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Article

The Michoacán Tsunami of 19 September 2022 on the Coast of Mexico: Observations, Spectral Properties and Modelling

1
Centro Interdisciplinario de Ciencias Marinas, Instituto Politécnico Nacional, Ave. IPN, s/n, Playa Palo de Santa Rita, La Paz 23096, Mexico
2
Shirshov Institute of Oceanology, Russian Academy of Sciences, 36 Nakhimovsky Prosp., Moscow 117997, Russia
3
Department of Fisheries and Oceans, Institute of Ocean Sciences, 9860 West Saanich Road, Sidney, BC V8L 4B2, Canada
*
Author to whom correspondence should be addressed.
Water 2023, 15(1), 164; https://doi.org/10.3390/w15010164
Submission received: 15 December 2022 / Revised: 19 December 2022 / Accepted: 27 December 2022 / Published: 31 December 2022
(This article belongs to the Special Issue Seismic Risk Assessment and Modelling alongside Coastal Territories)

Abstract

:
The Mw 7.6 earthquake of 19 September 2022 within the coastal zone of Michoacán, Mexico, generated a major tsunami that was recorded by six coastal tide gauges and a single offshore DART station. All seven instruments were located within 250 km of the source. No tsunami was detected at larger distances. Maximum wave heights were observed at Manzanillo (172 cm) and Zihuatanejo (102 cm). Numerical modelling of the event closely reproduced the coastal and offshore tsunami records and shows that the tsunami energy radiated seaward from the source as a narrow “searchlight” beam directed normal to the source and mainland coast. Estimates of the frequency content (“colour”) of the 2022 tsunami event, and that generated in 2017 by the much stronger (Mw 8.2) Chiapas earthquake further up the coast, reveal a marked difference in the tsunamigenic response. Whereas the 2017 tsunami was mostly long-period (“reddish”), with 87% of the total tsunami energy at periods >35 min, the 2022 tsunami was short period (“bluish”) with 91% of energy at periods <35 min. A noteworthy feature of the 2022 event was the seismically generated seiches observed at Puerto Vallarta, which had a recorded period of about 7 min, began immediately after the main earthquake shock, and persisted for about one hour.

1. Introduction

Tsunamis are one of the greatest threats to the Pacific coast of Mexico [1,2]. Sanchez and Farreras [3] list 21 tsunamis instrumentally recorded on this coast for the period of 1952–1985. Of these, 12 were from distant sources and 9 from local sources. All 21 events were based on pen-and-paper analogue records that limited the accuracy of estimated wave parameters, their application for tsunami modelling and for scientific investigation. The situation changed after a major upgrade of the Mexican tide gauge network in the middle of the 1990s. New digital instruments now allow the measurement of sea level variations with high spatial and temporal resolution. Ortiz et al. [4] used the digital tsunami records from the local Mw 8.0 Jalisco-Colima earthquake of 9 October 1995, to reconstruct the earthquake source parameters. Recently, Zaytsev et al. [5,6,7] examined tsunamis impacting the coast of Mexico from a number of major distant events (Chile 2010, 2014, 2015 and Tohoku/Japan 2011) and the local Chiapas tsunami of September 8, 2017. In all of these studies, the high-precision coastal tsunami observations were supplemented by open-ocean tsunami measurements from the Deep-ocean Assessment and Reporting of Tsunamis (DART) stations deployed offshore of Mexico. A comprehensive analysis of the combination of coastal and deep-water tsunami records enabled us to examine the transformation of tsunami waves as they approached the coast and to characterize the physical properties of the events.
On 19 September 2022, at 18:05:06 UTC a Mw 7.6 thrust fault earthquake occurred at the coast of Michoacán state, Mexico. The epicenter of the earthquake (18.367° N and 103.252° W) almost coincided with the epicenter of the catastrophic Mexico City earthquake (Mw 8.1) of September 19, 1985 (Figure 1) that killed several thousand people [8,9]. The earthquake generated a tsunami that spread regionally and was recorded by tide gauges along the Mexican coast and by DART 43412 (Figure 1). In the first reports, this event was designated as the “Coalcoman earthquake” (Mexican Nacional Seismologic Service) and the “Aguila tsunami” (National Oceanic and Atmospheric Administration, Pacific Marine and Environmental Laboratory, NOAA/PMEL), named after the nearest communities. The tsunami caused no noticeable damage or human casualties; a small inundation was observed only on the Michoacán coast near the earthquake epicenter. A preliminary report of the NOAA/PMEL Center for Tsunami Research of this event included data from Mexican stations, Manzanillo and Puerto Vallarta, data from DART 43412 (closest to the epicenter) and initial simulation results (https://nctr.pmel.noaa.gov/mexico20220919/ (accessed on 3 October 2022)). This contrasts with the impact of the nearby tsunamigenic earthquake of September 2017.
The main goal of our study was to analyze all available tide gauge records on the Pacific coast of Mexico and from open-ocean DARTs located nearby, to evaluate the statistical and spectral properties of observed tsunami waves, and to construct an effective regional numerical model reproducing actual properties of measured waves. The onshore and offshore parameters of the 2022 Michoacán tsunami are compared with those of other tsunamis recently recorded in this region, with particular focus on the September 2017 Chiapas tsunami [5,6,7].

