004) guidelines. Their fundamental and dominant frequencies, fo and fd, respectively, were calculated and related to the iso-depth contours of the investigated area, as well as their corresponding amplitudes, Ao, and Ad. These experimental parameters and the HVSR curves were used to group all examined sites into classes with similar properties. This clustering provided a zonation map with four categories consisting of similar shapes and amplitudes, applicable to the city of Durres. This map can be utilized as a first level zonation of local site effects for the city. In addition, dynamic properties of soil profiles in selected sites were investigated and tested using 1D synthetic ambient noise data, based on the Hisada (1994, 1995) simulation method, and compared to experimental HVSRs in proximity to the selected sites. A comparison of the proposed four categories zonation map to the observed damage of the 26 November 2019, mainshock is attempted and evaluated. The four categories zonation map with similar expected local site effects proposed in this study can be used as a first level seismic microzonation of Durres. Undoubtedly, corrections for 2D/3D effects on ground shaking must be applied to sites lying in the edges of the Durres basin.

Settlements and angular distortions of shallow foundations on liquefiable soil

The extensive injury caused to buildings by liquefaction during past earthquakes, with the uneven spatial distribution of damage, raises the need for rapid predictive tools, applicable at a large scale, that comprehensively account for the properties of earthquake, subsoil and structure. A method is herein proposed to quantify the angular distortion of framed low-rise buildings based on a simple characterization of the above factors. The analysis moves from past literature criteria introduced to quantify the vulnerability of buildings under static conditions and extends their applicability to liquefaction assessment integrating parametric two-dimensional numerical analyses with recent literature predictive formulas and machine learning inference. The numerical calculation, performed for variable stratigraphic and mechanical characteristics of the subsoil, ground motion and equivalent flexural stiffness of the foundation, quantifies the role of each factor on the absolute settlement and angular distortion. Then the dependency on the different factors of the angular distortion is inferred with an artificial neural network, grouping parameters to limit the number of input variables and express results with charts that make prediction more accessible.

Positive Correlation between DYFI Intensity Data and Microzonation Site Classes for Ottawa, Quebec City, and the Metropolitan Area of Montreal

Abstract At the local scale, seismic risk is often poorly estimated when considering equal hazard values across any given community. Indeed, past damaging earthquakes have shown that site conditions, which may amplify or deamplify ground shaking, have an influence on the spatial distribution of damage in urban areas. In eastern Canada, Leda clay deposits from the old Champlain Sea are of particular concern for strong site effects in many parts of Quebec and Ontario. To capture the variability in seismic site response, microzonation maps characterizing average shear wave velocity for the upper 30 m of soil, and predominant resonance frequency have been developed for Montreal, Ottawa, and Quebec City. The maps derived from seismic and borehole measurements have been used to develop shake map scenarios but have not been validated, because there have not been any significantly large, close earthquakes in recent years, and because the seismograph network coverage is not adequate to provide a detailed picture of variations in shaking across a city. Nevertheless, all the three cities are in or near active seismic zones, and felt reports, although less accurate than instrumental data, are numerous and provide a dense dataset showing relative shaking levels across a region. Using intensity data for several moderate earthquakes collected largely via the Canadian internet “Did You Feel It?” page, we systematically compare reported shaking levels to soil conditions indicated by the microzonation maps. This study shows a clear correlation between high-reported intensities and soft soils for Montreal where the number of observations is the largest. The results suggest that intensity data collected via the internet and social media could provide a viable method for validating microzonation maps and shaking scenarios.

Depredation of Crop Caused By Monkeys nearby ShivapuriNagarjun National Park, Kathmandu, Nepal

Macaca mulatta, and Macaca assamensis are common monkeys in Nepal. The Macaca assamensis was categorized as ‘Vulnerable’ under IUCN Red List. The habitat of the monkey was disturbed because of human interference and hence the consequence is frequent damage of human’s properties. However, there was limited study regarding the crop damage caused by monkeys in Nepal. Therefore, this study was objectively conducted to assess the damages and their spatial distribution caused by Monkeys nearby Shivapuri-Nagarjun National Park and also find the causes of interface between humans and Monkey. Four sites were visited and 120 house hold survey was done to collect the primary data. The GPS coordinates of the spatial distribution of damages were recorded. Secondary information about the damages was collected from 2019 to 2022. Descriptive and statistical analysis like trend analysis, principle component analysis and mapping of distribution of damages was done. The result showed that, the highest damage of the maize at Nayagaun, Thulogaun with 650 Kg while this was the lowest around 280 Kg. Similarly, the highest maize damage at Naagarjun, Gufagairi, Sarung danda was 400 Kg while the highest record of crop damage at Raniban, Ichangu Narayan was 190 Kg. The distribution map showed that there were 12 locations of maize damage over 450 kg at Nayagaun, Thulogaun. Similarly, the map of Goldhunga showed 17 places having medium damage (120-350 kg), 28 places of low damage (50-120 kg) while the 5 places of very low damage (<50 kg). The principle component analysis showed the causes of interface between humans and monkeys. The use of catapult in Nayagaun, Thulogaun, shout and charge threat in Naagarjun, Gufagairi, Sarung danda and in Raniban, Ichangu Narayan were the most influencing factors of this interface. This research will be useful for scientific community and policy maker.

