Hydrological control of large hurricane-induced lahars : evidences from rainfall , 1 seismic and video monitoring 2

12 The Volcán de Colima, one of the most active volcanoes in Mexico, is commonly affected 13 by tropical rains related to hurricanes that form over the Pacific Ocean. In 2001, 2013 and 14 2016 hurricanes Jova, Manuel and Patricia, respectively, promoted tropical storms that 15 accumulated up to 400 mm of rain in 36 hrs, with maximum intensities of 50 mm/hrs. 16 Effects were devastating, with the formation of multiple lahars along La Lumbre and 17 Montegrande ravines, which are the most active channels in sediment delivery on the S-SW 18 flank of the volcano. Deep erosion along the river channels and several landslides at their 19 side were observed, and damages to bridges and paved roads for the arrival of block-rich 20 fronts resulted in the distal reach of the ravines. Based on data from real-time monitoring 21 (including images, seismic records and rainfall data), the temporal sequence of these events 22 is reconstructed and analyzed with respect to the rainfall characteristics and the 23 hydrological response of the watersheds based on rainfall/infiltration numerical simulation. 24 Nat. Hazards Earth Syst. Sci. Discuss., https://doi.org/10.5194/nhess-2017-354 Manuscript under review for journal Nat. Hazards Earth Syst. Sci. Discussion started: 13 October 2017 c © Author(s) 2017. CC BY 4.0 License.


Introduction
In past recent years hurricanes have had catastrophic effects on volcanoes of the world triggering lahars (sediment-water gravity-driven flows on volcanoes).One of the most recent episode is represented by the 2009 Hurricane Ida in El Salvador that caused several landslides and debris flows from the Chichontepec volcano, killing 124 people, or by the 1998 Hurricane Mitch that triggered the collapse of a small portion of the inactive Casita volcano, originating a landslide that suddenly transformed into a lahar that devastated several towns and killed 2000 people (Van Wyk Vries et al., 2000;Scott et al., 2005).A similar event was observed in 2005 when tropical storm Stan triggered landslides and debris flows from the Toliman Volcano (Guatemala), causing more than 400 fatalities at Panabaj community (Sheridan et al., 2007).Other examples can be found at the volcanoes Pinatubo (Philippines), Merapi and Semeru (Indonesia), Soufriére (Montserrat), Mt. Ruapehu (New Zealand), where tropical storms and heavy rainfall seasons have triggered high-frequency lahar events (Umbal and Rodolfo, 1996;Cronin et al., 1997;Lavigne et al., 2000;Lavigne and Thouret, 2002;Barclay et al., 2007;Dumaisnil et al., 2010;Doyle et al., 2010, de Bélizal et al., 2013).
Volcán de Colima (19°31'N, 103°37' W, 3860 m a.s.l., Fig. 1), one of the most active volcanoes in Mexico, is periodically exposed to intense seasonal rainfalls that are responsible for the occurrence of lahars from June to late October (Davila et al., 2007;Capra et al., 2010).Rain-triggered lahars represent a very common process during the rainy season (June-October) at Volcán de Colima (Davila et al., 2007;Capra et al., 2010;Vazquez et al., 2016a).They usually affect areas as much as 15 km from the summit of the volcano, with resulting damage to bridges and electric power towers (Capra et al., 2010), and are more frequent just after eruptive episodes such as dome collapse emplacing block- and-ash flow deposits (Davila et al., 2007;Vázquez et al., 2016b).Several hurricanes commonly hit the Pacific Coast each year and proceed inland as tropical rainstorm reaching the Volcán de Colima area.In particular, on 2011, 2013 and 2015 Jova, Manuel and Patricia hurricane respectively triggered long-lasting lahars along main ravines, causing several damages on roads and bridges, leaven uncommunicated for few days several communities in a radius of 15 km from the volcano.