2. Materials and Methods

We examined high-resolution records of the 2022 Michoacán tsunami in the tide gauges operated by the Institute of Geophysics, National Autonomous University of Mexico (UNAM). The tsunami signal could be identified in only six of the gauges (Figure 1, Table 1). All of these instruments previously also recorded the 2017 Chiapas tsunami [7]. In addition to the coastal data, we used the 1 min “Event mode” data from DART 43412 located offshore of Manzanillo, Mexico. These data were obtained from the National Centers for Environmental Information (NCEI), NOAA, Boulder, Colorado. Unfortunately, none of the other DARTs located in this region were in the “event mode” during the event.
All available records have been examined using the same data analysis procedures and tsunami detection methods described by [5,6,7]. We first checked all data, corrected instrumental errors, filled gaps and removed spikes. Because the quality of all tide gauge records and the bottom pressure record of DART 43412 was quite high, analysis of the data was straightforward. Tides were calculated by the least squares method and subtracted from the original records; the resulting residual time series were then used in all subsequent analyses. To suppress low-frequency sea-level fluctuations, mainly associated with atmospheric processes, and to simplify tsunami detection, we high-pass filtered the de-tided time-series using a 4 h Kaiser–Bessel (KB) window [10]. These filtered series were subsequently used to construct plots of tsunami records (Figure 2a) and in the f-t (wavelet) analysis (Figure 2b).