Spatial analysis of damage evolution in cyclic-loaded reinforced concrete shear walls

This paper introduces a probabilistic framework to quantify the spatial distribution of cracking and crushing in rectangular reinforced concrete shear walls at different drift ratios. In this research, a comprehensive probabilistic spatial analysis is conducted on an extensive collected database of reinforced concrete shear walls tested under the quasi-static cyclic loading. The database includes 235 images of 72 damaged walls with various geometry and material properties at different drift ratios between 0.0 and 4.0%. Various image processing filters are implemented to the images to highlight the wall areas that are more prone to cracking and crushing. Then, advanced statistical analysis is carried out at the post-processing phase in order to quantify the spatial distribution of the damage. The results of the probabilistic analysis are presented for three major classes based on the variation of the wall aspect ratio. The damage heat maps are produced for each class, which show the concentration and severity of the occurred damages. In the following, statistical mixture models have been used to formulate the spatial variation of the damage over the 2D space of the concrete shear walls. A set of nonlinear predictive equations are also proposed to predict the probability of cracking at any specific zones of the walls based on the wall drift ratio. A major contribution of this study is to propose a visual benchmark for the inspectors to predict the peak-experienced drift ratio of a damaged wall (especially after a terminated cyclic-load) based only on the ultimate spatial distribution of damages. Therefore, the presented framework plays a crucial role in determining the post-hazard status of reinforced concrete shear walls based on the prediction of the peak drift ratio.

Safety Evaluation of Arch Dam Subjected to Underwater Contact Explosion

The stability of an arch dam can be significantly damaged by an extreme underwater explosion. This study proposed a damage index for assessing the degree of local damage of an arch dam after the dam was subjected to an underwater explosion. The damage index was applied to assess local damage at the middle part of the dam, surcharge holes, and abutment. A model was developed to evaluate the stability of the entire dam based on the spatial distribution of damage and the damage on the base interface. Results showed that local explosion damage at flood discharge holes or abutments might cause instability of the arch dam. When the contact explosion action location is on the abutment, it only needs 310 kg to cause the overall damage of the arch dam, while when the action location is on the middle part of the dam, the quantity of explosive required is 2800 kg.

Numerical study on the attenuation of high-amplitude stress wave in rock bar along with rock damage evolution

The attenuation of high-amplitude stress waves in the rock and the rock failure caused by the stress waves have significance for vibration source analysis and rock engineering support design, where the interactions between the two deserve further study. In this paper, a FEM based numerical investigation on high-amplitude stress wave attenuation and rock damage evolution in one-dimensional rock bar is performed, aiming to understand the interaction between the variation of rock damage and wave attenuation. The numerical model is calibrated by experimental results. The spatial distribution of damage in rock bar is quantified by statistical windows. The effects of wave amplitude and heterogeneity index of rock on wave attenuation as well as the distribution of damage are analysed in details. The results indicate that the high-amplitude stress wave decays exponentially in the rock bar, and the attenuation of wave becomes significant as the incident wave amplitude increases. The incident wave amplitude corresponding to the lower limit of the amplitude effect is approximately 30% of the static compressive strength of rock, while that corresponding to the upper limit is the dynamic compressive strength of rock. Under the same incident wave amplitude, the attenuation of stress wave is more obvious in the rock with higher heterogeneity. The rock damage is quantified in a specific window, and its spatial distribution is described along with the movement of the window. The rock damage is concentrated in a region near the incident end. The damage development in space is consistent with that of high-amplitude stress waves and is more obvious in the models with higher heterogeneity. Findings in this work is helpful for the understanding of interaction between high-amplitude stress wave attenuation and rock damage and facilitate design and protection of rock engineering.

Rapid earthquake loss assessment based on machine learning and representative sampling

This article proposes a new framework for rapid earthquake loss assessment based on a machine learning damage classification model and a representative sampling algorithm. A random forest classification model predicts a damage probability distribution that, combined with an expert-defined repair cost matrix, enables the calculation of the expected repair costs for each building and, in aggregate, of direct losses in the earthquake-affected area. The proposed building representation does not include explicit information about the earthquake and the soil type. Instead, such information is implicitly contained in the spatial distribution of damage. To capture this distribution, a sampling algorithm, based on K-means clustering, is used to select a minimal number of buildings that represent the area of interest in terms of its seismic risk, independently of future earthquakes. To observe damage states in the representative set after an earthquake, the proposed framework utilizes a local network of trained damage assessors. The model is updated after each damage observation cycle, thus increasing the accuracy of the current loss assessment. The proposed framework is exemplified using the 2010 Kraljevo, Serbia earthquake dataset.