Previous work (Davila et al., 2007;Capra et al., 2010) analyzed the lahars frequency at Volcán de Colima in relation with the eruptive activity and the characteristics of rainfalls.Lahars are more frequent at the beginning of the rains season, during short (< 1 hour) stationary rainfalls, with variable rainfall intensities and with only 10 mm of accumulated rainfall.This behavior has been attributed to a hydrophobic effect of soils on the volcano slope (Capra et al., 2010).In contrast, in the late rain season, when tropical rainstorms are common, lahars are triggered depending on the 3-day antecedent rainfall and with intensities that increase as the total rainfall amount increases (Capra et al., 2010).The lahars record used for these previous studies was only based on seismic data.Since 2011 a visual monitoring system have been installed on Montegrande and La Lumbre ravines (Figure 1), based on which a quantitative characterization of some events (i.e type of flow, velocity, flow discharge, flow fluctuation) have been possible (i.e.Vázquez et al., 2016a;Coviello et al., under revision).The aim of the present paper is to better understand the lahars initiation processes and their dynamical behavior, especially during hurricane events, when more damages have been observed on inhabited area.In particular, the arrival time of main lahar's front/surge at the monitoring stations is here analyzed with respect to the rainfall characteristics (rain accumulation and intensity) in relation with the hydrological response of the watersheds based on rainfall/infiltration numerical simulation.The occurrence of discrete surges within lahars have been attributed to spatially and temporally distributed lahar sources, temporary damming, progressive entrainment of bed material or change in slope angle (i.e.Iverson 1997;Marchi et al. 2002;Takahashi 2007;Zanuttigh and Lamberti 2007;Doyle et al., 2010;Kean et al., 2013).Without excluding previous models, data here presented shows that main pulses within a lahar are not randomly distributed in time, and they can be correlated with rainfall peak intensity and/or watershed discharge, depending on the watershed shape and hydrophobic behavior subject to the antecedent soil moisture.The lahars triggered by the hurricanes Jova, Manuel and Patricia are here used as they correspond with the best documented events occurred during past years, and they will be also compared with an extraordinary hydrometeorological event occurred at the begin of the rain season (11 June, 2013) to better show the drastic change on lahar initiation due to the hydrophobic effect of soils at Volcán de Colima.Based on rainfall distribution over time for the analyzed events, a stormwater is here designed, whic can be used to run simulations prior to an event to have an estimation of the time arrivals of main pulses when weather forecast is available.The data here presented have important implication for hazard assessment during extreme hydrometeorological events as a complementary tool of an early warning system.The source area of lahars at Volcán de Colima corresponds to the uppermost unvegetated portion of the cone (Fig. 1 and 2a), with slopes between 35° and 20°, that also corresponds with an area of high connectivity, being prone to rills formation and erosive processes (Ortiz et al., 2017).The channels along main ravines have slopes from 15° up to 4° in the more distal reach, they are flanked by densely vegetated terraces, up to 15 m high in average, that consist of debris avalanche and pyroclastic deposits from past eruptions (Figs.2b and c) (Cortes et al., 2010;Roverato et al., 2011).Seven major watersheds from 2 to 14 km 2 feed the main ravines draining from the volcano on the southern side (Fig. 1).La Lumbre is the largest watershed, with a total area of 14 km 2 , and Montegrande is in average with the other catchments, with an area of 2 km 2 (Fig. 1).Beside the difference in total area, the Montegrande and La Lumbre watersheds are quite different in geometry.

La Lumbre and Montegrande watersheds
Montegrande catchment is elongated, with a maximum width of 800 m, 300 m in average.