3. Observations and Statistics

The records of the 2022 Michoacán tsunami on coast of Mexico are shown in Figure 2a and the statistical parameters of the recorded waves, including wave arrival times, maximum wave heights and mean wave variance over a 4.5 h period, are presented in Table 1. The highest trough-to-crest wave heights were observed at Manzanillo (172 cm) and Zihuataneio (102 cm), the two stations closest to the epicenter. These heights are almost three times greater than the corresponding heights of 52 and 39 cm recorded at these two stations during the 2017 Chiapas earthquake [7]. Prominent tsunami oscillations were also recorded in 2022 at Acapulco (68 cm) and Lazaro Cardenas (67 cm). At Huatulco and Puerto Vallarta, the tsunami signal was visible but weak (13–17 cm; Table 1). At all other stations, this signal was below the background noise level. The observations reveal that the coastal area affected by the 2022 Michoacán tsunami was quite confined, and much less extensive than for the 2017 Chiapas tsunami (compare Figure 1 and Figure 3 in [7]).
The 2022 Michoacán tsunami waves were first recorded at Manzanillo at 18:23 UTC, i.e., only 18 min after the main earthquake shock. Nine minutes later the tsunami waves arrived at Lazaro Cardenas and then, another six minutes later, at Zihuatanejo. For all three coastal stations, the tsunami signal arrived earlier than at open-ocean DART 43412 (Table 1). Propagating further, the tsunami waves arrived at three other stations. The last station, Huatulco, recorded the tsunami at 19:42 UTC, 1 h and 37 min after the main shock. The observed arrival times were in good agreement with the theoretical tsunami travel times (Figure 1) computed numerically according to the method of Fine and Thomson [11]. The duration of the tsunami ringing at all stations, measured relative to the background noise level, was a relatively short 16–18 h. For comparison, the tsunami ringing at the Mexican coast that followed the distant Chilean tsunamis of 2010, 2014 and 2015 [5] and the distant 2011 Tohoku tsunami [6] lasted for several days. Ringing after the near-field 2017 Chiapas tsunami lasted for about 1–1.5 days [7].
The sign of the first wave at all seven of the stations we examined was positive (the crest wave arrived first). This indicates that the entire initial tsunami source area was likely positive. Following [5], we also calculated an ”observed tsunami variance” as a measure of the tsunami energy along the coast. The variance parameter was evaluated in 6 h tsunami segments, starting with the wave arrival (see the corresponding column in Table 1). Maximum variances were at Manzanillo (966 cm2) and Zihuatanejo (435 cm2), while the minimum variance values were at Puerto Vallarta (24 cm2) and Huatulco (17 cm2).
A noteworthy feature of the 2022 event was the seismic seiches observed at Puerto Vallarta. These seiches, with a recorded period of about 7 min, began immediately after the main earthquake shock and lasted for about one hour (Figure 3). The measured seiches amplitudes were up to 20 cm; however, the actual amplitudes were probably much higher if we take into account the low-frequency filtering effect of the coastal tide gauges (see, for example, [12]). In particular, seismic seiches induced by the 2011 Tohoku earthquake in Norwegian fjords, as estimated from film clips, had amplitudes of 50–75 cm and periods of about 100 s [13]. Earthquake generated seiches associated with major seismic events are well known [14,15,16], but also rare compared, for example, with seiches generated by meteorological disturbances [17].
It appears that the marked seismic seiches observed at Puerto Vallarta were determined by the resonant properties of the port area The port is strongly sheltered from wind waves and has a narrow entrance and, as a result, a high Q-factor. The 7 min seiche period is the fundamental period of the port; the corresponding spectral peak for these motions is consistently observed in tsunami and background spectra for the site [5,6,7]. This period is significantly longer than typical periods observed for seismic seiches (30–90 s, [13,14,15,16,17]), but it is substantially shorter than the periods of the resonant spectral peaks found at the five other stations. It is, therefore, apparent that the 7 min oscillations were most likely to have been generated by seismic waves propagating through the solid earth.
To examine the open-ocean properties of the 2022 Michoacán tsunami waves seaward of the Mexican coast, we used the 1 min “Event-mode” data from DART 43412 DART (see [18,19] for details of the DART operations). The first (leading) wave, with an amplitude of 5.1 cm, was the maximum wave and arrived at this station at 18:42 UTC, i.e., 37 min after the main shock (Table 1).