Fragmentation Pattern and Removal Mechanism of Concrete Subjected to Abrasive Water Jet Impact

Abrasive water jet (AWJ) breaking technology is suitable for the maintenance and repair of concrete structures, generating minimal dust, low tool wear, and no vibrations or selective destruction. The failure features and mechanisms of concrete subjected to AWJ impact are fundamental issues of AWJ breaking technology, which are also related to the safety and quality of engineering construction. Based on computed tomography (CT), scanning electron microscopy (SEM), and image processing technology, this paper studied the fragmentation pattern and removal mechanism of concrete under AWJ impact. The general failure characteristics and crack propagation law of concrete subjected to AWJ impact were described through AWJ impact concrete tests. The spatial distribution of damage in concrete subjected to AWJ impact can be divided into the intensive action zone, the transition zone, and the weak action zone. The removal mechanism of AWJ was discussed by comparing the impact performance of a pure water jet (PWJ) system. The results indicate that abrasive particles can cause cliff‐shaped fracture and lip‐shaped distortion in the aggregate part and flat fracture surface in the matrix part. There is no obvious crack in the interfacial transition zone (ITZ) due to the weakening of the water wedge effect.

An Integrative Model for the Dynamic Behavior of Brittle Materials Based on Microcracking and Breakage Mechanics

This study presents an enhanced integrative constitutive model for brittle materials subjected to dynamic loading by combining a micromechanics-based damage model and a breakage mechanics model. The damage model was used to describe microcracking, which captures the initial fragmentation of brittle solids due to growth of cracks until the material transforms into a granulated material. The dynamic behavior of the granulated material was described with a breakage mechanics model, which is activated when the damage level reaches a predefined critical threshold. The response of reference material boron carbide was simulated under confined/unconfined compression and ballistic impact loading conditions. The predictive capability of the integrative model was investigated by comparing the unconfined and confined simulation results with experimental data quantitatively and qualitatively. The simulations were also performed with an integrative model adopting a Drucker–Prager based two surface model to investigate the role of the granular material model on the macroscopic dynamic response. The two integrative models, which provided similar failure strength values under unconfined compression, predicted considerable different damage pattern in sphere impact simulations. A series of sensitivity simulations revealed that some critical granular model parameters strongly control the extent and spatial distribution of damage, and penetration resistance. The sphere impact simulations conducted with different impact velocities were able to reproduce various deformation features observed in previous experimental studies. The capability of the integrative model in capturing many aspects of the dynamic response of brittle materials under different loading conditions suggests that it can provide useful guidance for the design and development of next generation materials.

Site-specific ground motion modeling for a historical Cairo site as a step towards computation of seismic input at cultural heritage sites

Throughout time, the area of historical Cairo has been affected by several earthquakes from near and distant seismogenic zones. The maximum earthquake intensity reported in Cairo is VII, on the Modified Mercalli Intensity scale, due to the 1992 Cairo earthquake (Mw=5.9). About 212 Coptic and Islamic monuments were damaged. The spatial distribution of damage, suggests the occurrence of strong local site effects in combination with high vulnerability of the cultural heritage buildings. This study presents the application of a novel seismic hazard analysis approach at a local scale based on physics-based ground motion simulations. A site-specific multi-scenario seismic input (ground motion time histories and response spectra) is computed at a heritage building in Cairo, considering the local site effect. The seismic input is calculated in three steps: a regional scale analysis followed by a site-specific analysis and the combinations of the computed scenarios ground motion. In the regional scale analysis synthetic accelerograms are computed at the site bedrock. Then, the site-specific analysis is performed to calculate the site surface ground motions or response spectra considering the local site effect. Three earthquake scenarios have been considered, characterized by different locations, magnitudes, and fault configurations. The last step consists in the combination of the computed scenario ground motion into one single multi-scenario seismic input specific for the site of interest. This input is represented by spectral ordinates and their variability. For the engineering purpose of time history analysis, the method allows also to extract the computed site specific physics-based accelerograms, requiring no amplitude scaling nor filtering by magnitudes, distances, or site classifications, as usually done with real ground motion records.

Spatial distribution of damage affects the healing, growth, and morphology of coral.

Many predators and herbivores do not kill their prey, but rather remove or damage tissue. Prey are often able to heal or regenerate this lost tissue. If the prey are modular organisms (e.g., some plants and cnidarians), regeneration is frequently influenced by other modules interconnected to damaged ones. For example, many coral predators remove tissue from colonies consisting of many polyps, and these polyps often share resources with their neighbors. Thus, the distribution of tissue loss on a coral colony could affect the coral's response. I hypothesized that spatially aggregated damage might be slow to heal due to competing demands on nearby polyps. To explore the spatial patterns of corallivory and their implications, I conducted: (1) field surveys documenting the spatial distribution of lesions on corals; (2) field experiments testing the effect of the distance between lesions on coral tissue healing, skeletal growth, and morphology; and (3) field surveys relating corallivore presence to coral growth and morphology. In the field surveys, lesions were aggregated at multiple spatial scales, and most lesions had other lesions within 2cm. When lesions were near one another, coral tissue regeneration was depressed, although there was no effect on whole colony growth. After a year, however, linear extension was lower in the neighborhood of the lesions. Additionally, gastropod corallivores (Coralliophila violacea) with low movement decreased coral growth and increased coral topographical complexity. These results suggest that corallivores that create clusters of coral damage have a greater effect on coral growth and recovery from damage than corallivores that spread damage throughout the colony.