In contrast, the proximal portion of the La Lumbre catchment includes all the NW slope of the cone, to then extent to a more elongated shape towards SW, being up to 1500 m in width.These differences in area and shape can be correlated with a different response in water discharge under a rainfall event.In circular drainages, as the proximal portion of the La Lumbre watershed, all points are quite equidistant from the main river so all the precipitation reaches the river at the same time, concentrating a large volume of water.In contrast, in a more elongate basin, lateral drainages quickly drain water on the main channel at different points but with a lower total discharge.The Gravelius's index Kg (Bendjoudi and Hubert 2002), which is defined as the relation between the perimeter of the watershed (P) and that of a circle having a surface equal to that of a watershed (A): is here estimated for Montegrande watershed and for the upper, circular portion of La Lumbre watershed obtaining values of 1.7 and 1.1 respectively.The lower the value, the more regular the basin's perimeter and the more prone it is to present high runoff peaks.
Based on these considerations, at La Lumbre watershed a larger volume of water concentrates along the main channel because of its larger surface and circular shape, but after a larger period of time respect to Montegrande ravine, where a minor volume of water quickly reaches the main drainage.

Lahar Monitoring at Volcán de Colima
In 2007, a monitoring program was implemented at Volcán de Colima.At the beginning, two rain gauges where installed to study lahar initiation (AR and PH sites, Figure 1) and lahar propagation was detected by the broadband seismic stations of RESCO, the seismological network of Colima University (Davila et al., 2007;Zobin et al., 2009;Capra et al., 2010).Afterwards, two monitoring station specifically designed for studying lahar are of low quality because of the abundant steam coming from the hot lahars since they originated from the remobilization of fresh pyroclastic flow deposits (Capra et al., 2016).
The 11 June 2013 event was perfectly captured by the camera installed at the MgMS site and the BB-RESCO recorded its seismic signal.
The seismic signal is here analyzed to detect the arrival of main flow fronts and discharge variation.For this, only the amplitude of the signal is considered, which can be correlated with the variation in the maximum peak flow discharge (Doyle et al., 2010;Vázquez et al., 2016a).The seismic record is here compared with the available images to identify the main changes in dynamic of the detected lahars.All the lahars here analyzed correspond to multi- description of these types of lahars is available in Vázquez et al. ( 2016a), here we focus on the number of main flow peaks and their arrival times (Table 2).

The hydrometeorological events
Hurricane Jova formed over the Pacific Ocean, hit the Pacific coast on October 12, 2011, as a category 2, and traveled inland toward Volcán de Colima.The hurricane arrived as a tropical storm at the town of Coquimatlán, just 10 km SW of the city of Colima with winds up to 140 km/h, and 240 mm of rain over 24 h (Fig. 3a).Severe damage was registered in inhabited area, including the city of Colima where floods damaged roads, bridges and buildings.
The 2013 Hurricane Manuel of category 1, hit the pacific coast during national holidays (Fiestas Patria) causing several damage to mountainous region in Guerrero state, triggering several landslides that caused up to 96 deaths and left several villages uncommunicated as thousands of tourists trapped at Acapulco and Ixtapa international airports.At Volcan the Colima rains started on September 15 and lasted for more than 30 hrs with more than 300 mm of accumulated rains (Fig. 3a).