4. Wavelet (f-t) and Spectral Analyses

To determine the temporal variations of the recorded 2022 tsunami waves in the frequency domain, we used a multiple-filter method, which is similar to wavelet analysis [10] and is based on narrow-band filters with a Gaussian window that isolates a specific centric frequency, ω n = 2 π f n . This method, which has been used effectively to examine the 2011 Tohoku and 2017 Chiapas tsunamis [6,7], as well as several other events [20,21], enabled us to determine changes in the tsunami waves as a function of frequency, f , and time, t , and to construct “f-t diagrams” (f-t plots) that display possible dispersion of the propagating waves. We selected 24 h level data segments and constructed corresponding f-t diagrams for the frequency band of 0.5–30 cph (Figure 2b).
The f-t plots for the four central stations look very similar. All display an abrupt and distinct tsunami arrival, as well as relatively long, well-defined, narrow and persistent frequency bands of strongly amplified energy associated with the tsunami wave oscillates. The slight differences are only in the dominant periods ~30–35 min at Manzanillo, ~20 min at Lazaro Cardenas, ~15 min at Zihuatanejo and 30 min at Acapulco, differences that are likely related to the fundamental resonant periods of the respective sites. At the two other sites, Puerto Vallarta and Huatulco, the f-t diagrams are different in that the tsunami arrival is less evident and the frequency bands of enhanced energy are less well defined. Nonetheless, even for these sites we can estimate the prevailing tsunami oscillation periods as 7 and 56 min for Puerto Vallarta and 9 and 4 min for Huatulco (Figure 2b).
To investigate the spectral properties of the tsunami waves during the 2022 Michoacán event, we separated the sea level records into two parts: (a) the pre-tsunami period (duration of 3.0 days), which was used to analyze the background oscillations, and (b) the period of 25.6 h following the tsunami wave arrival, which was used for the tsunami analysis. Our spectral analysis procedure was similar to that described by [10]. To improve delineation of the spectral estimates, we used a Kaiser–Bessel (KB) spectral window with half-window overlaps prior to the Fourier transform. The length of the window was chosen to be N = 512 min, yielding ν = 30 degrees of freedom for the background spectra, S bg ( ω ) , and ν = 10 for the tsunami spectra, S tsu ( ω ) . For both time periods, the spectral resolution was Δf = 0.117 cph. The results, shown in Figure 2, are in good agreement with those obtained from the f-t analysis: the spectra at the four central stations were characterized by sharp dominant spectral peaks (single or double) with periods of 29–35 min at Manzanillo, 15–18 min at Lazaro Cardenas, 17 min at Zihuatanejo and 30 min at Acapulco. All of these spectral peaks are the same as in the background spectra and all closely match the wave spectra at these stations during other tsunami events [5,6,7], indicating that the peaks are determined by the resonant topographic properties of the corresponding sites rather than by the source features. At the same time, there is a considerable difference, of about 1.5–2 order of magnitude, between the 2022 tsunami and background spectra in the energy level (Figure 4), demonstrating that during the event natural (eigen) oscillations at these sites were strongly amplified.
The spectral properties of the 2022 tsunami waves at the two distal stations, Puerto Vallarta and Huatulco, are markedly different from those at the central stations: there are no sharp peaks in the spectra at these stations and the tsunami spectra only marginally exceed the background spectra. Nevertheless, certain peaks of the topographic origin—56, 27 and 7 min at Puerto Vallarta and 9 and 4 min at Huatulco–are evident (Figure 4) and confirm our previous findings for these sites based on the f-t analysis.
The difference between the tsunami and background spectra shown in Table 1 provides a measure of the “pure tsunami energy”. The substantial difference from the “observed variance” provided in Column 8 of the table is because the latter includes the background variance and because the observed variance was estimated from the first 6 h of the most intensive oscillations, while the “pure energy (variance)” was estimated using the much longer one-day segment. However, qualitatively the results are the same: the maximum pure energy values are 298 cm2 at Manzanillo and 169 cm2 at Zihuatanejo, the minimum of 7 and 4 cm2 are at Puerto Vallarta and Huatulco, respectively.

5. Numerical Modelling

To numerically simulate the 2022 Michoacán tsunami, we used the “fast-track model” [11,22] that is based on a finite-difference formulation of the linear shallow-water equations and is similar to that of Imamura [23]. This model domain was confined to the northeast Pacific Ocean and creating using the GEBCO-2022 data set (https://www.gebco.net (accessed on 3 October 2022)), with a 30 arc-second interval grid. The entire grid size was 7200×6000 and the time step was chosen to be ~0.86 s to satisfy the Courant–Friedrichs–Lewy (CFL) criterion. In this simulation, we used the tsunami source model equations of Okada [24] and the finite-fault data provided by the USGS (https://earthquake.usgs.gov/earthquakes/eventpage/at00rigy8l/finite-fault (accessed on 3 October 2022)). Instead of applying the common hydrostatic approximation, we used Laplace’s equation and the non-hydrostatic correction technique [11,22,25] to convert the resulting sea floor displacement into an initial sea surface displacement.
A comparison between the modelled tsunami waveforms and the observed waveforms from DART 43412 and the six coastal stations is shown in Figure 5. The open-ocean DART record was used to validate our model. The good agreement between recorded and the simulated waveforms for this site (close matching of the first four waves) indicates that the model is of high quality. The model also works quite well for the coastal sites. As one would expect, the model is not capable of resolving the seismic seiches observed at Puerto Vallarta, but the tsunami signal is reproduced perfectly. Although there are significant differences between computed and measured amplitudes for Acapulco, the model accurately simulates the phase and period of the observed tsunami oscillations. It should be emphasized that the spatial resolution of the model (of about 900 m) is too coarse to resolve the exact coastal resonant features.

6. Discussion and Conclusions

One of the main purposes of this study was to compare the 2022 Michoacán tsunami with the 2017 Chiapas tsunami. To examine the spatial properties of these two events, we computed maps of the maximum tsunami amplitudes for the northeast Pacific Ocean. Numerical modelling of the 2017 tsunami was based on the same model parameters as for the 2022 tsunami and the USGS finite fault source model (https://earthquake.usgs.gov/earthquakes/eventpage/us2000ahv0/finite-fault (accessed on 3 October 2022)). The results of our simulations of the 2017 tsunami are in good agreement with those of Heidarzadeh et al. [26] and NOAA/PMEL (https://nctr.pmel.noaa.gov/mexico20170908/ (accessed on 3 October 2022)). The computed maps of maximum tsunami amplitudes for the 2017 and 2022 events are shown in Figure 6a,b, respectively. The 2017 Mw 8.2 earthquake was stronger than 2022 Mw 7.6 earthquake so that it is not unexpected that the maximum amplitudes for the 2017 tsunami were considerably higher than for the 2022 tsunami. However, what is noteworthy, is the markedly different character of the tsunami energy radiation patterns. The 2017 tsunami spread energy widely in a semicircular pattern emanating from the source (Figure 6a). In contrast, the main beam of offshore energy radiating outward from the 2022 event was directed like a “searchlight” oriented normally to the mainland coast (Figure 6b). In this aspect, the 2022 tsunami was similar to the 2012 Haida-Gwaii event that radiated tsunami energy in a narrow beam from the source area offshore of HaidaGwaii directly to the Hawaiian Islands [25]. The 2017/2022 difference explains the dichotomy in the spatial distributions of the recorded tsunami amplitudes at the coast. Specifically, the 2017 tsunami was recorded as far as 3000 km along the mainland coast, with trough-to-crest wave heights reaching >1 m within the first 1000 km coastline segment (Figure 3 and Figure 4 in [7]). In contrast, the 2022 tsunami was limited to corresponding segments of 1000 and 400 km, respectively (Figure 1).
We also used the observational data to compare the spectral ratios of these two events. Figure 7a shows the mean 2017 and 2022 tsunami/background spectral ratios, R ^ ( ω ) = S tsu ( ω ) / S bg ( ω ) , estimated by the averaging individual ratios over all coastal stations of the specific group. As shown by Rabinovich [27], values of R ^ ( ω ) are almost independent of the local topographic features and mostly determined by the external source forcing. Zaytsev et al. [6,7] used the corresponding ratios to reconstruct open-ocean tsunami spectra and obtained good agreement between reconstructed and actual spectra for the DART sites. The 2017 mean ratio (Figure 7a, left) has a relatively smooth dome shape with the main tsunami energy related to periods ranging from 15 to 75 min and the maximum R ^ ( ω ) value at a period of ~30 min; the 2022 ratio has a triangle shape with considerably shorter dominant periods of 10–50 min and the peak period of 18 min (Figure 7a, right).
The above estimates are based on coastal measurements of the two events. Figure 7b shows the open-ocean DART 43142 records and their f-t diagrams for the 2017 and 2022 tsunamis. It is clearly evident that the 2017 tsunami was characterized by much longer periods than the 2022 event, with the main energy “tails” at periods of 70 and 24 min, respectively.
Following [6,7], we integrated the true 2017 and 2022 tsunami spectra (not shown here for brevity) at DART 43412 over the entire tsunami frequency band, ω begin <   ω   <   ω end , and estimated the integral open-ocean tsunami energy index, I0. The resulting values of 0.14 cm2 for 2017 and 0.13 cm2 for 2022 are almost equal. Moreover, despite the fact that the 2017 Chiapas tsunami was generally the much stronger of the two events (see Figure 6b,c), the maximum tsunami amplitude recorded at 43412 was significantly smaller than for the 2022 event;3.2 and 5.1 cm, respectively (Figure 7b). This was likely caused by a larger distance from the source region, amounting to 1400 km for the 2017 event vs. only 465 km for the 2022 event. The difference in distance also accounts for the difference in tsunami travel times: ~1.5 h for 2017 and 37 min for 2022 (Figure 7b).
The main difference between the 2017 Chiapas and 2022 Michoacán tsunamis is in their frequency compositions. Following [5,6], we estimated the “tsunami colour” (or open-ocean frequency content). We separated the entire tsunami frequency band into six sub-bands and for each of these bands calculated the respective energy. The resulting coloured “pies” shown in Figure 7c indicate that the 2017 tsunami was mostly “reddish” (long-period), with 87% of energy at periods >35 min), while the 2022 tsunami was “bluish” (short-period), with 91% at periods <35 min. This difference appears to be related to the geometric dimensions and mean depth of the source areas [27,28]. For the source dimensions shown in Figure 7c and mean depth of 1760 and 1360 m for the 2017 and 2022 earthquakes, respectively, the typical periods are 35–50 min for 2017 and 8–20 min for 2022, in good agreement with the observations.
One of the unexpected results of our study was the discovery of seismic seiches at Puerto Vallarta. The seiches had a 7 min recorded period, began almost immediately after the main earthquake shock and lasted for about one hour (Figure 3). It appears that these seiches were enhanced by the resonant properties specific to the port area. The fundamental 7 min eigen period of the port was substantially shorter than similar periods at the other stations we examined and, consequently, closer to the typical periods of seismic body waves (30–90 s) propagating through the earth’s crust. It is for this reason that seismic seiches were observed at Puerto Vallarta but have not at the other stations.