The 2015 Hurricane Patricia was considered as the strongest hurricane on record to affect Mexico.The system starts to develop on 18 October over the Pacific Ocean, strengthened into a hurricane shortly after 00:00 GMT 22 October and early on 23 October it reached its maximum category of 5.But late on the same day, the system rapidly lost its strength.It Patricia and Manuel rainfalls show a similar behavior, with a progressive rain accumulation along 28-30 hrs; in contrast, during Hurricane Jova, 200 mm of rain accumulated in less than 15 hrs reaching a total of 240 mm during the following 13 hrs (Fig. 3a).These differences are more evident plotting the 10-min accumulated value normalized over the total accumulated rainfall (Fig. 3b).Average rainfall intensities calculated over a 10-min interval range from 32 mm/hrs to 37 mm/hrs for Manuel and Patricia events respectively and up to 43 mm /hrs for the Hurricane Jova (Table 2).Finally rainfall values were calculated at selected intervals (15 m, 30 m, 45 mm, 1, 3, 6, 12, 18, 24, 28 hr) to design possible storm rainfall distributions based on tropical rains associated to hurricanes recorded so far at Colima Volcano (Table 2).Considering the similar behavior of the Manuel and Patricia rainfalls, a stormwater can be designed considering their average values (Fig. 3c) (i.e.NRCS, 2008), based on which a forecast analysis can be performed, as will be discussed below.(Capra et al., 2010).In-situ infiltration tests were also performed based on which values of saturated conductivity were obtained in the range of 50 mm/h (nude soil) to 100 mm/h (vegetated) (Ortiz, 2017).Based on these observations, soils were classified between group A and B (Bartolini and Borselli, 2009).Curve Numbers for the vegetated terraces and for the nude soils were estimated in 75 and 80 respectively (in wet season, Hawkins et al., 1985;Ferrer-Julia et al. 2003).To perform simulation with the FLO-2D code, two polygons were traced to delimit the un-vegetated portion of the cone from the vegetated area of the watershed, and at each polygon the relative CN value was assigned.The simulated rain corresponds with the cumulative value calculated at 10 minutes interval (Fig. 3b).At the apex of each watershed a barrier of outflow points were defined to obtain the total values of the watershed discharge.The simulation was performed with a 20-m digital elevation model.

Results
During the Jova hurricane, lahars started in Montegrande ravine early in the morning of 12 October, 2011, around 07:20 GMT (here after all time is in GMT), after approximately 40 % of the total rain (240 mm) accumulated (Fig. 4a).The event lasted more than 4 hours, and three main peaks in amplitude can be detected in the seismic signal (Fig. 4a).In particular, the first two peaks are similar in amplitude (0.015 cm/s), separated by more than 2 hours of signal fluctuation.After less than one hour from the second peak, a single, discrete pulse can be recognized (0.05 cm/s in amplitude), followed by a "train" of lowamplitude seismic peaks that lasted for more than an hour.
Along the same ravine, an extreme event was recorded on 11 June, 2013.This event corresponds to an extraordinary episode and is here introduced to better discuss the hydrological response of the Montegrande ravine.It represents an unusual event at the beginning of the rainy season, considering the total accumulated rainfall of 120 mm in less than 3 hrs (Table 2), with maximum pick intensity up to 140 mm/hr (Fig. 4b).Based on the seismic record and the still images of the event, this lahar was previously characterized as a multi-pulse flow, with three main blocks-rich fronts (I, II and IV, Fig. 4c), with similar amplitudes (0.015-0.025 cm/s), followed by a main flow body consisting of a homogenous mixture of water and sediments (with a sediment concentration at the transition between a debris flow and an hyperconcentrated flow) (III, Fig. 4c) (Vazquez et al. 2016a).The last, more energetic pulse (0.042 cm/s) was accompanied by a water-rich frontal surge that was able to reach the lens of the camera (IV, Fig. 4c).Comparing the Jova and the 2013 event seismic records it is possible to note that in both events, the largest pulse corresponds with the last one.Flow discharge was estimated for the 2013 event, with a maximum of 120 m 3 /s value for the largest pulses (IV, Figure 4b) (Vazquez et al., 2016a).For the Jova event, the only visual data available are the images of the channel the day before and the day after the event, where a deep erosion of the channel is visible (Fig. 5), but comparing its seismic  For the Hurricane Patricia seismic data (from the geophone) and still images were recorded at the La Lumbre monitoring station.Based on these data, at approximately 21:22 a slurry flow is detected on the main channel (Fig. 7a).First pulses of hyperconcentrated flows were detected around 01:30 (24 October) which progressively increased in flow discharge and sediment concentration.Several front waves were observed during flooding (I and II, Fig. 7b) for which an average flow discharge of 80-100 m 3 /sec was estimated, and two main pulses arrived at 04:30 and 05:00, with 6 m-depth block-rich fronts and maximum flow discharge of 900 m 3 /sec (III, IV, V and VI, Fig. 7b).At around 05:40 the seismic record detected the arrival of a third pulse.Although no images were available, the amplitude of the last pulse (0.07 cm/s) suggests it was larger than those previously described.As observed for the three events recorded at Montegrande ravine, the largest pulse correspond again with the last one.