Author Contributions

Conceptualization and data analysis, O.Z. and A.B.R.; methodology, A.B.R.; validation, R.E.T.; numerical modelling, E.T.; visualization, A.B.R. and O.Z.; writing—original draft preparation, O.Z. and A.B.R.; writing—review and editing, R.E.T. All authors have read and agreed to the published version of the manuscript.

Funding

This research was partially supported by the Mexican National Polytechnic Institute (IPN, project SIP 20220535), the IO RAS state assignment No. FMWE-2021-0004. Additional support for the first author was provided by SNI (Mexican National System of Investigators).

Data Availability Statement

The coastal tide-gauge data presented in this study are available on the UNESCO Intergovernmental Oceanographic Commission website, at www.ioc-sealevelmonitoring.org. The DART data are available on the website of the National Data Buoy Center (NDBC), NOAA, at www.ndbc.noaa.gov.

Acknowledgments

The authors acknowledge Emile Okal (Northwestern University, Evanston, IL, USA) for consulting with us on the seismological aspects of the 1985 and 2022 events. We gratefully acknowledge the Intergovernmental Oceanographic Commission (IOC), UNESCO, for providing sea level data from the coastal sea level gauges and NOAA National Centers for Environmental Information (Boulder, CO, USA) for providing the DART data.

Conflicts of Interest

The authors declare no conflict of interest.