The results of rainfall simulations are plotted as a normalized curve of the total discharge, along with the normalized accumulated rainfall and its intensity (calculated over a 10-min interval) (Fig. 8).In the same plot, the arrival time of the main lahar pulses here analyzed is also indicated (red triangles, behavior.In both cases early slurry flows are detected after ~40% of the total rain is accumulated.The main flow pulses better correlate with the highest rain intensity values, which also correspond with maximum peaks in watershed discharge; the last, largest pulse corresponds with the maximum peak discharge of the watershed.In contrast, for the Patricia event, along the La Lumbre ravine, first slurry flows also starts after 40% or rainfall accumulated, but main lahar pulses fit better with the peaks watershed discharge.
Finally, analyzing the simulation in the Montegrande ravine for the June 2013 event, it is possible to observe a different behavior.The lahar starts as less than the 10% of rain is accumulated, and the main lahar pulses perfectly correlate with the peak rainfall intensities, and only the last largest pulse correlates with the watershed peak discharge.

Discussion
At present, several attempts to define lahar rainfall thresholds have been already carried out for different volcanoes (i.e.Lavigne et al., 2000;van Westen andDaag, 2005 Barclay et al., 2007), including Volcán de Colima (Capra et al., 2010).This study is mostly addressed to better predict the lahar evolution during extraordinary hydrometeorological event as hurricane, a common long-duration and large-scale rainfall phenomenon at tropical latitudes.In particular, we are interested in predicting the arrival of block-rich fronts that have caused several damages during past events.Based on the seismic and visual data gathered from the events here analyzed, it is possible to evidence which are the key factors in controlling the arrival of main lahars fronts.For Jova, Manuel and Patricia events, lahars started after the 40% of total rain accumulated, and apparently the timing for the initial Montegrande and La Lumbre ravines can be correlated with the different areas and shapes of the two catchments.In fact, due to its elongated shape (K G = 1.7) and small area (A = 2 km), the Montegrande watershed shows a quicker response between rainfall and discharge, with a rapid water runoff that concentrated at different point along the main channel (Fig. 1b).This behavior is much clearer for the June 2013 event, which occurred at the beginning of the rain season when soils on the lateral terraces of the ravines show a hydrophobic behavior (Capra et al., 2010).The simulation is not able to reproduce any watershed discharge at the beginning of the event, because the hydrophobic behavior of the soils inhibits the infiltration and the water runoff quickly promotes lahar initiation.During this event, the first lahar pulses perfectly match with the rainfall peak intensities (except for the last major pulse), starting from the very beginning of the rainfall event.In contrast, La Lumbre ravine has a wider, rounded upper watershed (K G = 1.1;A = 14 km 2 ) that is able to concentrated a larger volume of water before to turn SW in the main channel where lateral contribution can still increase water discharge.Even if rainfalls of hurricanes Manuel and Patricia show a similar behavior (Fig. 3), the catchment response of La Lumbre is clearly different with a pulsating behavior of lahars mainly controlled by the watershed discharge.
Nevertheless, for all the events here analyzed, the largest pulse corresponds with the last one recorded and it correlates with the maximum watershed discharge, pointing to a strong control of the catchments recharge in generating the largest and more destructive pulses.