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Figure 1. Map of coastal Mexico showing the maximum recorded tsunami wave heights at six coastal tide gauges (circles) for the 2022 Michoacán event; the size of a circle is proportional to the maximum recorded trough-to-crest wave height. The red star indicates the epicenter of the 2022 Michoacán earthquake (Mw 7.6), the light brown stars show the epicenters of the 1985 Michoacán (Mw 8.1) and 2017 Chiapas (Mw 8.2) earthquake, and the crimson square denotes location of DART 43412. White solid lines show the 2022 tsunami travel time (in hours and 10 min increments) from the source area.
Figure 1. Map of coastal Mexico showing the maximum recorded tsunami wave heights at six coastal tide gauges (circles) for the 2022 Michoacán event; the size of a circle is proportional to the maximum recorded trough-to-crest wave height. The red star indicates the epicenter of the 2022 Michoacán earthquake (Mw 7.6), the light brown stars show the epicenters of the 1985 Michoacán (Mw 8.1) and 2017 Chiapas (Mw 8.2) earthquake, and the crimson square denotes location of DART 43412. White solid lines show the 2022 tsunami travel time (in hours and 10 min increments) from the source area.
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Figure 2. (a) The 2022 tsunami recorded at six Mexican UNAM tide gauges. The solid vertical red line labelled “E” denotes the time of the earthquake. The label “SS” indicates seismic seiches induced at station Puerto Vallarta immediately after the earthquake. (b) f-t plots for six the 2022 tsunami records shown in Figure 2a for six coastal tide gauges located close to the source area. The dashed vertical white lines denote the time of the tsunami arrivals.
Figure 2. (a) The 2022 tsunami recorded at six Mexican UNAM tide gauges. The solid vertical red line labelled “E” denotes the time of the earthquake. The label “SS” indicates seismic seiches induced at station Puerto Vallarta immediately after the earthquake. (b) f-t plots for six the 2022 tsunami records shown in Figure 2a for six coastal tide gauges located close to the source area. The dashed vertical white lines denote the time of the tsunami arrivals.
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Figure 3. The record and f-t plot of seismic seiches in Puerto Vallarta.
Figure 3. The record and f-t plot of seismic seiches in Puerto Vallarta.
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Figure 4. Spectra of background (pre-tsunami) and 2022 Michoacán tsunami sea level oscillations recorded at six coastal tide gauges shown in Figure 1. The 95% confidence level applies to the tsunami spectra, the 99% confidence level to the background spectra. The shaded areas denote the tsunami energy. The numbers in blue indicate the total spectral energy of tsunami waves (integrated over the shaded areas).
Figure 4. Spectra of background (pre-tsunami) and 2022 Michoacán tsunami sea level oscillations recorded at six coastal tide gauges shown in Figure 1. The 95% confidence level applies to the tsunami spectra, the 99% confidence level to the background spectra. The shaded areas denote the tsunami energy. The numbers in blue indicate the total spectral energy of tsunami waves (integrated over the shaded areas).
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Figure 5. Computed (red) and observed (black) 2022 tsunami waveforms for DART 43412 and six coastal tide gauges. The solid vertical red line labelled “E” denotes the time of the earthquake, “Rw” indicates the Rayleigh waves recorded at DART 43412 and “SS” seismic seiches recorded at Puerto Vallarta.
Figure 5. Computed (red) and observed (black) 2022 tsunami waveforms for DART 43412 and six coastal tide gauges. The solid vertical red line labelled “E” denotes the time of the earthquake, “Rw” indicates the Rayleigh waves recorded at DART 43412 and “SS” seismic seiches recorded at Puerto Vallarta.