Previous works correlated the occurrence of surges within a lahar to multiple sources, such as lateral tributaries along the main channel (i.e.Doyle et al., 2010) or due to the failure of temporary dams of large clasts in correspondence of an increase in rainfall intensity (Kean et al., 2013).Lateral tributaries are absent in both Montegrande and La Lumbre channels and, even if accumulation of clasts it is possible, no significant discontinuities of the channel bed can be observed upstream the monitoring sites.Based on data here presented, formation of pulses within a lahar is mostly controlled with the increase in water runoff that at a critical discharge rate mobilize a large volume of sediment where large clasts accumulate at its front.This is a well-documented mechanism (i.e.Iverson, 1997), but based on the model here proposed, the discharge rate is controlled by the watershed discharge that regulates the timing on the arrival of main pulses, depending on the rainfall behavior and the watershed shape.Nevertheless, the last pulse always is the largest in volume.This model is strictly related to migratory, long-duration and large-scale rainfall events hitting tropical volcanoes such as the Volcán de Colima.In fact, during mesoscale non-stationary rainfalls, typical at the beginning of the rainy season, lahars are usually triggered at low accumulated rainfall values and controlled by rainfall intensity due to the hydrophobic behavior of soils, and they usually consist of uni-pulse events with a single block-rich front that last less than one hour (i.e.Vázquez et al., 2016b).In perspective, the results here presented can be used to design an Early Warning System (EWS) for hurricaneinduced lahars, i.e. event triggered by long-duration and large-scale rainfalls.Most common pre-event or advance-EWSs for debris flows are based on empirical correlations between rainfall and debris flow occurrence (e.g., Keefer et al., 1987;Aleotti, 2004;Baum and Godt, 2009).The instruments adopted for debris-flow advance warning are those normally used for hydrometeorological monitoring and consist of telemetry networks of rain gauges and/or weather radar.The typical way to represent these relations is identifying critical rainfall thresholds for debris flow occurrence.The availability of both a large catalogue of events and a reliable precipitation forecast that could give the predicted amount of rainfall some hours in advance would allow the issue of an effective warning, at least in predicting the arrival time of the main lahar pulses.In addition, instrumental monitoring of in-channel processes can be used to validate a preliminary warning-condition triggered by wheatear forecast and/or rainfall measurements.

Conclusions
Real time monitoring of lahars at Volcán de Colima volcanoes reveal that watershed discharge is the key factor in controlling the arrival of main block-rich fronts during longlasting lahar triggered during tropical storms, and that the largest destructive pulses will arrive after the initial surging.For the 2015 Hurricane Patricia event the weather forecast predicted an estimated value for the total rainfall, as also the approximate time of its landfall.Based on the deigned storm obtained with the time rainfall distribution of the event here analyzed, it could have been possible to anticipate when lahars started along the La Lumbre ravine, and the arrival time of main pulses.Along the other ravines, that show a watershed similar to the Montegrande, it could have been possible to predict the arrival of at least the largest pulse.This information coupled with the real time monitoring could be a better tool for hazard assessment and risk mitigation.In fact, these findings can be used to implement an advance warning system based on the monitoring of a hydrometeorological process to issue a warning before a possible lahar is triggered.Table 1.Data collected for the events here studied.
activity were installed, in 2011 at the Montegrande ravine and in 2014 at La Lumbre ravine (MSMg and MSL respectively, Figure1).Both stations consist of a 12 m-high tower with a directional antenna transmitting data in real time to RESCO facilities, a camcorder recording images each 2-4 secs with a 704 x 480 pixels in resolution, a rain gauge coupled with a soil moisture sensor, and a 10 Hz geophone(Vázquez et al., 2016a;Coviello et al., under revision).The rain gauge (HOBO RG3) records rain accumulation at one-minute intervals.At Montegrande ravine seismic data are also obtained from a 3 component Guralp Nat.Hazards Earth Syst.Sci.Discuss., https://doi.org/10.5194/nhess-2017-354Manuscript under review for journal Nat.Hazards Earth Syst.Sci. Discussion started: 13 October 2017 c Author(s) 2017.CC BY 4.0 License.CMG-6TD broadband seismometer installed at 500 m upstream from the monitoring site, sampling at 100 Hz (BB-RESCO, Figure 1).Montegrande station detected lahars occurred during 2011 Jova and 2013 Manuel events, and lahars triggered during the 2015 Hurrican Patricia were only recorded by La Lumbre station (Table 1).In fact, in 2011 only MgMS site was operating (as the BB-RESCO station), and recorded the seismic signal of the lahar associated to Jova and Manuel.No images are available since both events occurred during the night.The LMS station starts to operate at the end of 2013 and was able to record the lahars associated to Hurricane Patricia along the La Lumbre ravine (images and geophone data).In contrast, in 2015 the MgMS was destroyed by pyroclastic flows during the 10-11 explosive activity, and in October 2015 the new station was still under construction.Only few pictures were acquired and they pulses events as classified by Vazquez et al. (2016a); they consist of long lasting lahars presenting several pulses each one characterized by a block-rich front followed by the main body and dilute tail showing continuous changes in flow discharges.A detailed seismic Nat.Hazards Earth Syst.Sci.Discuss., https://doi.org/10.5194/nhess-2017-354Manuscript under review for journal Nat.Hazards Earth Syst.Sci. Discussion started: 13 October 2017 c Author(s) 2017.CC BY 4.0 License.
landfalls around 23:00 GMT along the coast of the Mexican state of Jalisco near Playa Cuixmala, about 60 km west-northwest of Manzanillo.On the morning of the 23 October, Nat.Hazards Earth Syst.Sci.Discuss., https://doi.org/10.5194/nhess-2017-354Manuscript under review for journal Nat.Hazards Earth Syst.Sci. Discussion started: 13 October 2017 c Author(s) 2017.CC BY 4.0 License.2015 it continued to rapidly weaken as it moves on the Sierra Madre Occidental high relieves.At Colima town, up to 400 mm of rains accumulated along 30 hours since the morning of 23 October (Fig. 3a).Lahars along the Montegrande ravine were hot since they originated from the erosion of pyroclastic flow deposits emplaced during the 10-11 July 2015 eruption.Sever damages affected the Colima town and the volcano surrounding.A bridge along the interstate was destroyed leaving uncommunicated La Becerrara village and interrupting the traffic between Colima and Jalisco states.
Nat. Hazards Earth Syst.Sci.Discuss., https://doi.org/10.5194/nhess-2017-354Manuscript under review for journal Nat.Hazards Earth Syst.Sci. Discussion started: 13 October 2017 c Author(s) 2017.CC BY 4.0 License.To better understand the lahar behavior and duration during extreme hydrometeorological event at Volcán de Colima, rainfall simulations were performed with Flo-2D code(O´Brian    et al., 1993).The Flo-2D code routes the overland flow as discretized shallow sheet flow using the Green-Ampt or the SCS Curve number (or combined) infiltration models.For the present work the SCS Curve Number (SCS-CN, i.e.Mishra and Singh, 2003) was selected.With this model, the volume of water runoff produced for the simulated precipitation is estimated through a single parameter that summarizes the influence of both the superficial aspects and deep soil, including the saturated hydraulic conductivity, type of land use, and humidity before the precipitation event.A similar approach was already used for modeling debris flow initiation mechanisms (i.e.Gentile et al., 2006;Llanes et al., 2015).To apply the SCS-CN model, it is necessary to classify the soil in one of four groups, each identifying a different potential runoff generation (A, B, C, D; USDA-NRCS 2007).The watershed of La Lumbre and Montegrande ravines were subdivided in two main zone: the unvegetated upper cone and the main channel that consist of unconsolidated pyroclastic material with large boulders imbedded in sandy to silty matrix, and the vegetated lateral terraces.Lateral terraces consist of old pyroclastic sequences, with incipient soils and vegetated with pine trees and sparse brushes, with soils that show a hydrophobic behavior at the beginning of the rain season Nat. Hazards Earth Syst.Sci.Discuss., https://doi.org/10.5194/nhess-2017-354Manuscript under review for journal Nat.Hazards Earth Syst.Sci. Discussion started: 13 October 2017 c Author(s) 2017.CC BY 4.0 License.