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Figure 6. Numerically simulated maximum tsunami amplitudes for the 2017 Chiapas and 2022 Michoacán earthquakes are shown in (a) and (b), respectively.
Figure 6. Numerically simulated maximum tsunami amplitudes for the 2017 Chiapas and 2022 Michoacán earthquakes are shown in (a) and (b), respectively.
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Figure 7. Comparison of spectral characteristics for the 2017 Chiapas (Mw 8.2) and 2022 Michoacán (Mw 8.2) tsunamis on the Mexican coast. (a) Mean (averaged over all coastal stations in the source area) 2017 and 2022 tsunami/background spectral ratios. (b) DART 43412 records of the 2017 and 2022 tsunamis; red line labelled “E” denotes the time of the earthquake, “Rw” indicates the Rayleigh waves. (c) The initial 2017 and 2022 tsunami sources, with specified spatial source scales, and integral open-ocean tsunami energy indices, I0, estimated for DART 43412. The areas of the circles are proportional to log(I0); the different coloured segments within a given circle denote different period partitions, as indicated in the legend; the numbers in the circle centers show the I0 values (in cm2) and the numbers in the sectors give the relative partitions (in %).
Figure 7. Comparison of spectral characteristics for the 2017 Chiapas (Mw 8.2) and 2022 Michoacán (Mw 8.2) tsunamis on the Mexican coast. (a) Mean (averaged over all coastal stations in the source area) 2017 and 2022 tsunami/background spectral ratios. (b) DART 43412 records of the 2017 and 2022 tsunamis; red line labelled “E” denotes the time of the earthquake, “Rw” indicates the Rayleigh waves. (c) The initial 2017 and 2022 tsunami sources, with specified spatial source scales, and integral open-ocean tsunami energy indices, I0, estimated for DART 43412. The areas of the circles are proportional to log(I0); the different coloured segments within a given circle denote different period partitions, as indicated in the legend; the numbers in the circle centers show the I0 values (in cm2) and the numbers in the sectors give the relative partitions (in %).
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Table 1. Parameters of the 2022 Michoacán (Mexican) tsunami of 19 September 2022 recorded by UNAM tide gauges on the Mexican coast by near-field open-ocean DART 43413 (Main shock, Mw 7.6, at 18:05 UTC).
Table 1. Parameters of the 2022 Michoacán (Mexican) tsunami of 19 September 2022 recorded by UNAM tide gauges on the Mexican coast by near-field open-ocean DART 43413 (Main shock, Mw 7.6, at 18:05 UTC).
StationFirst WaveMaximum WaveObserved Tsunami Variance (cm2)Spectral Tsunami Energy (cm2)
Arrival Time (UTC)Travel Time (hh:mm)Amplitude (cm) &SignAmplitude (cm)Arrival Time (UTC)Wave Height (cm)
Puerto Vallarta19:231:18+5.07.020:3913.024.07.0
Manzanillo18:230:18+36.098.019:10172.0966.0297.9
Lazaro Cardenas18:320:27+11.032.022:0867.0145.160.5
Zihuatanejo18:380:33+27.049.021:28102.0435.2169.7
Acapulco19:040:59+16.031.020:3268.0156.276.2
Huatulco19:421:37+4.09.021:5717.019.57.0
DART 4341218:420:37+5.15.118:487.40.470.13
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Zaytsev, O.; Tsukanova, E.; Rabinovich, A.B.; Thomson, R.E. The Michoacán Tsunami of 19 September 2022 on the Coast of Mexico: Observations, Spectral Properties and Modelling. Water 2023, 15, 164. https://doi.org/10.3390/w15010164

AMA Style

Zaytsev O, Tsukanova E, Rabinovich AB, Thomson RE. The Michoacán Tsunami of 19 September 2022 on the Coast of Mexico: Observations, Spectral Properties and Modelling. Water. 2023; 15(1):164. https://doi.org/10.3390/w15010164

Chicago/Turabian Style

Zaytsev, Oleg, Elizaveta Tsukanova, Alexander B. Rabinovich, and Richard E. Thomson. 2023. "The Michoacán Tsunami of 19 September 2022 on the Coast of Mexico: Observations, Spectral Properties and Modelling" Water 15, no. 1: 164. https://doi.org/10.3390/w15010164

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