signal with the 2013 lahar, and based on the classification criterion established for lahars at Volcán de Colima(Vazquez et al., 2016a)  each main peak corresponds to the arrival of flow surges or to block-rich fronts followed by the body of the flow.Fluctuation in seismic energy along the vertical component reflects variation in flow discharge.The lahar recorded during the Hurricane Manuel along the Montegrande ravine shows a similar behavior as described for the Jova event (Fig.6).As the event occurred during the night no images are available.Based on the seismic record from the BB-RESCO, lahars stated around 03:00, and lasted for seven hours.The event was characterized by five main pulses, which amplitude increases with time (0.012-0.025 cm/s), being the last one the larger in magnitude (0.04 cm/s).Based on the amplitude values, the first two peaks correspond to precursory dilute flow waves followed by the three main pulses with blockrich fronts(I, II and III, Fig 6).
Fig. 8).By comparing watershed discharge with rainfall intensity, a general correlation can be observed for the Montegrande basin during Jova and Manuel hurricane, contrasting with the June 2013 event, where the simulation is not able to reproduce watershed discharge during the first minutes of the event when most of rainfall is accumulated and maximum rainfall intensities are detected.For la Lumbre watershed a clear correlation between peak intensities and watershed discharge is not clearly observable.If the arrival times of the main lahars' pulses are considered, the events associated to the hurricanes Jova and Manuel along the Montegrande ravine show a similar Nat.Hazards Earth Syst.Sci.Discuss., https://doi.org/10.5194/nhess-2017-354Manuscript under review for journal Nat.Hazards Earth Syst.Sci. Discussion started: 13 October 2017 c Author(s) 2017.CC BY 4.0 License.
Nat. Hazards Earth Syst.Sci.Discuss., https://doi.org/10.5194/nhess-2017-354Manuscript under review for journal Nat.Hazards Earth Syst.Sci. Discussion started: 13 October 2017 c Author(s) 2017.CC BY 4.0 License.pulses correlate well with the peaks of the rainfall intensity for the Montegrande ravine, while for la Lumbre ravine they better match with the watershed discharge.Nevertheless for all analyzed cases, the largest pulses correspond with the last ones and correlate with the peak watershed discharge for all the analyzed examples.The observed difference between Nat. Hazards Earth Syst.Sci.Discuss., https://doi.org/10.5194/nhess-2017-354Manuscript under review for journal Nat.Hazards Earth Syst.Sci. Discussion started: 13 October 2017 c Author(s) 2017.CC BY 4.0 License.

Figure captions Figure 1
Figure captions

Figure 2
Figure 2. a) Panoramic view of the Volcán de Colima showing the unvegetated main cone mostly composed by loose volcanic fragments.b) Montegrande and c) La Lumbre ravines in the middle reach where it is possible to observe the main channel flanked by 10-15mhigh terraces mainly constituted by debris avalanche deposits.

Figure 4
Figure 4. a) Seismic record of the lahar triggered during the Hurricane Jova, on 12 October, 2011.b) Seismic record of the lahar triggered during the 11 June, 2013 events.Main pulses are indicated with roman letters.c) Images captures by the camera corresponding to the main lahar pulses as indicated in figure b.

Figure 5 .
Figure 5. Images showing the morphology of the channel at the monitoring site of the Montegrande ravine, a) the day before and b) the day after the Hurricane Jova.c) Topographic profiles showing that the channel was eroded 1.5 m in depth.

Figure 6 .
Figure 6.Seismic record of the lahar triggered during the Hurricane Manuel, on 15 September, 2013, recorded along the Montegrande ravine

Figure 8 .
Figure 8. Diagrams showing the main lahar pulses (red triangles) as detected from the seismic signal of the analyzed events in relation with the accumulated rainfall (dark line), rainfall intensity (10m/hr) (gray line) and simulated watershed discharge (blue line) for the following hidrometeorological events a) Jova; b) Manuel; c) 13 June, 2013; and d) Patricia.